Week 6 NUR 425 Review Questions
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Which hormone is the most abundant in the thyroid gland?

  • Tri-iodothyronine (T3)
  • Calcitonin
  • Thyroid-Stimulating Hormone (TSH)
  • Thyroxine (T4) (correct)

    • What effects does T3 and T4 have on the body? (SATA)

  • Stimulating the adrenal glands
  • Oxygen consumption (correct)
  • Growth and development (correct)
  • Increasing metabolic activity (correct)

    • Which of the following elements is necessary for the synthesis of thyroid hormones?

  • Magnesium
  • Calcium
  • Iodine (correct)
  • Potassium

    • What is the most common cause of hyperthyroidism?

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

    What is the role of thyroid-stimulating immunoglobulins (TSI) in Graves’ disease?

    <p>They mimic TSH and stimulate the thyroid gland</p> Signup and view all the answers

    Which of the following is a potential complication of untreated hyperthyroidism?

    <p>Thyrotoxic crisis</p> Signup and view all the answers

    What is the primary goal of pharmacotherapy for hypothyroidism?

    <p>Restore euthyroid state</p> Signup and view all the answers

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

    <p>With any dose changes in levothyroxine, TSH levels should be checked in 4-6 weeks to assess efficacy</p> Signup and view all the answers

    What is a potential complication of untreated hypothyroidism?

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

    What is the iodine uptake percentage associated with Graves' disease in a 24-hour radioactive iodine uptake (RAIU) test?

    <p>35-90%</p> Signup and view all the answers

    Which of the following lab values would indicate hyperthyroidism?

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

    What is one of the primary treatment options for managing hyperthyroidism?

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

    Which symptom is not typically associated with hyperthyroidism?

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

    What happens to TSH levels when hyperthyroidism is present?

    <p>They decrease</p> Signup and view all the answers

    What is the role of thionamides in the treatment of hyperthyroidism?

    <p>They inhibit thyroid hormone synthesis</p> Signup and view all the answers

    What is the main cause of thyrotoxicosis in Graves' disease?

    <p>Continuous stimulation by TSIs</p> Signup and view all the answers

    Which clinical manifestation is NOT typically associated with Graves' disease?

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

    Which of the following symptoms is specifically linked to thyrotoxic crisis?

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

    What distinguishes exophthalmos from other eye conditions?

    <p>It involves fluid accumulation behind the eyes</p> Signup and view all the answers

    Which option is a common trigger that can lead to thyrotoxic crisis?

    <p>Stressful events like surgery</p> Signup and view all the answers

    What is the primary mechanism through which TSIs contribute to hyperthyroidism?

    <p>Acting as agonists at TSH receptors</p> Signup and view all the answers

    Which symptom indicates increased activity of the gastrointestinal system in hyperthyroidism?

    <p>Increased bowel movements</p> Signup and view all the answers

    What is pretibial myxedema commonly associated with?

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

    Which treatment option is most effective for managing thyrotoxic crisis?

    <p>Antithyroid medications</p> Signup and view all the answers

    What is the expected timeframe for seeing significant lab result changes after starting antithyroid medication treatment for hyperthyroidism?

    <p>Up to 12 weeks</p> Signup and view all the answers

    Which medication is preferred for long-term management of hyperthyroidism due to its lower risk of agranulocytosis?

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

    What are some symptoms that β-blockers like Propranolol can relieve in patients experiencing thyrotoxicosis?

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

    Which of the following is a recognized early indicator of agranulocytosis in patients undergoing treatment for hyperthyroidism?

    <p>Fever and sore throat</p> Signup and view all the answers

    What is the primary action of iodine therapy in the treatment of hyperthyroidism?

    <p>It inhibits synthesis of T3 and T4 and blocks their release.</p> Signup and view all the answers

    In which of the following conditions is Propylthiouracil (PTU) primarily indicated for use?

    <p>Pregnancy during the first trimester</p> Signup and view all the answers

    What complication can occur following subtotal thyroidectomy related to damage to the parathyroid glands?

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

    Which patient group should avoid Radioactive Iodine Therapy (RAI)?

    <p>Pregnant women</p> Signup and view all the answers

    What dietary changes might be recommended for a patient with hyperthyroidism due to an overactive gastrointestinal tract?

