Thyroid Disease
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Questions and Answers

What percentage of ultrasound-detected thyroid nodules are typically malignant?

  • 10% (correct)
  • 20%
  • 15%
  • 5%

    • What is the primary method for imaging evaluation of thyroid masses?

  • MRI
  • CT Scan
  • Ultrasound (correct)
  • X-ray

    • Which of the following factors increases the risk of thyroid nodules?

  • Family history of diabetes
  • Iodine deficiency (correct)
  • Age under 30
  • High blood pressure

    • Which ultrasound pattern indicates high suspicion for thyroid malignancy?

    <p>Hypoechoic solid nodule with irregular borders</p> Signup and view all the answers

    How can toxic adenomas lead to thyrotoxicosis?

    <p>Through autonomous endocrine activity</p> Signup and view all the answers

    What is the primary hormone secreted by the thyroid gland?

    <p>T4 (Thyroxine)</p> Signup and view all the answers

    Which metabolic effect is associated with low levels of T3 and T4?

    <p>Glycogen synthesis</p> Signup and view all the answers

    What is the primary physiological role of T3 in the body?

    <p>Increase basal metabolic rate</p> Signup and view all the answers

    Which hormone is produced by the anterior pituitary gland and stimulates the thyroid?

    <p>TSH</p> Signup and view all the answers

    What percentage of the thyroid gland's output is T3?

    <p>20%</p> Signup and view all the answers

    Which of the following best describes the serum half-life of T3 compared to T4?

    <p>T3 has a shorter half-life than T4</p> Signup and view all the answers

    Which metabolic mechanism is NOT a function of thyroid hormones?

    <p>Decrease protein synthesis</p> Signup and view all the answers

    What is the role of calcitonin in the body?

    <p>Regulate amount of calcium in the body</p> Signup and view all the answers

    What is the recommended frequency for checking TSH in pregnant patients diagnosed with hypothyroidism?

    <p>Every 6 weeks</p> Signup and view all the answers

    Which of the following conditions should be checked for if a patient continues to experience hypothyroid symptoms despite normal thyroid levels?

    <p>Adrenal insufficiency</p> Signup and view all the answers

    What is the most common cause of secondary hypothyroidism?

    <p>Pituitary adenoma</p> Signup and view all the answers

    Which imaging modality is indicated for diagnosing pituitary pathology in cases of secondary hypothyroidism?

    <p>MRI</p> Signup and view all the answers

    What are the expected laboratory findings for TSH and Free T4 in secondary hypothyroidism?

    <p>Low TSH and low Free T4</p> Signup and view all the answers

    What type of symptoms are typically associated with secondary hypothyroidism?

    <p>Symptoms similar to primary hypothyroidism</p> Signup and view all the answers

    Which thyroid hormone replacement therapy is used for treating secondary hypothyroidism?

    <p>Thyroxine</p> Signup and view all the answers

    What additional symptoms might indicate other pituitary hormone abnormalities in secondary hypothyroidism?

    <p>Vision changes and headaches</p> Signup and view all the answers

    Which of the following symptoms is commonly associated with Hashimoto’s thyroiditis?

    <p>Goiter</p> Signup and view all the answers

    What is the most common cause of hypothyroidism in North America?

    <p>Hashimoto’s thyroiditis</p> Signup and view all the answers

    Which diagnostic test is definitive for diagnosing primary hypothyroidism?

    <p>Elevated TSH</p> Signup and view all the answers

    Which medication is commonly used for treating primary hypothyroidism?

    <p>Levothyroxine</p> Signup and view all the answers

    Which condition may present with high mortality and an altered level of consciousness during severe hypothyroidism?

    <p>Myxedema coma</p> Signup and view all the answers

    What is the recommended starting dose of Levothyroxine for hypothyroidism in adults?

    <p>50-200 mcg daily</p> Signup and view all the answers

    Which autoantibodies are commonly associated with Hashimoto’s thyroiditis?

    <p>Both A and B</p> Signup and view all the answers

    What additional monitoring should be performed in patients with hypothyroidism to check for associated metabolic issues?

    <p>Serum cholesterol and triglyceride levels</p> Signup and view all the answers

    Which phenomenon may occur during the early destructive phase of Hashimoto’s thyroiditis?

    <p>Transient hyperthyroidism</p> Signup and view all the answers

    What is the effect of smoking on Hashimoto's thyroiditis?

    <p>Increases the risk</p> Signup and view all the answers

    What is the most accurate characterization of a 'cold' nodule on a thyroid scan?

    <p>85% benign with a higher risk of malignancy.</p> Signup and view all the answers

    Which of the following conditions require an FNA for solitary thyroid nodules?

    <p>Mixed cystic-solid nodules greater than 1.5 cm with suspicious features.</p> Signup and view all the answers

    What is the first-line treatment for a toxic thyroid adenoma?

    <p>Radioactive iodine therapy.</p> Signup and view all the answers

    What percentage of cold nodules are typically benign?

    <p>85%</p> Signup and view all the answers

    Which of the following increases a patient's risk of thyroid cancer?

    <p>A history of regional irradiation.</p> Signup and view all the answers

    Which parameter is important for evaluating nodules when using FNA biopsy?

    <p>Ensuring it is done under ultrasound guidance.</p> Signup and view all the answers

    What is the risk of malignancy in warm nodules?

    <p>10%</p> Signup and view all the answers

    What is a possible symptom of a toxic thyroid adenoma?

    <p>Dysphagia.</p> Signup and view all the answers

    In which circumstance is FNA of nonpalpable (incidental) thyroid nodules indicated?

    <p>If the nodule is larger than 1.5 cm.</p> Signup and view all the answers

    What is a common recommendation for managing thyroid nodules associated with elevated TSH?

    <p>Levothyroxine treatment to suppress TSH levels.</p> Signup and view all the answers

    What is the primary role of thyroid hormones in the body?

    <p>Increasing the basal metabolic rate</p> Signup and view all the answers

    Which statement about T3 and T4 is correct?

    <p>T4 is less physiologically active than T3.</p> Signup and view all the answers

    What effect do low levels of thyroid hormones have on protein metabolism?

    <p>Increase protein synthesis</p> Signup and view all the answers

    What is the role of calcitonin produced by the thyroid gland?

    <p>It regulates calcium levels in the body.</p> Signup and view all the answers

    How does the production of T3 occur predominantly in the body?

    <p>Conversion of T4 into T3 by de-iodination</p> Signup and view all the answers

    What are the metabolic effects of excessive levels of thyroid hormones?

    <p>Increased protein degradation</p> Signup and view all the answers

    Which function is not directly associated with thyroid hormones?

    <p>Regulate immune system activity</p> Signup and view all the answers

    What is the main function of TSH in the hormonal pathway of the thyroid gland?

    <p>Stimulate thyroid hormone production</p> Signup and view all the answers

    What is the most prevalent factor contributing to Hashimoto’s thyroiditis?

    <p>A genetic deficiency in antigen-specific suppressor T-cells</p> Signup and view all the answers

    Which symptom is commonly observed in patients with severe hypothyroidism?

    <p>Dry skin and swelling</p> Signup and view all the answers

    What is a significant change in hormonal levels indicative of primary hypothyroidism?

    <p>Increased TSH and decreased Free T4</p> Signup and view all the answers

    What treatment adjustment should be considered for elderly and cardiac patients when initiating Levothyroxine?

    <p>Start low and increase slowly</p> Signup and view all the answers

    Which of the following is a major characteristic of myxedema coma?

    <p>Altered level of consciousness</p> Signup and view all the answers

    What is the potential benefit of combining T3 and T4 therapy for hypothyroidism?

    <p>To enhance symptom management for those who do not process T4 efficiently</p> Signup and view all the answers

    In Hashimoto’s thyroiditis, what laboratory findings are typically present?

    <p>Elevated TSH, low thyroid hormone, and presence of anti-thyroid peroxidase antibodies</p> Signup and view all the answers

    Which condition is often associated with Hashimoto’s thyroiditis?

    <p>Celiac disease</p> Signup and view all the answers

    What is a common characteristic of goiter associated with Hashimoto’s thyroiditis?

    <p>Irregular and firm consistency</p> Signup and view all the answers

    What dietary factor has been linked to increased prevalence of Hashimoto’s thyroiditis?

    <p>High dietary iodine intake</p> Signup and view all the answers

    Which characteristic is true for a cold thyroid nodule?

    <p>They do not take up radioactive iodine and appear white on scans.</p> Signup and view all the answers

    What is the typical malignancy risk percentage associated with warm thyroid nodules?

    <p>10% malignant</p> Signup and view all the answers

    Which type of biopsy is indicated for solitary thyroid nodules larger than 5 mm?

    <p>Fine needle aspiration (FNA) biopsy</p> Signup and view all the answers

    What is the primary treatment option for a toxic thyroid adenoma?

    <p>Radioactive iodine therapy</p> Signup and view all the answers

    Which scenario includes an indication for extra monitoring or re-biopsy of thyroid nodules?

    <p>Nodules with associated elevated TSH levels</p> Signup and view all the answers

    In the context of thyroid nodules, what is a potential consequence of levothyroxine treatment in postmenopausal women?

    <p>Loss of bone density</p> Signup and view all the answers

    What is the main feature of nonpalpable thyroid nodules found during imaging for other reasons?

    <p>Only monitored if larger than 1.5 cm</p> Signup and view all the answers

    What finding is most indicative of a malignant thyroid nodule?

    <p>Microcalcifications and solid appearance</p> Signup and view all the answers

    Which statement about the prognosis of thyroid nodules is accurate?

    <p>Incidental nodules rarely turn out to be malignant.</p> Signup and view all the answers

    Which demographic factor is associated with increased incidence of thyroid cancer?

    <p>Older age and female gender</p> Signup and view all the answers

    What is the most common histological type of thyroid cancer?

    <p>Papillary carcinoma</p> Signup and view all the answers

    Which of the following treatments is commonly included for patients with papillary or follicular thyroid cancer?

    <p>Radioactive iodine ablation</p> Signup and view all the answers

    What is a characteristic feature of medullary thyroid carcinoma?

    <p>Linked to RET mutations</p> Signup and view all the answers

    What represents a significant prognostic factor for follicular carcinoma?

    <p>Patient age at diagnosis</p> Signup and view all the answers

    Which thyroiditis subtype is typically autoimmune and may present as painless inflammation?

    <p>Chronic lymphocytic thyroiditis</p> Signup and view all the answers

    What is the expected clinical course of painless lymphocytic thyroiditis?

    <p>Transient hyperthyroidism followed by hypothyroidism</p> Signup and view all the answers

    What is the typical survival rate associated with well-differentiated thyroid cancers like papillary thyroid carcinoma?

    <p>90% at 10 years</p> Signup and view all the answers

    What is a common marker used to monitor residual or recurrent medullary thyroid carcinoma?

    <p>Calcitonin</p> Signup and view all the answers

    What is a common cause of acute infectious thyroiditis?

    <p>Bacterial infection</p> Signup and view all the answers

    What underlying condition should be excluded in all patients with medullary thyroid carcinoma prior to surgical intervention?

    <p>Pheochromocytoma</p> Signup and view all the answers

    Which feature is considered unique to Graves' disease?

    <p>Orbitopathy</p> Signup and view all the answers

    What is the primary treatment for symptomatic relief of tachycardia in hyperthyroidism?

    <p>Propranolol</p> Signup and view all the answers

    Which of the following conditions typically leads to transient inflammation of the thyroid?

    <p>Subacute Thyroiditis</p> Signup and view all the answers

    What laboratory finding is typically seen in Graves' disease?

    <p>Increased T3</p> Signup and view all the answers

    Which clinical presentation is associated with toxic multinodular goiter?

    <p>Atrial fibrillation</p> Signup and view all the answers

    What is a common disadvantage of thionamides as a treatment for hyperthyroidism?

    <p>Risk of agranulocytosis</p> Signup and view all the answers

    Which thyroid condition is known to cause soft-tissue swelling and clubbing of fingers?

    <p>Graves' disease</p> Signup and view all the answers

    Which of the following is NOT a common sign of hyperthyroidism?

    <p>Cold intolerance</p> Signup and view all the answers

    What common diagnostic tool is used to evaluate thyroid nodules?

    <p>Ultrasonography</p> Signup and view all the answers

    What should be monitored to assess potential autoimmune thyroid disease risk?

    <p>TPO antibodies</p> Signup and view all the answers

    What is the most common cause of hyperthyroidism in older patients?

    <p>Toxic multinodular goiter</p> Signup and view all the answers

    Which of the following treatments ablates thyroid tissue in hyperthyroidism?

    <p>Radioactive iodine</p> Signup and view all the answers

    Which statement is true regarding the incidence of thyroid nodules?

