Endocrine Regulation Quiz
52 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

How does PTH affect calcium levels in the body?

PTH activates osteoclasts to resorb bone, increases calcium reabsorption from urine, and promotes renal activation of vitamin D for enhanced gut absorption of calcium.

What role does calcitonin play in the body, especially regarding medullary thyroid cancer?

Calcitonin, produced by parafollicular C cells, helps lower serum calcium levels and serves as a marker for the recurrence of medullary thyroid cancer.

Describe the relationship between TSH levels and thyroid hormone levels in the body.

TSH levels are suppressed when thyroid hormone levels are high and stimulated when thyroid hormone levels are low, demonstrating a negative feedback mechanism.

What are the characteristics that distinguish a simple goitre from isolated and dominant swellings in the thyroid?

<p>A simple goitre is a general enlargement of the thyroid gland, while isolated swelling refers to a discrete nodule in one lobe, and dominant swelling indicates discrete swellings with abnormalities in other gland areas.</p> Signup and view all the answers

What are the stages in the natural history of simple goitre formation?

<p>The stages include persistent growth stimulation leading to diffuse hyperplasia, where all lobules consist of active follicles with uniform iodine uptake.</p> Signup and view all the answers

Explain the transition from a diffuse hyperplastic goitre to a nodular goitre.

<p>The transition occurs through fluctuating stimulation, leading to active lobules becoming hyperplastic and vascular until necrosis occurs, forming nodules filled with inactive follicles or colloid.</p> Signup and view all the answers

What is the significance of palpability and smoothness in diagnosing a goitre?

<p>Palpable and smooth nodules suggest a benign goitre, while irregularity and hardness may raise suspicions of carcinoma.</p> Signup and view all the answers

What role does ultrasound play in the investigation of a goitre?

<p>Ultrasound is the gold standard for assessing goitre, helping to identify characteristics that determine if further investigations like FNAC are necessary.</p> Signup and view all the answers

In what situations should FNAC be performed in the context of a goitre?

<p>FNAC should be performed on any nodule within the goitre that exhibits concerning ultrasonic features to assess for malignancy.</p> Signup and view all the answers

Describe the complications associated with a goitre, specifically regarding tracheal obstruction.

<p>Tracheal obstruction can occur due to significant lateral displacement or compression from the retrosternal extension of the goitre.</p> Signup and view all the answers

How can the incidence of goitre be reduced in endemic areas, and what initial treatment options exist?

<p>The introduction of iodised salt has significantly reduced goitre incidence, while thyroxine treatment in early hyperplastic stages may induce regression.</p> Signup and view all the answers

What differentiates transient episodes of mild hyperthyroidism in goitre patients from secondary thyrotoxicosis?

<p>Transient episodes of mild hyperthyroidism are common in up to 30% of patients with goitre, while secondary thyrotoxicosis indicates a more serious and sustained condition.</p> Signup and view all the answers

What percentage of isolated thyroid swellings is found to be malignant?

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

What surgical procedure is commonly recommended for managing multinodular goitre with significant symptoms?

<p>Total thyroidectomy.</p> Signup and view all the answers

What are the key criteria used to distinguish between benign follicular adenoma and follicular carcinoma?

<p>Histological criteria, including capsular and vascular invasion.</p> Signup and view all the answers

Name a symptom that may indicate the need for surgery in patients with nodular goitre.

<p>Tracheal compression.</p> Signup and view all the answers

In the case of toxic adenoma or toxic multinodular goitre, what diagnostic test is indicated to locate hyperfunctioning areas?

<p>Isotope scanning.</p> Signup and view all the answers

What is the importance of using ultrasound guidance during fine-needle aspiration cytology (FNAC) for thyroid swellings?

<p>It enhances the reliability and precision of biopsy sampling.</p> Signup and view all the answers

What percentage of benign multinodular goitre cases might see regression in size over 10 years?