    <p>May need a high-calorie diet</p> Signup and view all the answers

    What is the most common cause of hypothyroidism worldwide?

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

    Which clinical manifestation is associated with longstanding hypothyroidism?

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

    How can secondary hypothyroidism occur?

    <p>As a result of pituitary disease</p> Signup and view all the answers

    What is a potential precipitating factor for myxedema coma? (SATA)

    <p>Exposure to drugs</p> Signup and view all the answers

    Which of the following symptoms may NOT be typically associated with hypothyroidism?

    <p>Increased cardiac output and increased cardiac contractility</p> Signup and view all the answers

    What is a hallmark of myxedema, commonly linked with severe hypothyroidism?

    <p>Puffiness and edema</p> Signup and view all the answers

    Which type of thyroid disorder can lead to a goiter as the body attempts to counteract hormone deficiency?

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

    Which of the following is NOT a clinical manifestation of hypothyroidism?

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

    Which treatment strategy is crucial during a myxedema coma?

    <p>Supporting vital functions</p> Signup and view all the answers

    What is the primary reason for monitoring TSH levels in a patient undergoing treatment for hypothyroidism?

    <p>To determine the effectiveness of thyroid hormone replacement therapy</p> Signup and view all the answers

    Which of the following is an indication of levothyroxine toxicity?

    <p>Tachycardia and palpitations</p> Signup and view all the answers

    Why is free T4 considered more important than free T3 in the assessment of hypothyroidism?

    <p>Free T4 is more reflective of thyroid function and therapy adjustment needs</p> Signup and view all the answers

    What is the recommended dosage adjustment frequency for levothyroxine in patients being treated for hypothyroidism?

    <p>Every 4-6 weeks according to lab reports and adverse effects</p> Signup and view all the answers

    How should levothyroxine be administered to ensure optimal absorption?

    <p>On an empty stomach</p> Signup and view all the answers

    In primary hypothyroidism, what changes can be expected in TSH levels?

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

    Which of the following is a key component in evaluating a patient for hypothyroidism?

    <p>Taking a comprehensive patient history and physical examination</p> Signup and view all the answers

    What is the ultimate goal of pharmacotherapy for hypothyroidism?

    <p>To restore a euthyroid state</p> Signup and view all the answers

    What is the primary function of T3 and T4?

    <p>Increasing metabolic activity and protein synthesis</p> Signup and view all the answers

    Study Notes

    Thyroid Hormones

    • Thyroxine (T4) is the most abundant hormone in the thyroid gland, and it’s converted into tri-iodothyronine (T3).
    • T3 and T4 increase metabolic activity and protein synthesis, influencing processes like body temperature, growth, and development.

    Thyroid Hormone Synthesis

    • Iodine is essential for the synthesis of thyroid hormones.

    Hyperthyroidism

    • Graves’ disease is the most common cause of hyperthyroidism.
    • Thyroid-stimulating immunoglobulins (TSI) in Graves’ disease mimic TSH, stimulating the thyroid gland to produce excessive hormones.
    • Thyrotoxic crisis, a potentially life-threatening complication of hyperthyroidism, can occur if left untreated.

    Hypothyroidism

    • The primary goal of pharmacotherapy for hypothyroidism is to restore euthyroid state (normal thyroid function).
    • Levothyroxine is the most common medication for hypothyroidism. TSH levels should be checked 4-6 weeks after any dose changes to assess efficacy.
    • Myxedema coma, a serious complication of hypothyroidism, can occur if left untreated.

    Hyperthyroidism Treatment

    • **Medications **
      • Antithyroid medications (thionamides)
        • Methimazole (preferred for long-term management)
        • Propylthiouracil (PTU) (used in specific situations like 1st trimester of pregnancy or acute cases)
      • Iodine solutions
      • Beta blockers (reduce palpitations, tremors, anxiety, heat intolerance, and tachycardia)
        • Propranolol (non-selective, targets β1 + β2 receptors)
        • Atenolol (preferred in patients with asthma)
      • Corticosteroids
    • Supportive care
      • Manage hyperthermia, maintain fluid and electrolyte balance, and ensure adequate nutrition.
    • Management of stressor (i.e., treat the underlying cause)