    <p>Three times more common in females than males</p> Signup and view all the answers

    What is the main characteristic of a benign thyroid adenoma?

    <p>Non-cancerous neoplasm</p> Signup and view all the answers

    What appearance do cold nodules have on a thyroid scan?

    <p>White</p> Signup and view all the answers

    What percentage of hot nodules are typically malignant?

    <p>5%</p> Signup and view all the answers

    Which clinical finding is commonly associated with toxic thyroid adenoma?

    <p>Choking sensation</p> Signup and view all the answers

    In which situation is fine needle aspiration (FNA) indicated for solitary thyroid nodules?

    <p>Solid nodules ≥ 1 cm with microcalcifications</p> Signup and view all the answers

    What is the typical management approach for nodules associated with elevated TSH?

    <p>Levothyroxine treatment</p> Signup and view all the answers

    What is the risk of malignancy for warm nodules?

    <p>10%</p> Signup and view all the answers

    Which diagnostic method is preferred for evaluating thyroid nodules?

    <p>Ultrasound guided FNA</p> Signup and view all the answers

    What are the potential adverse effects of levothyroxine treatment in postmenopausal women?

    <p>Loss of bone density</p> Signup and view all the answers

    Which of the following best describes the character of multinodular goiters over time?

    <p>Persist or grow slowly</p> Signup and view all the answers

    What factor significantly increases the incidence of thyroid cancer?

    <p>Age</p> Signup and view all the answers

    Which of the following best describes the relationship between T3 and T4 production in the thyroid gland?

    <p>T4 is the primary output of the thyroid gland, accounting for about 80% of total production.</p> Signup and view all the answers

    What effect do low levels of thyroid hormones have on carbohydrate metabolism?

    <p>They enhance glycogen synthesis and glucose utilization.</p> Signup and view all the answers

    How does thyroid hormone affect lipid metabolism?

    <p>It increases both lipolysis and fatty acid oxidation.</p> Signup and view all the answers

    What is the physiological significance of T3's shorter serum half-life compared to T4?

    <p>T3 acts more rapidly than T4 due to its quicker metabolic clearance.</p> Signup and view all the answers

    Which hormone is primarily responsible for regulating calcium levels in the body?

    <p>Calcitonin</p> Signup and view all the answers

    What role does thyroid hormone play in regulating long bone growth?

    <p>Thyroid hormones regulate bone growth primarily through indirect action with growth hormone.</p> Signup and view all the answers

    What effect does excessive levels of thyroid hormones have on protein metabolism?

    <p>They stimulate protein degradation, leading to negative nitrogen balance.</p> Signup and view all the answers

    In the context of thyroid function tests (TFTs), which parameter is specifically measured to assess thyroid stimulating hormone levels?

    <p>TSH</p> Signup and view all the answers

    Which symptom is not typically associated with severe hypothyroidism known as myxedema?

    <p>Increased heart rate</p> Signup and view all the answers

    What is the primary reason for the increase in TSH levels seen in primary hypothyroidism?

    <p>Decreased feedback inhibition to the pituitary</p> Signup and view all the answers

    Which autoantibody is typically elevated in patients diagnosed with Hashimoto’s thyroiditis?

    <p>Anti-thyroid peroxidase antibody</p> Signup and view all the answers

    During the early destructive phase of Hashimoto's thyroiditis, what phenomenon might occur?

    <p>Transient hyperthyroidism</p> Signup and view all the answers

    What is the appropriate starting dose of Levothyroxine for treating adults with hypothyroidism?

    <p>1.6 mcg/kg PO qd</p> Signup and view all the answers

    How does smoking impact the risk associated with Hashimoto's thyroiditis?

    <p>Increases the risk</p> Signup and view all the answers

    Which of the following is a common laboratory finding associated with hypothyroidism?

    <p>Elevated TSH levels</p> Signup and view all the answers

    What is the significance of monitoring TSH levels after initiating treatment for hypothyroidism?

    <p>To evaluate the efficacy of the therapy</p> Signup and view all the answers

    Which of the following statements is true regarding the treatment of hypothyroidism?

    <p>T3 supplementation can be beneficial for some patients</p> Signup and view all the answers

    Which medical condition is commonly associated with Hashimoto’s thyroiditis?

    <p>Diabetes mellitus type 1</p> Signup and view all the answers

    What is the primary role of thyroxine-binding globulin (TBG) in thyroid hormone regulation?

    <p>To bind and transport T3 and T4 in the bloodstream</p> Signup and view all the answers

    Which condition is a hallmark of primary hypothyroidism?

    <p>Inability of the thyroid gland to produce adequate T3 and T4</p> Signup and view all the answers

    What significant risk factor is associated with congenital hypothyroidism?

    <p>Incidence of 1 in 4000 newborns</p> Signup and view all the answers

    What is the typical range for free T4 (fT4) in adult patients?

    <p>0.8 – 1.8 ng/dL</p> Signup and view all the answers

    In cases of high resin T3 uptake, what does this indicate about serum thyroid-binding proteins (TBP)?

    <p>Serum TBP levels are low</p> Signup and view all the answers

    What is the most common etiology of primary hypothyroidism?

    <p>Autoimmune Thyroiditis (Hashimoto disease)</p> Signup and view all the answers

    At what age range is the incidence of Autoimmune Thyroiditis (Hashimoto disease) highest?

    <p>30-50 years</p> Signup and view all the answers

    What is the role of the free thyroxine index (FTI) in thyroid function tests?

    <p>To adjust Total T4 for abnormal TBG levels</p> Signup and view all the answers

    What does a normal Total T3 range of 75-220 ng/dL imply for a patient?

    <p>Normal thyroid function</p> Signup and view all the answers

    When should thyroid function screening be performed for men?

    <p>Every 4-5 years</p> Signup and view all the answers

    What is a primary characteristic of Graves' disease related to the thyroid gland?

    <p>Presence of TSH receptor antibodies</p> Signup and view all the answers

    Which symptom is associated uniquely with Graves' disease?

    <p>Pretibial myxedema</p> Signup and view all the answers

    What diagnostic finding is most consistent with hyperthyroidism?

    <p>Elevated Free T3 and T4</p> Signup and view all the answers

    What is the major side effect risk associated with thionamides used in hyperthyroidism treatment?

    <p>Agranulocytosis</p> Signup and view all the answers

    Which imaging technique is most effective for evaluating tracheal compression due to a goiter?

    <p>CT or MRI</p> Signup and view all the answers

    What treatment is considered first-line for toxic multinodular goiter?

    <p>Radioactive iodine</p> Signup and view all the answers

    Which clinical finding is NOT typical in patients with diffuse nontoxic goiter?

    <p>Presence of palpable nodules</p> Signup and view all the answers

    What is a key feature that distinguishes toxic multinodular goiter from nontoxic multinodular goiter?

    <p>Presence of functional autonomy</p> Signup and view all the answers

    Which factor is NOT commonly linked to the development of a goiter?

    <p>High levels of dietary iodine</p> Signup and view all the answers

    In the context of thyroid neoplasia, which statement best describes a thyroid nodule?

    <p>May be benign or malignant</p> Signup and view all the answers

    Which condition is often associated with increased TSH receptor antibodies?

    <p>Graves' disease</p> Signup and view all the answers

    What is one common symptom of toxic multinodular goiter in elderly patients?

    <p>Atrial fibrillation</p> Signup and view all the answers

    What is the primary medical management for a patient with new-onset severe hyperthyroid symptoms?

    <p>Antithyroid medication therapy</p> Signup and view all the answers

    What is the primary underlying issue in secondary hypothyroidism?

    <p>Decreased TSH production</p> Signup and view all the answers

    Which of the following diagnostic evaluations is most indicative of a pituitary adenoma in secondary hypothyroidism?

    <p>Coronal T1-weighted postcontrast MRI</p> Signup and view all the answers

    What is a possible symptom of secondary hypothyroidism related to pituitary dysfunction?

    <p>Vision changes</p> Signup and view all the answers

    What is the primary treatment approach for a patient diagnosed with secondary hypothyroidism?

    <p>Thyroxine replacement with endocrine consult</p> Signup and view all the answers

    Which condition is most commonly associated with secondary hypothyroidism due to pituitary dysfunction?

    <p>Pituitary adenoma</p> Signup and view all the answers

    When monitoring secondary hypothyroidism, how often should Free T4 levels be assessed after adjusting thyroxine doses?

    <p>Every 4-8 weeks</p> Signup and view all the answers

    If a patient exhibits symptoms of hypothyroidism but has normal thyroid levels, which condition should be investigated as a possible cause?

    <p>Adrenal insufficiency</p> Signup and view all the answers

    What would you expect to find in laboratory evaluations of a patient with secondary hypothyroidism?

    <p>Low TSH and Low Free T4</p> Signup and view all the answers

    Which imaging technique is less commonly used due to cost and the accuracy of ultrasound for evaluating thyroid masses?

    <p>Magnetic Resonance Imaging (MRI)</p> Signup and view all the answers

    In regions where iodine deficiency is prevalent, what kind of thyroid enlargement is common?

    <p>Diffuse goiter</p> Signup and view all the answers

    What percentage of thyroid nodules that are palpable are often benign adenomas or colloid nodules?

    <p>90%</p> Signup and view all the answers

    What is a potential consequence of a toxic adenoma functioning autonomously?

    <p>Thyrotoxicosis</p> Signup and view all the answers

    What characteristic ultrasound pattern is associated with a very low suspicion for thyroid malignancy?

    <p>Spongiform nodule with microcystic areas over 50% nodule volume</p> Signup and view all the answers

    What is the primary role of Thyroid Stimulating Hormone (TSH) in thyroid function?

    <p>Stimulates the thyroid tissue to increase thyroxine output</p> Signup and view all the answers

    Which condition is most commonly associated with primary hypothyroidism?

    <p>Autoimmune Thyroiditis (Hashimoto disease)</p> Signup and view all the answers

    What does a high resin T3 (or T4) uptake indicate?

    <p>Low levels of serum thyroid-binding proteins</p> Signup and view all the answers

    What is the normal range for Free T4 (fT4)?

    <p>0.8 – 1.8 ng/dL</p> Signup and view all the answers

    When is it generally recommended to screen thyroid function in men?

    <p>Every 4-5 years</p> Signup and view all the answers

    Which age group shows the highest prevalence of subclinical hypothyroidism?

    <p>Individuals over 65 years</p> Signup and view all the answers

    What factor is a leading cause of hypothyroidism in developing countries?

    <p>Iodine deficiency</p> Signup and view all the answers

    Which laboratory assay provides the most accurate measurement of thyroid status?

    <p>Ultra-sensitive TSH and Free T4 assays</p> Signup and view all the answers

    In hypothyroidism, which form accounts for 95% of cases?

    <p>Primary hypothyroidism</p> Signup and view all the answers

    Which of the following is NOT a characteristic of myxedema?

    <p>Increased basal metabolic rate</p> Signup and view all the answers

    What is the primary treatment for primary hypothyroidism?

    <p>Levothyroxine (Synthroid)</p> Signup and view all the answers

    Which autoantibody is commonly associated with Hashimoto’s thyroiditis?

    <p>Anti-thyroid peroxidase antibody</p> Signup and view all the answers

    Which of the following conditions is associated with increased risks when smoking?

    <p>Hashimoto’s thyroiditis</p> Signup and view all the answers

    What common symptom may result from severe hypothyroidism in adults?

    <p>Severe fatigue</p> Signup and view all the answers

    What is the typical dose range for Levothyroxine in adults starting treatment for hypothyroidism?

    <p>50-200 mcg PO qd</p> Signup and view all the answers

    What is the hallmark laboratory finding indicating primary hypothyroidism?

    <p>Elevated TSH</p> Signup and view all the answers

    Which additional condition is commonly seen along with Hashimoto’s thyroiditis?

    <p>Celiac disease</p> Signup and view all the answers

    In which phase might Hashimoto’s thyroiditis cause early transient hyperthyroidism?

    <p>Destructive phase</p> Signup and view all the answers

    What is the relationship between serum cholesterol levels and hypothyroidism?

    <p>Many hypothyroid patients may have high serum cholesterol and/or triglyceride levels</p> Signup and view all the answers

    What is the primary characteristic of a cold thyroid nodule?

    <p>It does not take up radioactive iodine.</p> Signup and view all the answers

    Which statement best describes the prognosis of solitary thyroid nodules?

    <p>Only a small percentage of solitary nodules lead to significant complications.</p> Signup and view all the answers

    Which type of nodule is characterized by intermediate characteristics and has a higher likelihood of being malignant than a cold nodule?

    <p>Warm nodule</p> Signup and view all the answers

    What is a crucial indication for performing a fine needle aspiration (FNA) biopsy on a thyroid nodule?