<p>More than 50%.</p> Signup and view all the answers

What ultrasound features in a thyroid swelling could indicate malignancy?

<p>Microcalcification and increased vascularity.</p> Signup and view all the answers

What is a potential consequence of leaving too much thyroid tissue after subtotal thyroidectomy?

<p>Residual thyroid tissue may cause recurrent goitre.</p> Signup and view all the answers

What is the general gender prevalence for multinodular goitre?

<p>Three to four times more frequent in women than men.</p> Signup and view all the answers

What is the primary advantage of surgical intervention for toxic goitre compared to radioiodine treatment?

<p>The primary advantage is that surgery provides a rapid cure by effectively removing the overactive thyroid tissue.</p> Signup and view all the answers

List two significant disadvantages associated with subtotal thyroidectomy.

<p>Two significant disadvantages are the risk of permanent hypoparathyroidism and nerve injury.</p> Signup and view all the answers

Why might young women experience poorer cosmetic results after surgery for toxic goitre?

<p>Young women may experience poorer cosmetic results due to the noticeable surgical scar that remains after thyroidectomy.</p> Signup and view all the answers

What factors should be considered when choosing between surgical and radioiodine treatment for toxic goitre?

<p>Factors include the patient's age, overall health, personal preferences, and available medical facilities.</p> Signup and view all the answers

What condition can arise in at least 5% of cases following subtotal thyroidectomy?

<p>Recurrence of thyrotoxicosis can occur in at least 5% of cases following subtotal thyroidectomy.</p> Signup and view all the answers

A large goitre is often treated with ______ because it does not respond well to other treatments.

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

Propranolol is a ______ blocking drug that can help manage symptoms before surgery.

<p>beta-adrenergic</p> Signup and view all the answers

The goal of preoperative preparation is to make the patient ______ at the time of operation.

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

After surgery, it is important to continue beta-blocker treatment for ______ days.

<p>7</p> Signup and view all the answers

Carbimazole is often used for preoperative preparation at a dose of ______ mg per day.

<p>30–40</p> Signup and view all the answers

Iodine is typically given with carbimazole or a beta-blocker for up to ______ days prior to surgery.

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

Failure to control hyperthyroidism may require ______ admission for the patient.

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

Symptomatic and supportive treatment for dehydration requires the administration of intravenous ______.

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

Propranolol can be administered intravenously or orally to block ______ effects.

<p>β-adrenergic</p> Signup and view all the answers

Cellulitis may require the prescription of ______.

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

Intradermal injections of corticosteroid are indicated for ______ or keloid scars.

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

A stitch granuloma may occur with or without sinus formation after the use of non-______ suture material.

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

A significant subcutaneous abscess is exceptionally rare and should be ______.

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

The distinction between follicular carcinoma and an adenoma can only be made by ______ examination.

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

Thyroid lymphoma is considered to be a primary thyroid ______.

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

Diagnosis and treatment of benign tumours often involve a procedure called ______.

<p>total lobectomy</p> Signup and view all the answers

Patient should be considered for surgery if there is significant __________ compression.

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

Graves' disease is a common cause of __________ due to excessive thyroid hormone levels.

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

The symptoms of thyrotoxicosis include tiredness, emotional lability, and __________ intolerance.

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

Tachycardia and exophthalmos are signs often associated with __________.

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

Antithyroid drugs like carbimazole aim to restore the patient to a __________ state.

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

Surgery and __________ are specific measures used in the treatment of thyrotoxicosis.

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

A solitary overactive nodule that may not respond to TSH is referred to as a __________ nodule.

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

Postoperative complications can include laryngeal nerve __________.

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

The duration of treatment for hyperthyroidism may vary, with milder cases treated for approximately __________ months.