    Hyperthyroidism: Evaluation

    • History and physical assessment
    • Lab values to look out for
      • TSH (thyroid-stimulating hormone) - decreased
        • Negative feedback loop lowers TSH levels but Thyroid-Stimulating Immunoglobulins (TSIs) are unaffected.
      • Free T4 - increased
        • Exceeds protein binding capacities, so free T3/T4 remain unbound and responsible for manifestations.
      • Free T3 - increased
        • Free T3 increases sooner and to a larger extent than T4.
      • Note: Total T3 and T4 levels include bound hormones. Only free hormone is biologically active.

    24-hour Radioactive Iodine Uptake (RAIU)

    • Can be used to differentiate Graves' disease from other forms of thyroiditis.
      • Graves' disease: uptake of 35-90%
      • Thyroiditis: uptake less than 20%
        • Thyroid is inflamed and damaged, reducing its ability to take up iodine.
      • Nodular goiter: high normal range
        • Uptake rate depends on nodule size.
    • Normal result is 3-16% at 6 hours and 8-25% at 24 hours.

    Pharmacotherapy for Hyperthyroidism

    • Overall goals:
      • Block the adverse effects of thyroid hormones.
      • Stop the over-secretion of thyroid hormones.
    • Treatment options:
      • Antithyroid meds (thionamides)
      • Radioactive iodine therapy
      • Subtotal thyroidectomy (surgical)

    Thionamides

    • Inhibit the enzyme thyroid peroxidase (TPO), crucial for the synthesis of thyroid hormones.
    • Used long term or short term.
    • Graves' Disease: Pathophysiology:*
    • Thyroid-Stimulating Immunoglobulins (TSIs) are abnormal antibodies that mimic TSH.
    • TSIs attach to the TSH receptors of the thyroid, gaining control of the pathway.
    • TSIs stimulate the thyroid to release T3/T4.
    • Thyrotoxicosis (excess of thyroid hormones).
    • Thyroid enlargement.
    • Graves' Disease: Clinical Manifestations:*
    • Nervousness, shaking, increased nervousness, irritability.
    • Tremors (especially in hands).
    • Tachycardia, palpitations.
    • Feeling hot.
    • Weight loss.
    • Fatigue, feeling exhausted due to increased metabolic activity.
    • More frequent bowel movements.
    • Shorter or lighter menstrual periods.
    • Goiter - bulge in the neck where the thyroid is.
    • Exophthalmos - bulging eyes.
    • Pretibial myxedema - lumpy rash on the shins.

    Ophthalmopathy

    • Exophthalmos: Excessive accumulation of fluid behind the eyes.
    • The tissue and muscles behind the eyes become inflamed, and edema occurs, pushing the eyeballs forward away from the orbits.
    • If the eyelids are unable to close, the exposed cornea becomes dry and irritated, which could lead to corneal abrasions and corneal ulcers.
    • Usually bilateral, but can be unilateral.

    Pretibial Myxedema

    • Fluid accumulates under the skin (on lower legs) and termed pretibial myxedema.
    • It looks like a lumpy rash on the shins.
    • Can spread to the feet, and can spread to other parts of the body if untreated.

    Hyperthyroidism complication: Thyrotoxic Crisis (aka Thyroid Storm)

    • Acute, rare condition where all of the hyperthyroid manifestations are intensified.
    • Rapid increase in T3 and T4 secretion.
    • The heart and nervous system are more sensitive to catecholamines (epinephrine and norepinephrine).
    • Cause: Stressor such as infection, trauma, surgery in a patient with hyperthyroidism.
    • Thyrotoxic crisis is a medical emergency that requires immediate treatment.

    Thyrotoxic Crisis Manifestations:

    • Severe tachycardia (exceeding 140 bpm)
    • Heart failure (from increased cardiac workload)
    • Shock (unable to keep up with cardiac demand)
    • Hyperthermia (up to 40.7 degrees C)
    • Restlessness and agitation
    • Seizures
    • Abdominal pain, nausea, vomiting, diarrhea
    • Delirium
    • Coma

    Thyrotoxic Crisis: Treatment

    • Decrease the amount of circulating hormones (e.g., prior to thyroid surgery).
    • Improvement usually occurs within 2 weeks, with therapeutic results in 4-8 weeks, and up to 12 weeks to see significant lab result changes.
    • Therapy continues for 6 months to 2 years.
    • Drugs are not curative, patients can go into remissions and exacerbations.