    <p>Solitary nodules of any size with suspicious appearance on ultrasound.</p> Signup and view all the answers

    Which treatment method is indicated for patients with a toxic thyroid adenoma?

    <p>Radioactive iodine as the treatment of choice.</p> Signup and view all the answers

    Which factor increases the risk of thyroid cancer in general?

    <p>Past history of regional irradiation.</p> Signup and view all the answers

    What is a potential symptom of a hyperfunctioning solitary nodule, also known as toxic thyroid adenoma?

    <p>Dysphagia or choking sensation.</p> Signup and view all the answers

    What is the anticipated outcome for incidental thyroid nodules detected through imaging modalities like MRI or CT?

    <p>They require FNA only if larger than 1.5 cm.</p> Signup and view all the answers

    Which of the following characteristics is NOT typically associated with cold nodules on a thyroid scan?

    <p>Increased uptake of radioactive iodine.</p> Signup and view all the answers

    Which imaging method is rarely used for evaluating thyroid masses due to its cost and lower accuracy compared to other methods?

    <p>MRI</p> Signup and view all the answers

    What is the primary function of fine needle aspiration (FNA) in the context of thyroid mass evaluation?

    <p>To obtain tissue for analysis</p> Signup and view all the answers

    Which of the following conditions is NOT typically associated with the presence of thyroid nodules?

    <p>Hyperparathyroidism</p> Signup and view all the answers

    What characteristic pattern on ultrasound suggests a very low suspicion for thyroid malignancy?

    <p>Spongiform nodule with microcystic areas</p> Signup and view all the answers

    Which factor has been identified as increasing the risk of developing thyroid nodules?

    <p>History of head/neck irradiation</p> Signup and view all the answers

    What is the most common cause of secondary hypothyroidism?

    <p>Pituitary adenoma</p> Signup and view all the answers

    Which of the following treatments is necessary for managing secondary hypothyroidism?

    <p>Thyroxine replacement therapy</p> Signup and view all the answers

    Which diagnostic evaluation would not be commonly used for assessing secondary hypothyroidism?

    <p>Complete blood count (CBC)</p> Signup and view all the answers

    What hormonal level is typically expected in a patient with secondary hypothyroidism?

    <p>Low TSH, low Free T4</p> Signup and view all the answers

    Which symptom is least likely to be associated with secondary hypothyroidism?

    <p>Weight loss</p> Signup and view all the answers

    Which of the following conditions should be investigated if hypothyroid symptoms persist despite normal thyroid levels?

    <p>Depression</p> Signup and view all the answers

    What is the recommended follow-up frequency for TSH measurement in patients with normalized thyroid levels?

    <p>Every 6-12 months</p> Signup and view all the answers

    What imaging modality is most appropriate for diagnosing a pituitary adenoma in secondary hypothyroidism?

    <p>Coronal T1-weighted MRI</p> Signup and view all the answers

    What is the likelihood of malignancy in cold nodules?

    <p>15%</p> Signup and view all the answers

    Which of the following is a necessary condition for Fine Needle Aspiration (FNA) of solitary thyroid nodules?

    <p>Nodules ≥ 1 cm diameter that are solid or have microcalcifications</p> Signup and view all the answers

    What is the expected outcome for the majority of thyroid nodules over time?

    <p>Remain benign</p> Signup and view all the answers

    What treatment is typically preferred for a toxic thyroid adenoma in non-pregnant patients?

    <p>Radioactive Iodine</p> Signup and view all the answers

    In what circumstance would an incidental thyroid nodule require an FNA?

    <p>If it has a history of head/neck irradiation</p> Signup and view all the answers

    Which symptom is commonly associated with a toxic thyroid adenoma?

    <p>Choking sensation</p> Signup and view all the answers

    What complication can arise from long-term suppression of TSH in postmenopausal women?

    <p>Loss of bone density</p> Signup and view all the answers

    What percentage of warm nodules are typically malignant?

    <p>10%</p> Signup and view all the answers

    How is a cold nodule typically characterized on a thyroid scan?

    <p>Does not take up radioactive iodine</p> Signup and view all the answers

    What is the most common type of thyroid cancer associated with a high 10-year survival rate?

    <p>Papillary carcinoma</p> Signup and view all the answers

    Which type of thyroid cancer is most often linked to hereditary syndromes?

    <p>Medullary carcinoma</p> Signup and view all the answers

    Which characteristic is NOT typically associated with follicular thyroid carcinoma?

    <p>Lymphatic invasion</p> Signup and view all the answers

    What is the primary marker used to monitor patients after the surgical treatment of differentiated thyroid cancers?

    <p>Thyroglobulin</p> Signup and view all the answers

    Which subtype of thyroiditis is primarily autoimmune and often presents with transient hyperthyroidism?

    <p>Chronic lymphocytic thyroiditis</p> Signup and view all the answers

    Which of the following thyroid cancer types has the most aggressive behavior and poor prognosis?

    <p>Anaplastic carcinoma</p> Signup and view all the answers

    In which thyroiditis subtype is the cause primarily viral, often following a recent infection?

    <p>De Quervain's thyroiditis</p> Signup and view all the answers

    What is the correct management step to consider before surgery in patients with medullary thyroid carcinoma who have a RET mutation?

    <p>Exclusion of pheochromocytoma</p> Signup and view all the answers

    What condition may present as a painless thyroid nodule in women aged 30-40 and is often asymptomatic?

    <p>Papillary carcinoma</p> Signup and view all the answers

    Which of the following is a significant risk factor for more aggressive follicular carcinoma?

    <p>Age greater than 50 years</p> Signup and view all the answers

    What is a unique clinical presentation feature of Graves disease?

    <p>Acropachy</p> Signup and view all the answers

    Which of the following is primarily used for symptomatic relief in hyperthyroid patients?

    <p>Propranolol</p> Signup and view all the answers

    In the management of toxic multinodular goiter, what is the primary treatment of choice?

    <p>Radioactive Iodine</p> Signup and view all the answers

    Which condition is characterized by the presence of TSH receptor antibodies?

    <p>Graves Disease</p> Signup and view all the answers

    What laboratory finding is typically observed in a patient with Graves disease?

    <p>Normal TSH with high T3</p> Signup and view all the answers

    Which of the following treatments for hyperthyroidism can lead to agranulocytosis?

    <p>Thionamides</p> Signup and view all the answers

    Which physical examination sign suggests increased pressure in the thoracic inlet?

    <p>Pemberton’s sign</p> Signup and view all the answers

    Graves disease can be definitively diagnosed by which laboratory evaluation?

    <p>TSH receptor antibodies</p> Signup and view all the answers

    What is the most common presenting symptom of toxic multinodular goiter in elderly patients?

    <p>Palpitations</p> Signup and view all the answers

    What clinical feature is associated with thyroid dermopathy in Graves disease?

    <p>Pretibial myxedema</p> Signup and view all the answers

    In diffuse nontoxic goiter, what does the TSH level typically indicate?

    <p>Normal or slightly elevated</p> Signup and view all the answers

    Which autoimmune thyroid condition is characterized by lymphocytic infiltration?

    <p>Painless Lymphocytic Thyroiditis</p> Signup and view all the answers

    What is an expected imaging finding in a thyroid scan for toxic multinodular goiter?

    <p>Heterogeneous uptake</p> Signup and view all the answers

    Study Notes

    Thyroid Gland Hormonal Pathway

    • The hypothalamus releases TRH (thyrotropin-releasing hormone)
    • TRH stimulates the anterior pituitary to release TSH (thyroid stimulating hormone)
    • TSH stimulates the thyroid gland to release T3 (triiodothyronine) and T4 (thyroxine)
    • Thyroid hormones regulate metabolism of fats, proteins, and carbohydrates
    • Thyroid hormones maintain blood pressure, body temperature, and heart rate

    Metabolic Effects of Thyroid Hormones

    • T3 and T4 are catabolic hormones
    • Low levels of thyroid hormones stimulate protein synthesis and increase protein balance
    • Excess thyroid hormones stimulate protein degradation and decrease nitrogen balance
    • Low levels of thyroid hormones stimulate glycogen synthesis and glucose utilization
    • Excess thyroid hormones stimulate glycogenolysis and gluconeogenesis
    • Thyroid hormones increase lipolysis and fatty acid oxidation
    • Thyroid hormones slightly increase cholesterol synthesis but significantly increase clearance, resulting in a net decrease in cholesterol levels

    Thyroid Functions

    • Thyroid hormones increase basal metabolic rate
    • Thyroid hormones control body temperature
    • Thyroid hormones affect protein synthesis
    • Thyroid hormones regulate long bone growth in conjunction with growth hormone
    • Thyroid hormones regulate protein, fat, and carbohydrate metabolism
    • Thyroid gland produces calcitonin, which regulates calcium levels in the body, along with the parathyroid

    Thyroid Functions - T3

    • T3 accounts for about 20 percent of thyroid gland output
    • T3 has a shorter serum half-life than T4
    • T3 is primarily produced through peripheral conversion of T4
    • Cells have eight times more affinity for T3 than T4

    Thyroid Functions - T4

    • T4 accounts for about 80 percent of thyroid gland output
    • T4 has a longer serum half-life than T3
    • T4 is less physiologically active at the cellular level than T3

    Thyroid Function Tests (TFTs)

    • TSH is a hormone produced by the anterior pituitary gland
    • Total T3 includes bound and free T3
    • T3 uptake measures unoccupied thyroid binding globulin (TBG)

    Primary Hypothyroidism - Clinical Presentation

    • Primary hypothyroidism onset is usually insidious
    • Patients may not notice symptoms until euthyroidism is restored
    • Patients with Hashimoto’s thyroiditis may present with goiter rather than symptoms

    Hypothyroidism - Differential Diagnosis

    • Hashimoto’s thyroiditis
    • Subacute thyroiditis
    • Iodine deficiency
    • Post-ablative hypothyroidism
    • Post-surgical hypothyroidism
    • Drug-induced hypothyroidism including amiodarone and lithium

    Thyroiditis - Hashimoto’s disease

    • Hashimoto’s thyroiditis is an autoimmune disease
    • The origin of the disease is a genetic deficiency in antigen-specific suppressor T-cells
    • Cytotoxic T-cells attack follicular cells
    • Unregulated T-helper cell proliferation and B-cell autoantibody production contribute to the disease
    • The presence of anti-thyroid peroxidase antibodies is diagnostic of Hashimoto’s Thyroiditis

    Hashimoto’s Thyroiditis

    • Hashimoto’s thyroiditis is the most common cause of hypothyroidism in North America
    • Incidence is higher in areas with a high dietary iodine intake
    • Smoking increases the risk of Hashimoto’s Thyroiditis
    • Goiter, depression, and chronic fatigue are common symptoms of Hashimoto's thyroiditis
    • Hashimoto's thyroiditis may present alongside other diseases including IBS, celiac disease, Turner's syndrome, hepatitis C, and adrenal insufficiency

    Hashimoto’s Thyroiditis

    • Hashimoto’s thyroiditis can cause early transient hyperthyroidism due to release of stored hormone during the early destructive phase

    Myxedema

    • Myxedema is a severe form of hypothyroidism in adults
    • Myxedema is characterized by dry skin, swelling around the lips and nose, mental deterioration, and subnormal basal metabolic rate
    • Myxedema is characterized by firm inelastic edema, dry skin and hair, and loss of mental and physical vigor
    • Myxedema coma is an emergency with a high mortality rate
    • Myxedema coma is characterized by altered level of consciousness, seizures, other features of hypothyroidism, hypothermia, hypercapnea, and hypoxia

    Primary Hypothyroidism - Diagnostic Evaluation

    • Elevated TSH
    • Decreased free T4
    • Increased thyroid autoantibodies in autoimmune thyroiditis
    • Elevated cholesterol and triglycerides

    Primary Hypothyroidism - Treatment & Monitoring

    • Treatment:
      • Levothyroxine (Synthroid)
      • Dose range: 50-200 mcg PO qd
      • Target dose: Normal TSH
      • Usually lifelong treatment
    • Monitoring:
      • Check TSH every 4-6 weeks after starting treatment or dose change
      • Check TSH every 6-12 months for stable patients with normalized TSH
      • Check TSH every 6 weeks for pregnant patients with hypothyroidism

    Secondary Hypothyroidism

    • Hypothalamic or anterior pituitary gland dysfunction
    • Decreased TSH or dysfunctional TSH leads to decreased T3 and T4
    • Decreased TRH if hypothalamic dysfunction is present

    Secondary Hypothyroidism - Etiology

    • Pituitary adenoma is the most common cause of secondary hypothyroidism
    • Any process that disrupts hypothalamic-pituitary function can cause secondary hypothyroidism

    Secondary Hypothyroidism: Clinical Presentation

    • Symptoms:
      • Similar to primary hypothyroidism
      • Possible symptoms of other pituitary hormone abnormalities
    • Signs:
      • Similar to primary hypothyroidism
      • Possible vision changes, headaches, galactorrhea, skin pigmentation changes, acromegaly

    Secondary Hypothyroidism: Diagnostic Evaluation

    • TSH is low, high, or normal
    • Free T4 is low
    • Serum cortisol, PRL, LH & FSH, total testosterone in men
    • MRI of pituitary gland

    Secondary Hypothyroidism: Treatment & Monitoring

    • Treatment:
      • Thyroxine replacement
      • Endocrine consultation
      • Assessment and management of underlying pituitary pathology
      • Treat pituitary tumor by radiation or transphenoidal resection
      • Treat adrenal insufficiency
    • Monitoring:
      • Endocrinologist monitoring
      • Initial thyroxine dose titration based on free T4 levels 24 hr after last dose then every 4-8 weeks

    Thyroid Nodules

    • Thyroid enlargement (goiter) can be diffuse or irregular (nodular)
    • Nodular goiter is common in regions with iodine deficiency
    • Past history of head/neck irradiation increases the risk of thyroid nodules, including thyroid cancer
    • Palpable solitary nodules are often benign adenomas or colloid nodules
    • Thyroid adenomas can function autonomously, leading to thyrotoxicosis (toxic adenoma)
    • Other thyroid pathology includes primary or metastatic neoplasms, thyroiditis, infections, and cysts

    Evaluation of Thyroid Mass or Enlargement

    • Imaging:
      • Ultrasound of the thyroid gland is the first choice
      • Determine if the nodule is solitary or multiple
      • Follow nodules clinically
      • Guide difficult FNA
    • Thyroid scan with radionuclide study is used for low TSH
    • CT and MRI are used infrequently due to expense and less accuracy compared to ultrasound
    • Tissue:
      • FNA (fine needle aspiration)
      • Open biopsy

    Thyroid Nodule US

    • High suspicion for malignancy: hypoechoic solid nodule with irregular borders and microcalcifications
    • Low suspicion for malignancy: spongiform nodule with microcystic areas comprising over 50 percent of nodule volume

    Thyroid Nodules: Radionucleotide Scan

    • Cold nodules: cells do not synthesize thyroid hormone, do not take up radioactive iodine, appear white on scan
    • Warm nodules: intermediate characteristics
    • Hot nodules: cells synthesize excess thyroid hormones, take up radioactive iodine, appear dark on scan

    The Nodular Thyroid: Diagnostic Evaluation

    • Fine needle aspiration (FNA) biopsy is recommended for suspicious nodules
    • FNA is performed with a 25-gauge needle
    • Care is needed to avoid bloody dilution of the sample

    FNA Indications

    • FNA is recommended for solitary thyroid nodules greater than 5 mm in diameter with suspicious appearance on ultrasound
    • FNA is recommended for nodules associated with abnormal cervical lymph nodes
    • FNA is recommended for nodules ≥ 1 cm in diameter that are solid or have microcalcifications
    • FNA is recommended for mixed cystic-solid nodules greater than 1.5 cm in diameter with suspicious features or greater than 2 cm with benign ultrasound appearance

    The Nodular Thyroid: Treatment Considerations

    • Regular follow-up and re-biopsy as indicated
    • Treatment with levothyroxine for nodules associated with elevated TSH
    • Levothyroxine suppression may increase the risk of angina and arrhythmia in patients with underlying cardiovascular disease
    • Levothyroxine suppression in postmenopausal women may cause loss of bone density

    Solitary Thyroid Nodule: Considerations

    • FNA is indicated for solitary thyroid nodules
    • Cystic nodules should have fluid removed and followed
    • Hyperfunctioning solitary nodules require investigation to distinguish toxic adenoma from Graves’ disease
    • Hot nodules typically benign; remove to cure hyperthyroidism

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma

    • Toxic thyroid adenoma is often a single, large nodule causing hyperthyroidism
    • Toxic thyroid adenoma requires treatment and does not regress spontaneously
    • Symptoms include a choking sensation, dysphagia, and hoarseness
    • Diagnosis is made with a thyroid scan showing a single hot area and suppression of extranodular tissue

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma

    • Treatment options:
      • Beta-blockers for tachycardia
      • Radioactive iodine for non-pregnant patients
      • Subtotal thyroidectomy if necessary
      • Antithyroid drugs in pregnancy:
        • Propylthiouracil in the first trimester
        • Methimazole in the second and third trimesters

    Nonpalpable (Incidental) Thyroid Nodule: Considerations

    • Nonpalpable thyroid nodules are detected in about 50 percent of neck scans
    • FNA is recommended only for nodules larger than 1.5 cm or in patients with a history of head/neck irradiation

    The Nodular Thyroid: Prognosis

    • The vast majority of thyroid nodules are benign
    • Conversion to malignancy is rare
    • Nodules rarely increase in size
    • Multinodular goiters persist or grow slowly
    • Incidental nodules are rarely malignant

    Thyroid Cancer

    • Incidence increases with age
    • Female:Male ratio is 3:1
    • Associated with past history of regional irradiation
    • Accounts for 1,500 deaths annually in the U.S.

    Thyroid Gland Hormonal Pathway

    • The hypothalamus releases TRH (thyrotropin-releasing hormone)
    • The anterior pituitary releases TSH (thyroid stimulating hormone)
    • The thyroid gland releases T3 (triiodothyronine) and T4 (tetraiodothyronine, thyroxine)
    • Thyroid hormones regulate metabolism, body temperature, blood pressure, and heart rate.

    Metabolic Effects of Thyroid Hormones

    • Thyroid hormones influence metabolism of fats, proteins, and carbohydrates.
    • Excess thyroid hormone levels can lead to negative protein balance.
    • Low thyroid hormone levels can stimulate glycogen synthesis and glucose utilization.
    • Low levels increase lipolysis and fatty acid oxidation and decrease cholesterol levels.

    Thyroid Functions

    • Increases the basal metabolic rate
    • Controls body temperature
    • Impacts protein synthesis
    • Regulates long bone growth
    • Regulates metabolism of protein, fat, and carbohydrates
    • Produces calcitonin (regulates calcium levels with parathyroid)

    Thyroid Functions: T3 (Triiodothyronine)

    • Makes up approximately 20% of thyroid gland output
    • Has a shorter serum half-life
    • Most T3 is produced from T4 through enzymatic peripheral conversion by de-iodination
    • Cells have a higher affinity for T3 than T4.

    Thyroid Functions: T4 (Thyroxine)

    • Makes up approximately 80% of thyroid gland output
    • Has a longer serum half-life
    • Less active at the cellular level than T3.

    Thyroid Function Tests (TFTs)

    • TSH is produced by the anterior pituitary gland
    • T3 (total) includes bound and free T3
    • T3 uptake measures unoccupied TBG (inversely related to T3)

    Primary Hypothyroidism

    • Often has an insidious onset.
    • Symptoms may only be recognized when euthyroidism is restored.
    • Patients with Hashimoto’s thyroiditis may present with goiter but not have symptoms.

    Hypothyroidism Differential Diagnosis

    • Hashimoto’s thyroiditis
    • Subacute thyroiditis
    • Iodine deficiency
    • Post-ablative
    • Post-surgical
    • Drugs: Amiodarone, Lithium

    Thyroiditis: Hashimoto’s Disease

    • Thought to result from a genetic deficiency in antigen-specific suppressor T-cells
    • Cytotoxic T cells attack follicular cells
    • Autoantibodies are directed against thyroid cells, colloid components, and thyroid hormones.

    Hashimoto’s Thyroiditis

    • Most common cause of hypothyroidism in North America.
    • More prevalent in those with high dietary iodine intake.
    • Smoking increases the risk of Hashimoto’s thyroiditis.
    • Goiter, depression, and chronic fatigue are common in patients with Hashimoto's thyroiditis.
    • Common co-morbidities include IBS, celiac disease, Turner’s syndrome, hepatitis C, and adrenal insufficiency.
    • May cause early transient hyperthyroidism due to hormone release during the destructive phase.

    Hashimoto’s Thyroiditis: Diagnosis

    • Elevated TSH
    • Low thyroid hormone
    • Presence of anti-thyroid peroxidase antibodies

    Hashimoto’s Thyroiditis: Presentation

    • Marked facial swelling and peri-orbital edema may occur.
    • Associated with dilutional hyponatremia or SIADH syndrome.

    Severe Hypothyroidism: Myxedema

    • Severe form of hypothyroidism in adults
    • Characterized by dry skin, swelling around the lips & nose, mental deterioration, and a subnormal basal metabolic rate
    • Characterized by firm, inelastic edema, dry skin & hair, and loss of mental and physical vigor.

    Myxedema Coma

    • A medical emergency with high mortality rate
    • Altered level of consciousness, seizures, other features of hypothyroidism
    • Hypothermia, hypercapnea, hypoxia

    Primary Hypothyroidism: Diagnostic Evaluation

    • Elevated TSH
    • Decreased free T4
    • Optional: Thyroid autoantibodies (elevated in autoimmune thyroiditis)
    • Many hypothyroid patients have high cholesterol and/or triglycerides.

    Primary Hypothyroidism: Treatment and Monitoring

    • Treatment: Levothyroxine (Synthroid)
    • Treatment: Combination therapy (T3 and T4)
    • Monitoring: Check TSH 4-6 weeks after starting treatment or changing dose
    • Monitoring: Stable patients should target mid-upper range normal free T4 levels.

    Hyperthyroidism

    • Overproduction of thyroid hormones.
    • Etiologies include: Graves Disease, Painless Lymphocytic Thyroiditis, Subacute Thyroiditis, Toxic Thyroid Adenoma, Toxic Multinodular Goiter.

    Graves Disease

    • The most common cause of hyperthyroidism.
    • Pathophysiology: TSH receptor antibodies activate the TSH receptor on the thyroid resulting in increased production of T3 and T4.
    • Unique clinical features: Orbitopathy, Acropachy, Dermopathy (pretibial myxedema)

    Graves Disease: Clinical Presentation

    • Exophthalmos
    • Pretibial myxedema
    • Acropachy

    Graves Disease: Diagnostic Evaluation

    • Decreased TSH
    • Elevated free T3 and T4
    • Elevated TSH receptor antibodies
    • Elevated thyroid radioactive iodine uptake (technetium 99)

    Graves Disease: Treatment and Monitoring

    • Beta-blockers: Propranolol is used for symptomatic relief
    • Antithyroid drugs: Methimazole, Propylthiouracil
    • Radioactive Iodine: Ablates thyroid tissue
    • Thyroidectomy: Total or subtotal.

    Thyromegaly and Goiter: Management

    • Dependent on the underlying cause.
    • Further evaluation is needed to identify the etiology.

    Diffuse Nontoxic (Simple) Goiter

    • More common in women
    • Increased iodine demands associated with pregnancy
    • Most patients asymptomatic

    Diffuse Nontoxic (Simple) Goiter: Clinical Presentation

    • Symmetrically enlarged, non tender, and soft thyroid gland without palpable nodules.
    • May experience symptoms from compression of adjacent tissues.

    Diffuse Nontoxic (Simple) Goiter: Diagnosis

    • Normal or slightly elevated TSH
    • Low total T4, with normal T3
    • TPO antibodies may be present to indicate increased risk of autoimmune thyroid disease
    • Low urinary iodine levels
    • Most common in iodine-deficient regions, but also occurs in iodine sufficient regions.

    Nontoxic Multinodular Goiter (MNG)

    • Multiple nodules of varying sizes
    • Often not possible to palpate all nodules
    • Pemberton’s sign - Facial suffusion when the patient’s arms are elevated above the head.
    • Tracheal deviation is common with inspiratory stridor.

    Nontoxic MNG: Diagnostic Evaluation

    • TSH levels are usually normal.
    • Pulmonary function tests assess the functional effects of tracheal compression.
    • CT or MRI evaluate the anatomy of the goiter and tracheal narrowing.
    • Barium swallow measures the extent of esophageal compression.
    • Ultrasonography identifies nodules that should be biopsied based on size and features.

    Nontoxic MNG: Treatment

    • Most patients can be managed conservatively.
    • Contrast agents and iodine-containing substances should be avoided.
    • Glucocorticoids or surgery may be needed for acute compression.
    • Radioiodine may be used for surgery contraindications.

    Toxic Multinodular Goiter (MNG)

    • Presence of functional autonomy.
    • Patients often elderly
    • Clinical presentation similar to nontoxic MNG in addition to subclinical or mild hyperthyroidism.

    Toxic MNG: Clinical Presentation

    • Atrial fibrillation or palpitations
    • Tachycardia
    • Nervousness
    • Tremor
    • Weight loss
    • Possible history of iodine exposure

    Toxic MNG: Diagnostic Evaluation

    • Low TSH
    • Normal or minimally increased T4
    • Often elevated T3
    • Heterogeneous uptake on thyroid scan
    • US performed to assess the presence of "cold" nodules.