    Thionamides: Adverse Effects

    • Agranulocytosis (severely low levels of white blood cells)
      • Bone marrow suppression and immune response targeting neutrophils and granulocytes.
      • Fever and sore throat may be early indicators.

    Iodine Therapy

    • Can be used in combination with antithyroid drugs.
    • Rapidly inhibits the synthesis of T3 and T4 and blocks their release into circulation.
    • It also decreases the vascularity of the thyroid gland, making surgery safer and easier.
    • Maximum effect is seen within 1-2 weeks, and the therapeutic effect lessens.
    • Signs of toxicity
      • Swelling of buccal mucosa and other mucous membranes
      • Excessive salivation
      • Nausea and vomiting
      • Skin reactions
    • Iodine should be stopped if there is toxicity.

    Radioactive Iodine Therapy (RAI)

    • Treatment of choice for most postpubertal adolescents and young adults.
    • Delayed response.
    • Should not be used in pregnancy or lactation.
    • Avoid in young children.
    • Adverse Effects: Dryness and irritation of the mouth and throat; a high incidence of post-treatment hypothyroidism.

    Subtotal Thyroidectomy

    • Involves removal of the whole lobe, isthmus, and some of the remaining lobe (about ⅘ grams left behind).
    • Indications:
      • Large goiter compressing the trachea (breathing difficulties or positional dyspnea)
      • No response to medications
      • Thyroid cancer
      • Not a candidate for RAI
    • Typically treated with medications prior to surgery to achieve a euthyroid state (state of having normal thyroid gland function) and to manage symptoms.

    Postoperative Management: Assessing for Complications

    • Signs and symptoms of hypothyroidism.
    • Hypocalcemia secondary to damage to the parathyroid glands.
    • Hemorrhage
    • Damage to the laryngeal nerve.
    • Thyrotoxic crisis
    • Infection

    Nutrition (Hyperthyroidism)

    • May need a high-calorie diet.
    • Increased protein allowance
    • GI tract may be hyperactive - avoid high fiber (patients already have diarrhea or go to the bathroom more frequently).
    • May be more sensitive to the effects of caffeine.

    Thyroid Gland

    • Located in the anterior portion of the neck in front of the trachea (butterfly shaped).
    • It consists of 2 encapsulated lobes connected by a narrow isthmus.
    • Highly vascular (for hormone distribution).
    • Regulated by the thyroid-stimulating hormone (TSH), which is secreted by the anterior pituitary gland.
    • Hormones produced from the thyroid gland:
      • Triiodothyronine (T3) - more potent and influences metabolism
      • Thyroxine (T4) - more abundant, but needs to be converted to T3 to have a metabolic effect.
      • Calcitonin (regulates calcium levels but is not as important).

    Triiodothyronine (T3) & Thyroxine (T4)

    • The major function of the thyroid gland is the production, storage, and release of T4 and T3.
    • T4 = most abundant thyroid hormone and accounts for more than 90% of the hormone produced by the thyroid gland.
      • T4 = largely inactive and is converted into the more active T3 in the kidneys and liver.
    • T3 = most powerful - most potent of thyroid hormones.
    • Iodine is necessary for the thyroid gland to synthesize thyroid hormones.

    Effects of T3 & T4 on the body:

    • Metabolic rate
    • Caloric requirements
    • Oxygen consumption
    • Carbohydrate and lipid metabolism
    • Growth and development
    • Brain function
    • Nervous system activity

    TRH→ TSH→ T4/T3 thyroid hormones

    • Regulated by a negative feedback loop.
    • Once T3/T4 reach a certain level, they will inhibit the release of TRH and TSH.

    Hyperthyroidism

    • A sustained increase in the synthesis and release of thyroid hormones by the thyroid gland.
      • The most common cause is Graves' disease.
      • Other causes include toxic nodular goiter, thyroiditis, pituitary tumors, and thyroid cancer.