    Toxic MNG: Treatment

    • Antithyroid drugs normalize thyroid function.
    • Radioiodine may be the treatment of choice.
    • Surgery provides definitive treatment.

    Thyroid Nodule

    • New and abnormal growth of tissue
    • Tumor: Benign = not cancerous; Malignant = cancerous
    • Thyroid adenoma: Benign thyroid tumor
    • Thyroid nodule: A thyroid mass - solid or cystic

    Thyroid Nodules

    • 30% females have thyroid nodules by age 30.
    • FNA biopsy is the standard of care for nodules greater than 5mm.
    • US guided FNA.

    FNA Indications

    • Nodules > 5 mm diameter with suspicious US appearance
    • Nodules associated with abnormal cervical lymph nodes
    • Nodules ≥1 cm diameter that are solid or have microcalcifications
    • Mixed cystic-solid nodules >1.5 cm diameter with suspicious features or >2 cm with benign US appearance
    • Spongiform nodules ≥ 2 cm

    The Nodular Thyroid: Management

    • Regular follow-up and re-biopsy as indicated
    • Nodules associated with elevated TSH treated with levothyroxine.

    Solitary Thyroid Nodule

    • FNA indicated
    • Cystic nodules: Remove fluid and follow
    • Associated with hyperthyroidism:
      • Scan to distinguish a toxic adenoma from Graves' disease
      • Hot nodules are usually benign but often removed to cure hyperthyroidism.

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma

    • Single large thyroid nodule causing hyperthyroidism.
    • Requires treatment and does not spontaneously regress.

    Toxic Thyroid Adenoma: Clinical Presentation

    • Possible dysphagia, dyspnea, or hoarseness.
    • Typical hyperthyroid symptoms.
    • Often a palpable thyroid nodule.

    Toxic Thyroid Adenoma: Diagnosis

    • Thyroid scan showing a single "hot" area.

    Toxic Thyroid Adenoma: Treatment

    • Symptomatic treatment (beta-blockers for tachycardia)
    • Radioactive iodine is the treatment of choice (not pregnant).
    • Subtotal thyroidectomy may be necessary.
    • Propylthiouracil during pregnancy (1st trimester)
    • Methimazole during pregnancy (2nd and 3rd trimester)

    Nonpalpable (Incidental) Thyroid Nodule

    • Detected in about 50% of neck scans
    • FNA only if nodule is greater than 1.5cm or history of irradiation.

    The Nodular Thyroid: Prognosis

    • Vast majority are benign
    • Only a 1% increase in size with follow-up
    • Multinodular goiters persist or grow slowly
    • Incidental nodules rarely malignant

    Thyroid Cancer

    • Incidence increases with age
    • Female: Male ratio of 3:1
    • Associated with past history of regional irradiation
    • Accounts for 1500 deaths in the U.S. annually.

    Thyroid Cancer

    • Commonly presents as an asymptomatic thyroid nodule found on palpation or ultrasound in females between 30-40 years old.
    • May be accompanied by painless swelling.
    • Diagnostic evaluation includes:
      • Thyroid function tests are usually normal.
      • Ultrasound for size and location of the mass.
      • Fine Needle Aspiration biopsy (FNA) is a positive indicator.
      • Radioisotope scans for bone metastasis as well as Chest X-Ray (CXR) and Computed Tomography (CT).
      • Thyroglobulin levels can be used as a marker after thyroidectomy as most differentiated thyroid cancers secrete this protein.
    • Treatment involves:
      • Total thyroidectomy.
      • Radioactive iodine ablation.
      • Thyroid-stimulating hormone (TSH) suppression using high-dose levothyroxine (papillary or follicular cancers).
    • Uncommon types like medullary, lymphoma, and anaplastic cancers require tailored treatments.

    Thyroid Cancer Histological Types

    • Papillary:
      • Most common thyroid cancer (80-85%).
      • Well-differentiated and multipolar.
      • Lymphatic invasion and spread.
      • Over 90% 10-year survival rate.
      • Low risk of recurrence and metastasis.
    • Follicular:
      • Makes up 10% of thyroid cancers.
      • Direct hematogenous (blood) invasion and spread with systemic metastasis.
      • Prognosis slightly worse than papillary thyroid cancer.
    • Medullary:
      • Represents 4% of thyroid cancers.
      • Early lymph node spread.
      • 80% 5-year survival rate.
    • Anaplastic:
      • Rare type with short survival time (a few months).
    • Lymphoma:
      • Also rare, with 80% cases in stage I or II.
      • Excellent prognosis for stage I and II cases.
      • Mortality significantly increases in stage IV disease, particularly if distant metastasis is present (1% of patients).

    Follicular Carcinoma (FTC)

    • Accounts for 5-10% of thyroid cancer diagnoses in the US.
    • Generally more aggressive than papillary thyroid cancer.
    • Can secrete enough thyroxine to cause overt thyrotoxicosis.
    • Metastasis is common to neck nodes, bone, lung, and the CNS.
    • Mortality rates are lower than those for papillary thyroid cancer (PTC), partially because a larger proportion of patients present with stage IV disease.
    • Poor prognostic features include:
      • Distant metastases.
      • Age greater than 50 years.
      • Primary tumor size exceeding 4 cm.
      • Hürthle cell histology.
      • Presence of marked vascular invasion.

    Medullary Thyroid Carcinoma (MTC)

    • Represents 3-5% of thyroid cancers.
    • 1/3 are sporadic, typically presenting around 50 years old.
    • The rest are familial, associated with multiple endocrine neoplasia (MEN) types IIA and IIB, or familial MTC without other MEN features.
    • All patients with MTC should be tested for RET mutations.
    • Genetic counseling and testing for family members should be offered to those who test positive for mutations.
    • Management of MTC is primarily surgical.
    • Pheochromocytoma should be excluded in all patients with a RET mutation before surgery.
    • Elevated serum calcitonin is a marker of residual or recurrent disease.

    Thyroiditis

    • Inflammation of the thyroid gland.

    Subtypes of Thyroiditis

    • Chronic Lymphocytic Thyroiditis (Hashimoto's Thyroiditis):
      • Autoimmune-mediated.
    • Subacute Lymphocytic Thyroiditis (Postpartum Thyroiditis):
      • Autoimmune-mediated.
    • Acute Infectious Thyroiditis:
      • Bacterial, parasitic, or fungal.
    • De Quervain's Thyroiditis (Subacute Granulomatous Thyroiditis):
      • Viral-mediated.
    • Riedel's Thyroiditis:
      • Cause is unknown.

    Painless Lymphocytic Thyroiditis

    • Autoimmune-mediated inflammation of the thyroid gland.
    • Clinical Course: Transient hyperthyroidism → Hypothyroidism → Euthyroid state.
      • Progression rates vary.
    • Increased risk in postpartum, lithium treatment, biologic treatment, and cytokine treatment cases.
    • Diagnosis: Radioiodine uptake.
    • Symptoms include dysphagia, dyspnea, hoarseness, and pain.
    • Signs and symptoms may be related to other affected body areas.
    • Diagnostic evaluation involves biopsy.
    • Most patients remain euthyroid.

    Thyroid Gland Hormonal Pathway

    • Hypothalamus releases thyrotropin-releasing hormone (TRH)
    • Anterior pituitary releases thyroid stimulating hormone (TSH)
    • Thyroid gland releases triiodothyronine (T3) and thyroxine (T4)
    • T3 and T4 are major metabolic hormones, affecting fats, proteins, carbohydrates, blood pressure, body temperature, and heart rate

    Metabolic Effects of Thyroid Hormones

    • Calorigenesis: T3 and T4 are the ultimate catabolic hormones
    • Protein Metabolism: Low levels stimulate protein synthesis and positive protein balance, while excess levels stimulate degradation and negative nitrogen balance.
    • Carbohydrate Metabolism: Low levels stimulate glycogen synthesis and glucose utilization, while excess levels stimulate glycogenolysis and gluconeogenesis.
    • Lipid Metabolism: High levels increase lipolysis and fatty acid oxidation, decreasing overall cholesterol.

    Thyroid Functions

    • Increases basal metabolic rate
    • Controls body temperature
    • Affects protein synthesis
    • Helps regulate long bone growth
    • Regulates protein, fat, and carbohydrate metabolism
    • Produces calcitonin, regulating calcium levels

    Thyroid Function Tests (TFTs)

    • TSH: hormone produced by the anterior pituitary
    • T3 (total): bound and free T3
    • T3 uptake: measurement of unoccupied thyroid-binding globulin (TBG), inversely proportional to TBG levels
    • T4 (total): bound and free T4
    • Free T4: unbound T4, biologically active
    • TBG: globulin that binds T3 and T4
    • FTI (free thyroxine index): calculation of total T4 in the face of an abnormal TBG
    • Ultra-sensitive TSH and Free T4: the most accurate measurements of thyroid status

    TSH

    • Acts directly on thyroid tissue to increase thyroxine output
    • Normal range: 0.5 – 4.0 mU/L

    T3

    • Resin T3 (or T4) Uptake: indirect inverse test of serum thyroid-binding proteins (TBP)
    • Normal range Total T3: 75-220 ng/dL

    T4

    • Free vs.total T4: T4 is primarily bound to thyroxine-binding globulin (TBG) in the circulation
    • Normal range fT4: 0.8 – 1.8 ng/dL
    • Normal range T4: 4-11 mcg/dL

    When to Test Thyroid Function

    • Signs of abnormal thyroid gland on physical exam (single or multiple nodules, diffuse enlargement, pain)
    • Symptoms of hyperthyroidism or hypothyroidism
    • Screening tests for all women (every 2-3 years) and all men (every 4-5 years)
    • Screening during pregnancy, postpartum, and neonatal screening
    • Screening on medication (Thyroxine replacement, Anti-thyroid drugs, Post-ablation, Lithium, Amiodarone)

    Hypothyroidism

    • Hypothyroidism: clinical state of underproduction of T3 and T4
    • Primary hypothyroidism (95%): failure of thyroid gland to produce T3 and T4
    • Secondary hypothyroidism (5%): failure of anterior pituitary to produce TSH
    • Subclinical Hypothyroidism: Asymptomatic, mild thyroid failure with normal T3 and T4, and minimal elevation of TSH

    Hypothyroidism: Epidemiology

    • Affects 1% of the general population and 5% of individuals over the age of 60
    • Women are affected more than men
    • Congenital hypothyroidism is among the most common congenital diseases, with an incidence of 1:4000 newborns
    • Increased risk in patients with: family or personal history of autoimmune diseases, postpartum women, primary pulmonary HTN, genetic disorders, medication (lithium, amiodarone), age > 65
    • Iodine deficiency: leading cause of hypothyroidism in developing countries

    Primary Hypothyroidism - Etiology

    • Autoimmune Thyroiditis (Hashimoto disease): Most common
    • Iatrogenic/Damage to thyroid gland: Surgery, radioactive iodine ablation, external irradiation therapy, chemotherapy, drugs and toxins
    • Infiltrative diseases: amyloidosis, sarcoidosis, hemochromatosis, scleroderma

    Primary Hypothyroidism – Clinical Presentation

    • Onset is usually insidious
    • Symptoms may only be apparent when euthyroidism is restored
    • Patients with Hashimoto’s thyroiditis may have goiter, irregular and firm consistency rather than symptoms

    Hypothyroidism - Differential Diagnosis

    • Hashimoto’s thyroiditis
    • Subacute thyroiditis
    • Iodine deficiency
    • Post-ablative
    • Post-surgical
    • Drugs: Amiodarone, Lithium

    Thyroiditis: Hashimoto’s disease

    • Genetic deficiency in antigen-specific suppressor T-cells is the underlying cause
    • Cytotoxic T cells attack follicular cells, and unregulated T-helper cell proliferation & B cell autoantibody production occur
    • Antibodies are directed against follicular cell membranes, colloid components, and the thyroid hormones.

    Hashimoto’s Thyroiditis

    • Most common cause of hypothyroidism in North America
    • Found to be more prevalent in areas with high dietary iodine intake
    • Smoking increases the risk
    • Goiter, depression, and chronic fatigue are common
    • Commonly seen in connection to other diseases: IBS, celiac disease, Turner’s syndrome, hepatitis C, adrenal insufficiency
    • Diagnosis is made with elevated TSH, low thyroid hormone, and presence of anti-thyroid peroxidase antibodies
    • May cause early transient hyperthyroidism by release of stored hormone during the early destructive phase

    Severe Hypothyroidism - Myxedema

    • Severe form of hypothyroidism in adults
    • Characterized by dry skin, swelling around the lips and nose, mental deterioration, and a subnormal basal metabolic rate
    • Characterized by firm inelastic edema, dry skin and hair, and loss of mental and physical vigor.
    • Myxedema coma: HIGH MORTALITY RATE
      • Emergency: Altered level of consciousness, seizures, other features of hypothyroidism, hypothermia, hypercapnea, hypoxia

    Primary Hypothyroidism – Diagnostic Evaluation

    • ↑TSH
    • ↓Free T4
    • Optional: Thyroid Auto Antibodies (↑ in autoimmune thyroiditis)
    • Check for high serum cholesterol and/or triglyceride levels

    Primary Hypothyroidism – Treatment & Monitoring

    • Treatment: Levothyroxine (Synthroid)
      • Start low and increase slowly with the elderly and cardiac patients
      • Given once daily, 1 hour before a meal to maximize absorption
      • Target dose = Normal TSH
      • Usually lifelong treatment

    Primary Hypothyroidism - Treatment & Monitoring

    • Treatment:
      • Supplementation with both T3 and T4 may be superior to just T4 in some cases
        • Armour thyroid
        • Cytomel® (triiodothyronine)
        • “Natural” compounds of T3 or T3/T4

    Primary Hypothyroidism - Treatment & Monitoring

    • Monitoring:
      • Check TSH 4-6 weeks after start of treatment or dose change
      • Target = mid-upper range normal Free T4 levels
      • TSH monitoring = NO VALUE

    Hyperthyroidism

    • Hyperthyroidism: ↑T3 and T4 (overproduction of thyroid hormones)
    • Etiology:
      • Graves Disease: TSH receptor antibodies
      • Painless Lymphocytic Thyroiditis: Autoimmune-mediated inflammation
      • Subacute Thyroiditis: Transient inflammation of thyroid
      • Toxic Thyroid Adenoma: Typically single, large, hormonally active thyroid nodule
      • Toxic Multinodular Goiter (MNG): Most common in older pts

    Graves Disease

    • Most common cause of hyperthyroidism
    • Pathophysiology: TSH receptor antibodies bind and activate the TSH receptor on the thyroid gland, causing increased production of T3 and T4.
    • Signs and symptoms unique to Graves Disease:
      • Orbitopathy
      • Acropachy
      • Dermopathy (pretibial myxedema)

    Graves Disease: Diagnostic Evaluation

    • ↓TSH
    • ↑Free T3 & T4
    • ↑TSH receptor Abs
    • ↑Thyroid radioactive iodine uptake (technetium 99)

    Graves Disease – Treatment & Monitoring

    • Treatment:
      • Beta-Blockers: Propranolol is generally used for symptomatic relief of tachycardia, tremor, diaphoresis, and anxiety until hyperthyroidism is resolved.
      • Antithyroid Drugs: Methimazole 10-30 mg/day PO, Propylthiouracil 150-400 mg/day
      • Thyroid replacement PRN
      • Radioactive Iodine (I-131): Ablates thyroid tissue
      • Thyroidectomy: Total or subtotal

    Thyromegaly & Goiter: Management

    • Management is dependent on underlying etiology
    • Detection of thyroid enlargement on inspection or palpation during physical examination should prompt further evaluation to identify its cause

    Diffuse Nontoxic (Simple) Goiter

    • Epidemiology: Women are affected more than men
    • Clinical Presentation:
      • Most patients are asymptomatic if thyroid function is preserved
      • Physical exam reveals symmetrically enlarged, nontender, and generally soft gland without palpable nodules

    Diffuse Nontoxic (Simple) Goiter

    • Diagnostic Evaluation:
      • TFTs: TSH normal or slightly elevated, low total T4, with normal T3
      • TPO antibodies: Useful to identify patients at increased risk of autoimmune thyroid disease -Low urinary iodine levels

    Nontoxic Multinodular Goiter

    • Physical Examination
      • Thyroid gland is distorted
      • Multiple nodules of varying size can be appreciated
      • Pemberton’s sign: Facial suffusion when the patient’s arms are elevated above the head
        • Suggests that the goiter has increased pressure in the thoracic inlet
      • Tracheal deviation is common - Inspiratory Stridor

    Nontoxic Multinodular Goiter

    • Diagnostic Evaluation:
      • TSH level is usually normal but should be measured to exclude subclinical hyper- or hypothyroidism
      • PFTs: Assess functional effects of tracheal compression
      • CT or MRI: Evaluate anatomy of goiter, extent of substernal extension or tracheal narrowing
      • Barium swallow: Reveal the extent of esophageal compression
      • Ultrasonography: Identify which nodules should be biopsied based on size and sonographic features

    Nontoxic Multinodular Goiter

    • Treatment:
      • Most can be managed conservatively
      • Contrast agents and other iodine-containing substances should be avoided
      • Glucocorticoid treatment or surgery may be needed when acute compression occurs
      • Radioiodine has been used when surgery is contraindicated

    Toxic Multinodular Goiter

    • Pathogenesis of toxic MNG appears to be similar to that of nontoxic MNG
    • Major difference: Presence of functional autonomy in toxic MNG
      • Clinical Presentation: May have subclinical or mild overt hyperthyroidism
      • Patient is usually elderly and may present with: atrial fibrillation or palpitations, tachycardia, nervousness, tremor, weight loss
      • May have history of recent exposure to iodine (contrast dyes or other sources) that precipitated or exacerbate thyrotoxicosis

    Toxic Multinodular Goiter

    • Diagnostic Evaluation:
      • TSH is low
      • T4 normal or minimally increased - T3 often elevated to a greater degree than T4
      • Thyroid scan shows heterogeneous uptake
      • 24-h uptake of radioiodine may not be increased but is usually in the upper normal range
      • US - Should be performed to assess the presence of discrete nodules corresponding to areas of decreased uptake (“cold” nodules)
        • If present, fine-needle aspiration (FNA) may be indicated based on sonographic patterns and size cutoffs
          • The cytology results, if indeterminate or suspicious, may direct the therapy to surgery

    Toxic Multinodular Goiter

    • Treatment:
      • Antithyroid drugs normalize thyroid function
        • Particularly useful in the elderly or ill patients with limited lifespan
      • Radioiodine is generally the treatment of choice
        • Treats areas of autonomy as well as decreasing the mass of the goiter by ablating the functioning nodules
      • Surgery provides definitive treatment of underlying thyrotoxicosis as well as goiter - Patients should be rendered euthyroid using an antithyroid drug before operation

    Thyroid Nodule

    • Neoplasm: new and abnormal growth of tissue
    • Tumor: neoplastic mass
      • Benign: Not malignant, not cancer
      • Malignant: Cancer → Invasive, uncontrolled, metastatic
    • Thyroid adenoma: Benign tumor of thyroid gland
    • Thyroid nodule: A thyroid mass – cystic or solid

    Thyroid Nodules

    • Incidence: Female: Male = 3:1, 30% females at age 30 years.

    Thyroid Nodule Scan

    • Cold Nodule:
      • Cells don't produce thyroid hormones
      • Don't absorb Radioactive Iodine
      • Appear white on scan
      • 85% are benign, 15% malignant
    • Warm Nodule:
      • Intermediate characteristics
      • 90% benign, 10% malignant
    • Hot Nodule:
      • Cells produce excessive thyroid hormones
      • Absorb Radioactive Iodine
      • Appear dark on scan
      • 95% benign, 5% malignant

    Thyroid Nodule Diagnosis

    • Fine Needle Aspiration (FNA) Biopsy:
      • 25-gauge needle
      • Avoid bloody dilution
      • Prepared on a slide, dried, and read by a cytopathologist
      • 70% benign, 10% suspicious, 5% malignant, 15% nondiagnostic
      • US guided FNA is also an option
    • FNA Indications:
      • Nodules >5mm diameter with suspicious US appearance
      • Nodules associated with abnormal cervical lymph nodes (LN)
      • Nodules ≥ 1 cm diameter that are solid or have microcalcifications
      • Mixed cystic-solid nodules >1.5 cm diameter with suspicious features or >2 cm with benign US appearance
      • Spongiform nodules ≥ 2 cm

    Thyroid Nodule Treatment

    • Regular follow-up and re-biopsy as indicated
    • Treat nodules associated with elevated TSH with levothyroxine:
      • Long-term TSH suppression prevents enlargement, but few nodules shrink
      • More useful in younger patients
      • May increase risk for angina and arrhythmia in patients with underlying cardiovascular disease
      • Levothyroxine suppression in postmenopausal women may cause bone density loss

    Solitary Thyroid Nodule Considerations

    • FNA indicated
    • Cystic nodules – Remove the fluid and follow-up
    • Nodules associated with hyperthyroidism:
      • Scan to distinguish toxic adenoma from Graves’ disease, include antithyroid antibody tests
      • "Hot" nodules usually benign, but removed to cure hyperthyroidism

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma

    • Often a single large thyroid nodule causing hyperthyroidism (increased T3 & T4)
    • Requires treatment, doesn't spontaneously regress
    • Signs and Symptoms (H&P):
      • Possible choking sensation, dysphagia, hoarseness
      • Typical hyperthyroid symptoms
      • Often palpable thyroid nodule
    • Diagnosis:
      • Thyroid scan showing single "hot" area and suppression of extranodular tissue

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma Treatment

    • Symptomatic Treatment PRN: (beta-blockers for tachycardia, etc.)
    • Radioactive Iodine is treatment of choice (non-pregnant):
    • Subtotal thyroidectomy (PRN):
    • Antithyroid drugs in pregnancy:
      • Propylthiouracil: first trimester
      • Methimazole: second and third trimester

    Nonpalpable Thyroid Nodule Considerations

    • Detected in about 50% of neck scans like MRI, CT, or US done for other reasons
    • FNA only if the nodule is larger than 1.5cm or in prior history of head/neck irradiation

    Thyroid Nodule Prognosis

    • Vast majority are benign, conversion is rare
    • Only 1% increase in size with follow-up
    • Multinodular goiters persist or grow slowly
    • Incidental nodules rarely malignant

    Thyroid Cancer

    • Epidemiology:
      • Incidence increases with age
      • Female:Male ratio is 3:1
      • Associated with past history of regional irradiation
      • Accounts for 1500 deaths in the U.S.

    Thyroid Function Tests

    • Total T4 measures bound and free T4.
    • Free T4 is unbound and biologically active.
    • TBG binds T3 and T4.
    • FTI (Free Thyroxine Index) corrects for abnormal TBG levels by multiplying total T4 by T3 uptake and dividing by 100.
    • Ultra-sensitive TSH and Free T4 are the most accurate measurements of thyroid status.

    TSH

    • Thyroid Stimulating Hormone (TSH) directly stimulates the thyroid gland to produce thyroxine.
    • Normal TSH range is 0.5 - 4.0 mU/L.
    • Third-generation TSH assays are sensitive to 0.01.

    T3

    • Resin T3 uptake is an indirect inverse test of serum thyroid-binding proteins (TBP).
    • High resin uptake indicates low serum TBP or high T4 levels.
    • It is used to correct total T4 for the effect of high or low TBP.
    • Normal range of total T3 is 75-220 ng/dL.

    T4

    • Peripheral T4 primarily binds to thyroxine-binding globulin (TBG) in circulation.
    • Normal range for free T4 is 0.8 – 1.8 ng/dL.
    • Normal range for T4 is 4-11 mcg/dL.

    When to Test Thyroid Function

    • A physical exam revealing abnormal thyroid gland including single or multiple nodules, diffuse enlargement, or pain.
    • Symptoms of hyperthyroidism or hypothyroidism.
    • Screening tests for all women every 2-3 years & for all men every 4-5 years.
    • Screening for women during pregnancy and postpartum, and for newborns.
    • Screening for patients on medication such as thyroxine replacement (every 6 months if stable), anti-thyroid drugs (thionamides), post-ablation, lithium, and amiodarone (high iodine content).

    Hypothyroidism

    • Hypothyroidism is the clinical state of underproduction of T3 and T4 hormones.
    • 95% of hypothyroidism cases are primary hypothyroidism - the thyroid gland fails to produce T3 and T4.
    • 5% of cases are secondary hypothyroidism - the anterior pituitary gland fails to produce TSH.
    • Subclinical hypothyroidism is asymptomatic but features mild thyroid failure with normal T3 and T4 levels and minimally elevated TSH.

    Hypothyroidism: Epidemiology

    • Affects about 1% of the general population and 5% of individuals over 60 years old.
    • 0.3% of the US population has primary hypothyroidism.
    • 4.3% of the US population has subclinical hypothyroidism.
    • Most common in Caucasians and women and prevalence increases with age.
    • Women are more affected than men.
    • Congenital hypothyroidism is one of the most common congenital diseases, affecting approximately 1 in 4,000 newborns.
    • Increased risk seen in people with a family or personal history of autoimmune diseases, women in the postpartum period, primary pulmonary HTN, genetic disorders, medication use (lithium, amiodarone), and those over 65 years old.
    • Iodine deficiency is the leading cause of hypothyroidism in developing countries.
    • Iodized salt has reduced the incidence of hypothyroidism.