    Toxic Nodular Goiter (Plummer's Disease)

    • Characterized by nodules that secrete thyroid hormones.
    • The term "toxic" refers to the overproduction of thyroid hormones, leading to hyperthyroidism.
    • Causes: environmental, genetic, or chronic iodine deficiency (patients get more nodules because they are trying to capture more iodine from the bloodstream, leading to thyroid or more overproduction).

    Thyrotoxicosis

    • Thyrotoxicosis is the clinical state that results from increased levels of T3, T4, or both.
      • Can be an acute or sustained increase.
    • Hyperthyroidism and thyrotoxicosis usually occur together.
    • Thyrotoxicosis manifestations may include:
      • Anxiety
      • Tachycardia; arrhythmias
      • Weight loss; increased appetite
      • Heat intolerance; excessive sweating
      • Tremors
    • Symptoms can vary in severity and duration.
    • Manifestations will depend on the underlying cause.

    Graves' Disease

    • An autoimmune disease of unknown cause where the thyroid gland is enlarged, and thyroid hormones (T3/T4) are secreted and released in increased amounts.
    • Accounts for 90% of cases of hyperthyroidism.
    • Graves' disease is characterized by remissions and exacerbations, even when treated.
    • Graves' disease (overstimulation of the thyroid) may lead to destruction of the thyroid tissue, which can cause hypothyroidism.

    Hypothyroidism

    • Occurs due to a decrease in thyroid hormone production
    • Can be primary or secondary
      • Primary: Thyroid gland dysfunction
      • Secondary: Pituitary or hypothalamus dysfunction

    Causes of Hypothyroidism

    • Iodine deficiency is the most common cause globally, primarily affecting thyroid production
    • Hashimoto's thyroiditis is the most common cause in Canada, an autoimmune condition that destroys the thyroid
      • Atrophy: Can be caused by hyperthyroidism treatments like surgery or radioactive iodine therapy

    Clinical Manifestations of Hypothyroidism

    • Can develop suddenly (thyroidectomy) or gradually over time
    • Typically presents with fatigue and lethargy
    • Impact on cardiac function: decreased output and contractility
    • Personality changes, slowed speech, reduced drive and motivation
    • Goiter: Enlarged thyroid as the body tries to stimulate hormone production
    • Other symptoms include anemia, dyslipidemia, decreased GI motility, menorrhagia, cold intolerance, hair loss, dry skin, brittle nails, hoarseness, muscle weakness, and weight gain

    Myxedema

    • Prolonged hypothyroidism can lead to this condition
    • An accumulation of mucopolysaccharides in the dermis and tissues causes mucinous edema
    • Presents with puffiness, periorbital edema, and a mask-like appearance

    Myxedema Coma

    • A rare but life-threatening complication of hypothyroidism
    • Progression from sluggishness and drowsiness to decreased consciousness and coma
    • Precipitated by infection, trauma, drugs, or exposure to drugs
    • Characterized by low temperature, hypotension, and hypoventilation
    • Requires urgent treatment: addressing underlying causes, supporting vital functions, IV thyroid hormone replacement, and supportive care

    Hypothyroidism Evaluation

    • History and physical exam
    • TSH: Increased in primary hypothyroidism, may be decreased in secondary hypothyroidism
    • Free T4: Decreased, more important than fT3 for assessment and management
    • Free T3: Decreased

    Pharmacotherapy for Hypothyroidism

    • Goal is to restore euthyroid state
    • Levothyroxine (Synthroid): synthetic T4
      • Usually started at a lower dose and increased slowly every 4-6 weeks
      • Monitor for cardiac side effects (chest pain, arrhythmias)
    • Administration: Taken on an empty stomach for optimal absorption
    • Lifelong treatment
    • TSH levels are checked 4-6 weeks after dose adjustments
    • Levothyroxine toxicity: Orthopnea, dyspnea, tachycardia, palpitations, insomnia
    • Management during pregnancy: Increased metabolic needs, particularly during the first trimester

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    Description

    This quiz covers essential knowledge about thyroid hormones, including the roles of T3 and T4, the synthesis of these hormones, and conditions such as hyperthyroidism and hypothyroidism. Test your understanding of related treatments and medical implications.

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