    Primary Hypothyroidism: Etiology

    • Autoimmune Thyroiditis (Hashimoto disease) is the most common cause.
    • The annual mean incidence rate is 4/1000 women and 1/1000 men.
    • It is most prevalent between ages 30-50 years.
    • 6% of postpartum women experience a transient form of Hashimoto's.
    • Iatrogenic/Damage to thyroid gland stemming from surgery, radioactive iodine ablation, external irradiation therapy, chemotherapy, or exposure to drugs and toxins such as iodine excess, lithium, antithyroid drugs, etc.
    • Infiltrative diseases such as amyloidosis, sarcoidosis, hemochromatosis, and scleroderma.

    Primary Hypothyroidism: Clinical Presentation

    • The onset is usually insidious.
    • Patients may become aware of symptoms only when euthyroidism is restored.
    • Patients with Hashimoto's thyroiditis may present with a goiter (firm, irregular consistency) instead of experiencing symptoms.

    Primary Hypothyroidism: Diagnosis & Treatment

    • Elevated TSH.
    • Decreased Free T4.
    • Thyroid auto-antibodies are elevated in autoimmune thyroiditis.
    • Many hypothyroid patients have high serum cholesterol and/or triglyceride levels, so screening is recommended.
    • Treatment with levothyroxine (Synthroid) is usually lifelong.
    • Start at a low dose (1.6 mcg/kg) and increase gradually with age and cardiac patients.
    • Optimum absorption is achieved by taking the medication 1 hour before a meal.
    • Target dose should result in normalized TSH levels.
    • Current research indicates that supplementation with both T3 and T4 may be superior to just T4 because some individuals do not consistently convert T4 to T3.

    Secondary Hypothyroidism

    • Occurs due to hypothalamic or anterior pituitary gland dysfunction.
    • Decreased TSH, dysfunctional TSH, or decreased TRH result in reduced T3 and T4 production.

    Secondary Hypothyroidism: Etiology

    • Pituitary adenoma.
    • Any process that disrupts hypothalamic-pituitary function (e.g., mass, infection, trauma, surgery, cerebrovascular accident (CVA), radiation, ischemia, and cancer).

    Secondary Hypothyroidism: Clinical Presentation

    • Symptoms are the same as primary hypothyroidism with possible symptoms of other pituitary hormone abnormalities.
    • Signs are the same as primary hypothyroidism with possible vision changes, headaches, galactorrhea, skin pigmentation changes, and acromegaly.

    Secondary Hypothyroidism: Diagnosis & Treatment

    • TSH may be low, high, or normal.
    • Free T4 is always low.
    • Serum cortisol, prolactin (PRL), LH & FSH, and total testosterone in men should be assessed.
    • MRI of the pituitary gland is essential, CT scan is an alternative.
    • Treatment involves thyroxine replacement (same as primary hypothyroidism) and an endocrine consult.
    • Management of underlying pituitary pathology is paramount.

    Thyroid Nodules

    • Enlarged thyroid gland (goiter) can be diffused or irregular (nodular).
    • Nodular goiter is common in regions with iodine deficiency.
    • A history of regional irradiation increases the risk of thyroid nodules, including a greater chance of thyroid cancer.
    • Palpable solitary nodules are often benign adenomas or colloid nodules.
    • Sometimes thyroid adenomas can function autonomously, leading to thyrotoxicosis (toxic adenoma).
    • Other possible causes of thyroid nodules include primary or metastatic neoplasms, thyroiditis, infections, and cysts.

    Evaluation of Thyroid Mass or Enlargement

    • Ultrasound of the thyroid:
      • First choice for imaging, it can determine if the nodule is single or multiple.
      • Used to clinically follow nodules and guide difficult FNAs.
    • Thyroid Scan:
      • Used if TSH is decreased.
      • Identifies "hot nodules" and distinguishes between Grave's disease and thyroiditis.
      • FNAs are now performed more often than radioactive iodine (RAI) scans.
    • CT, MRI:
      • Seldom used due to cost and less accuracy compared to ultrasound.
    • Tissue Biopsy:
      • FNA biopsy is the preferred method.
      • Open biopsy is performed occasionally.

    Thyroid Nodules: Radionucleotide Scan

    • Cold Nodule:
      • Cells do not synthesize thyroid hormones.
      • Do not take up radioactive iodine.
      • Appear white on the scan.
      • 85% are benign, 15% are malignant.
    • Warm Nodule:
      • Intermediate characteristics.
      • 90% are benign, 10% are malignant.
    • Hot Nodule:
      • Cells synthesize excessive thyroid hormones.
      • Take up radioactive iodine.
      • Appear dark on the scan.
      • 95% are benign, 5% are malignant.

    The Nodular Thyroid: Diagnostic Evaluation

    • Fine needle aspiration (FNA) biopsy:
      • Using a 25-gauge needle.
      • Care is needed to avoid bloody dilution.
      • The sample is prepared on a slide, dried, and read by an experienced cytopathologist.
      • 70% benign, 10% suspicious, 5% malignant, 15% non-diagnostic.
      • Ultrasound-guided FNA is often used.

    FNA Indications

    • For solitary thyroid nodules, FNA is indicated for:
      • Nodules larger than 5mm in diameter with suspicious appearance on ultrasound.
      • Nodules associated with abnormal cervical lymph nodes.
      • Nodules greater than or equal to 1 cm in diameter that are solid or have microcalcifications.
      • Mixed cystic-solid nodules larger than 1.5 cm in diameter with suspicious features or larger than 2 cm with benign ultrasound appearance.
      • Spongiform nodules greater than or equal to 2 cm in diameter.

    The Nodular Thyroid: Treatment Considerations

    • Regular follow-up and re-biopsy as needed.
    • Treatment of nodules associated with elevated TSH levels with levothyroxine.
    • Long-term suppression of TSH keeps nodules from enlarging, but few actually shrink.
    • This is more helpful for younger patients.
    • Care must be taken when treating patients with underlying cardiovascular disease, as levothyroxine suppression may increase the risk of angina and/or arrhythmia.
    • Levothyroxine suppression in postmenopausal women may cause loss of bone density.

    Solitary Thyroid Nodule: Considerations

    • FNA is indicated for solitary thyroid nodules.
    • Cystic nodules: Remove the fluid and follow up.
    • Nodules associated with hyperthyroidism:
      • Perform a scan to differentiate between toxic adenoma and Graves’ disease, and include antithyroid antibody tests.
      • "Hot nodules" are typically benign but are removed to cure the hyperthyroidism.

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma

    • Often involves a single, enlarged thyroid nodule that causes hyperthyroidism (increased T3 & T4).
    • Requires treatment and does not spontaneously regress.
    • History and physical exam:
      • May report a choking sensation, dysphagia, and/or hoarseness.
      • Exhibit typical hyperthyroid symptoms.
      • Often a palpable thyroid nodule is present.
    • Diagnosis:
      • Thyroid scan showing a single "hot" area and suppression of extra nodular tissue.

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma - Treatment

    • Symptomatic treatment as needed (e.g., beta-blockers for tachycardia).
    • Radioactive iodine is the treatment of choice for non-pregnant patients.
    • Subtotal thyroidectomy may be necessary in some cases.
    • Antithyroid drugs are used in pregnancy:
      • Propylthiouracil (PTU) is preferred during the first trimester.
      • Methimazole is used in the second and third trimesters.

    Nonpalpable (Incidental) Thyroid Nodule: Considerations

    • Detected in approximately 50% of neck scans (e.g., MRI, CT, or ultrasound) performed for other reasons.
    • FNA is only indicated if the nodule is greater than 1.5 cm in diameter or if the patient has a history of head/neck irradiation.

    The Nodular Thyroid: Prognosis

    • The vast majority of thyroid nodules are benign, and conversion to malignancy is rare.
    • Only 1% of nodules increase in size with follow-up.
    • Multinodular goiters persist or grow slowly.
    • Incidental nodules are rarely malignant.

    Thyroid Cancer

    • The incidence increases with age.
    • The female-to-male ratio is 3:1.
    • A history of regional irradiation increases the risk.
    • Accounts for approximately 1,500 deaths in the US annually.

    Hypothyroidism

    • TSH should be checked every 6-12 months in patients with normal TSH levels.
    •  Pregnant patients who have been diagnosed with hypothyroidism should have their TSH checked every 6 weeks.
    •  Hypothyroid symptoms persisting after treatment initiation with normal thyroid levels may indicate coexisting conditions such as adrenal insufficiency, hypogonadism, anemia, or depression.

    Secondary Hypothyroidism

    •  Secondary hypothyroidism occurs due to hypothalamic or anterior pituitary gland dysfunction.
    •  In secondary hypothyroidism, low or dysfunctional TSH leads to low T3 and T4 levels.
    •  Low TRH levels may indicate hypothalamic dysfunction or abnormality.

    Secondary Hypothyroidism Etiology

    •  The most common cause of secondary hypothyroidism is pituitary adenoma.
    •  Any process disrupting the hypothalamic-pituitary function can cause secondary hypothyroidism including masses, infections, trauma, surgery, CVA, radiation, ischemia, and cancer.

    Secondary Hypothyroidism Clinical Presentation

    •  Symptoms are similar to those of primary hypothyroidism.
    •  Additional symptoms may include other pituitary hormone abnormalities.
    •  Signs are similar to those of primary hypothyroidism.
    •  Other possible signs include vision changes, headaches, galactorrhea, skin pigmentation changes, and acromegaly.

    Secondary Hypothyroidism Diagnostic Evaluation

    •  TSH levels can be low, high, or normal.
    •  Free T4 is low.
    •  Serum cortisol, PRL, LH & FSH, and total testosterone (men) should be checked.
    •  MRI of the pituitary gland is recommended, CT scans can be an alternative.

    Secondary Hypothyroidism Treatment and Monitoring

    •  Treatment includes thyroxine replacement (same as primary hypothyroidism), an endocrine consultation, and assessment and management of underlying pituitary pathology.
    •  Assessment and management of underlying pituitary pathology includes treating any pituitary tumor, for example radiation, transphenoidal resection, and treating adrenal insufficiency.
    •  Monitoring should be done by an endocrinologist.
    •  Initial thyroxine dose titration is based on free T4 levels 24 hours after the last dose and then every 4-8 weeks.
    •  The target free T4 level is in the mid-upper range of normal.
    •  TSH monitoring is not valuable in secondary hypothyroidism.

    Hyperthyroidism

    •  Hyperthyroidism involves an overproduction of thyroid hormones, resulting in elevated T3 and T4 levels.
    •  The main causes of hyperthyroidism include Graves disease, painless lymphocytic thyroiditis, subacute thyroiditis, toxic thyroid adenoma, and toxic multinodular goiter (MNG).

    Graves Disease

    •  The most common cause of hyperthyroidism.
    •  Pathophysiology: TSH receptor antibodies bind to and activate the TSH receptor on the thyroid gland, causing increased production of T3 and T4.
    •  Signs and symptoms unique to Graves disease include orbitopathy, acropachy, and dermopathy (pretibial myxedema).

    Graves Disease: Ophthalmopathy

    •  Features: upper eyelid retraction, lid lag, swelling, erythema, conjunctivitis, and bulging eyes (exophthalmos).

    Graves Disease: Acropachy

    •  Features: Soft-tissue swelling of the hands and clubbing of the fingers.

    Graves Disease: Pretibial myxedema

    •  Features: Skin lesions or areas of non-pitting edema on the anterior or lateral aspects of the legs or in sites of old or recent trauma.

    Graves Disease: Diagnostic Evaluation

    •  Low TSH.
    •  Elevated Free T3 and T4.
    •  Elevated TSH receptor antibodies.
    •  Elevated thyroid radioactive iodine uptake (technetium 99).

    Graves Disease: Treatment and Monitoring

    •  Treatment includes beta-blockers such as propranolol for symptomatic relief of tachycardia, tremor, diaphoresis, and anxiety until hyperthyroidism is resolved, antithyroid drugs like methimazole and propylthiouracil, thyroid replacement PRN, radioactive iodine (I-131) to ablate thyroid tissue, and thyroidectomy (total or subtotal).

    Thyromegaly & Goiter: Management

    •  Management depends on the underlying etiology.
    •  The detection of thyroid enlargement on inspection or palpation during physical examination should prompt further evaluation to identify its cause.

    Diffuse Nontoxic (Simple) Goiter

    •  More common in women than men.
    •  Greater prevalence of underlying autoimmune disease.
    •  Increased iodine demands associated with pregnancy.
    •  Most patients are asymptomatic if thyroid function is preserved.
    •  Physical examination reveals a symmetrically enlarged, nontender, and generally soft gland without palpable nodules.

    Diffuse Nontoxic (Simple) Goiter: Diagnostic Evaluation

    •  TSH levels are normal or slightly elevated, low total T4, with normal T3 (reflecting enhanced T4 → T3 conversion).
    •  TPO antibodies are useful for identifying patients at increased risk for autoimmune thyroid disease.
    •  Low urinary iodine levels.

    Nontoxic Multinodular Goiter

    •  More prevalent with age.
    •  Most common in iodine-deficient regions, but also occurs in regions of iodine sufficiency, influenced by genetic, autoimmune, and environmental factors.
    •  Typically wide variation in nodule size.
    •  Wide spectrum of morphologies ranging from hypercellular, hyperplastic regions to cystic areas filled with colloid.

    Nontoxic Multinodular Goiter: Physical Examination

    - Thyroid gland is distorted. - Multiple nodules of varying sizes can be appreciated. - Pemberton's sign (facial suffusion when the patient's arms are elevated above the head) suggests increased pressure in the thoracic inlet. - Tracheal deviation is common and can cause inspiratory stridor.

    Nontoxic Multinodular Goiter: Diagnostic Evaluation

    •  TSH levels are usually normal, but should be measured to exclude subclinical hyper- or hypothyroidism.
    •  PFTs assess the functional effects of tracheal compression.
    •  CT or MRI evaluate the anatomy of the goiter and the extent of substernal extension or tracheal narrowing.
    •  Barium swallow reveals the extent of esophageal compression.
    •  Ultrasonography identifies the nodules that should be biopsied based on size and sonographic features.

    Nontoxic Multinodular Goiter: Treatment

    •  Most patients can be managed conservatively.
    •  Contrast agents and other iodine-containing substances should be avoided.
    •  Glucocorticoid treatment or surgery may be needed for acute compression.
    •  Radioiodine can be used when surgery is contraindicated in areas where large nodular goiters are more prevalent.

    Toxic Multinodular Goiter

    •  Pathogenesis similar to nontoxic MNG except for the presence of functional autonomy.
    •  Clinical presentation: In addition to goiter features, patients may experience subclinical or mild overt hyperthyroidism, atrial fibrillation or palpitations, tachycardia, nervousness, tremor, and weight loss.
    •  History of recent exposure to iodine may precipitate or exacerbate thyrotoxicosis.

    Toxic Multinodular Goiter: Diagnostic Evaluation

    •  TSH levels are low.
    •  T4 levels are normal or minimally increased.
    •  T3 levels are often elevated to a greater degree than T4.
    •  Thyroid scan shows heterogeneous uptake (multiple regions of increased and decreased uptake).
    •  24-hour uptake of radioiodine may not be increased, but is usually in the upper normal range.
    •  US should be performed to assess the presence of discrete nodules corresponding to areas of decreased uptake ("cold" nodules).
    •  FNA may be indicated for indeterminate or suspicious cytology results and directs therapy to surgery.

    Toxic Multinodular Goiter: Treatment

    •  Antithyroid drugs can normalize thyroid function.
    •  Radioiodine is the generally preferred treatment.
    •  Surgery provides definitive treatment of underlying thyrotoxicosis and goiter.

    Thyroid Nodule

    •  Neoplasm: A new and abnormal growth of tissue.
    •  Tumor: A neoplastic mass.
    •  Benign: Not malignant, not cancer.
    •  Malignant: Cancer, invasive, uncontrolled, metastatic.
    •  Thyroid adenoma: Benign tumor of the thyroid gland (adenoma = benign tumor of glandular tissue).
    •  Thyroid nodule: A thyroid mass – cystic or solid (could be benign or malignant).

    Thyroid Nodules

    •  Incidence: Female to male ratio is 3:1.
    •  30% of females at age 30 have nodules detectable by US or autopsy.
    •  50% of females at age 50 have nodules.
    •  Detection: 40% self, 30% physician, 30% incidentally found on imaging.
    •  Malignancy: ~10% of ultrasound-detected nodules are malignant.

    Evaluation of Thyroid Mass or Enlargement

    •  Ultrasound of the thyroid is the first choice for imaging: determines if one or multiple nodules are present, allows for clinical follow-up of nodules, and guides difficult FNAs.
    •  Thyroid scan (radionucleotide study) is used if TSH levels are low: used to identify “hot nodules”, distinguish between Graves disease and thyroiditis, and FNAs are now used more than RAI scans.
    •  CT and MRI are seldom used due to expense and because US is more accurate.
    •  Obtain tissue by FNA (preferred), open biopsy may be done PRN.

    Thyroid Nodule US

    •  High suspicion ultrasound pattern for thyroid malignancy: hypoechoic solid nodule with irregular borders and microcalcifications.
    •  Very low suspicion ultrasound pattern for thyroid malignancy: spongiform nodule with microcystic areas comprising over 50% of nodule volume.

    Thyroid Nodules: Radionucleotide Scan

    •  Cold (85%) nodule: cells do not synthesize thyroid hormones (tissue is more abnormal), do not take up radioactive iodine, appear white on thyroid scan, and are 85% benign (15% malignant).
    •  Warm (10%) nodule: Intermediate characteristics, 90% benign (10% malignant).
    •  Hot (5%) nodule: Cells synthesize excess thyroid hormones, take up radioactive iodine, appear dark on thyroid scan, and are 95% benign (5% malignant).

    The Nodular Thyroid: Diagnostic Evaluation

    •  FNA biopsy: done using a 25-gauge needle, care is taken to avoid bloody dilution, prepared on a slide, dried, and read by an experienced cytopathologist, 70% benign, 10% suspicious, 5% malignant, and 15% nondiagnostic.
    •  US guided FNA.

    FNA Indications

    •  For solitary thyroid nodules, FNA is indicated for: - Nodules >5mm diameter with suspicious appearance on US. - Nodules associated with abnormal cervical LN. - Nodules ≥ 1 cm diameter that are solid or have microcalcifications. - Mixed cystic-solid nodules >1.5 cm diameter with suspicious features or >2 cm with benign U/S appearance. - Spongiform nodules ≥ 2 cm.

    The Nodular Thyroid: Treatment Considerations

    •  Regular follow-up and re-biopsy as indicated.
    •  Treating nodules associated with elevated TSH with levothyroxine: long-term suppression of TSH tends to keep nodules from enlarging, but few actually shrink; more useful in younger patients; take care in treating patients with underlying cardiovascular disease (may increase risk for angina and/or arrhythmia); levothyroxine suppression in postmenopausal women may cause loss of bone density.

    Solitary Thyroid Nodule: Considerations

    •  Solitary thyroid nodules: - FNA is indicated. - Cystic nodules: Removal of the fluid and follow up. - Associated with hyperthyroidism: - Scan to distinguish toxic adenoma from Graves' disease and include antithyroid antibody tests. - “Hot” nodules are usually benign, but are removed to cure hyperthyroidism.

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma

    •  Toxic thyroid adenoma often involves a single large thyroid nodule causing hyperthyroidism (elevated T3 & T4), and often does not regress spontaneously.
    •  History and physical: possible complaint of choking sensation, dysphagia, hoarseness, or typical hyperthyroid symptoms.
    •  Diagnosis: Thyroid scan showing a single "hot" area and suppression of extranodular tissue.

    Hyperfunctioning Solitary Nodule: Toxic Thyroid Adenoma: Treatment

    •  Symptomatic treatment PRN (beta-blockers for tachycardia, etc.).
    •  Radioactive iodine for non-pregnant patients.
    •  Subtotal thyroidectomy PRN.
    •  Antithyroid drugs in pregnancy: Propylthiouracil is preferred in the first trimester, and methimazole in the second and third trimesters.

    Nonpalpable (Incidental) Thyroid Nodule: Considerations

    •  Nonpalpable thyroid nodules: detected in about 50% of neck scans like MRI, CT, or US done for other reasons.
    •  FNA only if the nodule is found to be larger than 1.5 cm or if the patient has a history of head/neck irradiation.

    The Nodular Thyroid: Prognosis

    •  Vast majority of thyroid nodules are benign.
    •  Only 1% thyroid nodule increase in size with follow up.
    •  Multinodular goiters persist or grow slowly.
    •  Incidental nodules are rarely malignant.

    Thyroid Cancer

    •  Epidemiology: Incidence increases with age, female to male ratio is 3:1, associated with past history of regional irradiation, and accounts for 1500 deaths in the U.S.

    Thyroid Cancer

    • Most commonly found as asymptomatic thyroid nodule during palpation or ultrasound in women between 30-40 years of age
    • TFTs are usually normal
    • Ultrasound determines size and location of masses
    • FNA biopsy is positive in cancer cases
    • Radioisotope scans can check for bone metastases, as well as CXR and CT
    • Thyroglobulin is secreted by most differentiated thyroid cancers and can be used as a marker after thyroidectomy
    • Treatment includes total thyroidectomy + radioactive iodine ablation + TSH suppression (high dose levothyroxine for papillary or follicular cancers)
    • Tailored treatment for uncommon types such as medullary, lymphoma, and anaplastic cancers

    Thyroid Cancer Histological Types

    • Papillary is most common (80-85%)
    • Papillary is usually well differentiated and multifocal
    • Papillary can invade and spread via lymph nodes
    • Papillary has greater than 90% 10-year survival rate, recurrence, and metastasis risk is low
    • Follicular accounts for 10%
    • Follicular invades and spreads via the bloodstream, often with systemic metastasis
    • Follicular has a slightly worse prognosis than papillary
    • Medullary accounts for 4%
    • Medullary has early lymph node spread
    • Medullary has 80% 5-year survival rate
    • Anaplastic is rare and survival rate is a few months
    • Lymphoma is rare (80% stages I or II) and has an excellent prognosis
    • Stage IV Lymphoma has an increased mortality rate, especially with distant metastases

    Follicular Carcinoma (FTC)

    • Accounts for 5-10% of thyroid cancers diagnosed in the US
    • More aggressive than papillary thyroid CA
    • Can secrete enough thyroxine to cause overt thyrotoxicosis
    • Metastasis common to neck nodes, bone, lung, and CNS
    • Mortality rates are less favorable than PTC, due to a larger proportion of patients presenting with stage IV disease
    • Poor prognostic features include:
      • Distant metastases
      • Age over 50 years
      • Primary tumor size greater than 4 cm
      • Hürthle cell histology
      • Presence of marked vascular invasion

    Medullary Thyroid Carcinoma

    • Accounts for 3-5% of thyroid cancers
    • One-third are sporadic, with onset around 50 years of age
    • The remainder are familial and associated with MEN IIA and IIB or familial MTC without other features of MEN
    • All patients with MTC should be tested for RET mutations, allowing genetic counseling and testing for family members who test positive for mutations.
    • Management of MTC is primarily surgical, but pheochromocytoma should be excluded in all patients with a RET mutation prior to surgery
    • Elevated serum calcitonin is a marker of residual or recurrent disease

    Thyroiditis

    • Inflammation of the thyroid gland

    Subtypes of Thyroiditis

    • Chronic lymphocytic thyroiditis, hashimoto’s thyroiditis, chronic autoimmune thyroiditis, lymphadenoid goiter: Autoimmune
    • Subacute lymphocytic thyroiditis, postpartum thyroiditis, sporadic painless thyroiditis, silent sporadic thyroiditis: Autoimmune
    • Acute infectious thyroiditis, Microbial inflammatory thyroiditis, suppurative thyroiditis, pyrogenic thyroiditis, bacterial thyroiditis: Bacterial, Parasitic, Fungal
    • De Quervain’s thyroiditis, subacute granulomatous thyroiditis, Giant-cell thyroiditis, painful subacute thyroiditis: Viral
    • Riedel’s thyroiditis, Riedel’s struma, Invasive fibrous thyroiditis: Unknown

    Painless Lymphocytic Thyroiditis

    • Autoimmune-mediated inflammation of the thyroid gland
    • Clinical Course: Transient Hyperthyroidism → Hypothyroidism → Euthyroid state
    • Various rates of progression
    • Increased risks: Postpartum, lithium Tx, biologics Tx, cytokine Tx
    • Diagnosis: Radioiodine uptake, dysphagia, dyspnea, hoarseness, pain
    • Signs and symptoms related to other affected body areas
    • Diagnostic Evaluation: Biopsy
    • Clinical Course: Most patients remain euthyroid

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    Test your understanding of the hormonal pathways involving the thyroid gland. This quiz covers the effects of TRH, TSH, and the metabolic roles of T3 and T4. Assess your knowledge of how thyroid hormones influence metabolism and physiological functions.

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