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

Study Notes

Parathyroid Hormone (PTH)

  • PTH is secreted by the parathyroid glands and is the main regulator of calcium homeostasis.
  • PTH increases blood calcium levels by stimulating osteoclasts to resorb bone.
  • PTH increases calcium reabsorption in the kidneys, leading to less calcium being excreted in urine.
  • PTH increases renal activation of vitamin D, enhancing calcium absorption in the gut.
  • PTH increases phosphate excretion by the kidneys.

Calcitonin

  • Calcitonin is produced by parafollicular C cells of the thyroid gland.
  • C cells are of neuroendocrine origin and migrate to the thyroid from the ultimobranchial body.
  • Calcitonin is a serum marker for medullary thyroid cancer recurrence.
  • Calcitonin lowers blood calcium levels by inhibiting osteoclast activity.

Pituitary-Thyroid Axis

  • The pituitary-thyroid axis controls the synthesis and release of thyroid hormones.
  • Thyroid-stimulating hormone (TSH) is secreted by the anterior pituitary gland.
  • TSH secretion is regulated by negative feedback, with high levels of circulating thyroid hormones suppressing TSH production and low levels stimulating TSH production.
  • Thyrotropin-releasing hormone (TRH) from the hypothalamus also stimulates TSH secretion.

Thyroid-Stimulating Antibodies (TSH-RAbs)

  • TSH-RAbs are antibodies that bind to TSH receptors on follicular cell membranes.
  • TSH-RAbs activate TSH receptors, mimicking the actions of TSH.
  • TSH-RAbs have a longer duration of action than TSH.
  • TSH-RAbs are responsible for most cases of thyrotoxicosis that aren't due to autonomous toxic nodules.

Thyroid Enlargement

  • A normal thyroid gland is not palpable.
  • Goitre refers to a generalized enlargement of the thyroid gland.
  • An isolated thyroid swelling is a discrete nodule in one lobe.
  • Dominant swelling is a discrete nodule with evidence of other abnormalities in the gland.

Simple Goitre

  • Simple goitre is an enlargement of the thyroid gland without any functional changes.
  • Etiology of simple goitre includes:
    • Stimulation of the thyroid gland by TSH.
    • Inappropriate secretion from a pituitary microadenoma (rare).
    • Chronically low levels of circulating thyroid hormones.
    • Dietary deficiency of iodine.
    • Defective hormone synthesis.

Natural History of Simple Goitre

  • The natural history of simple goitre progresses in stages:
    • Diffuse hyperplastic goitre: Active thyroid follicles, uniform iodine uptake, reversible if stimulation ceases.
    • Mixed pattern goitre: Areas of active and inactive follicles.
    • Hemorrhage and necrosis: Active lobules become vascular, leading to haemorrhage and necrosis.
    • Nodular goitre: Necrotic lobules coalesce, resulting in nodules filled with colloid or inactive follicles.
    • Multinodular goitre: Most nodules are inactive, with active follicles only in the internodular tissue.

Multinodular Goitre

  • Multinodular goitre is characterized by multiple nodules within the thyroid gland.
  • It is more common in women and occurs in 3-4% of the adult population.
  • Around 30% of thyroid swellings are dominant, with evidence of abnormalities in other areas of the gland.
  • The risk of malignancy associated with discrete thyroid swellings is higher than other thyroid swellings.
  • 15% of isolated swellings are malignant, and an additional 30-40% are follicular adenomas.
  • FNAC is helpful in identifying papillary thyroid cancer but cannot distinguish between benign follicular adenoma and follicular carcinoma.

Toxic Nodular Goitre

  • Toxic nodular goitre is characterized by hyperthyroidism and nodular thyroid enlargement.
  • It is often large, uncomfortable, and may enlarge further with antithyroid drugs.
  • A large goitre should be treated surgically due to poor response to radioiodine or antithyroid drugs.

Toxic Nodule

  • Toxic nodule is a single nodule in the thyroid gland that is hyperfunctioning and causing hyperthyroidism.
  • Surgery or radioiodine is appropriate treatment.

Graves' Disease

  • Graves' disease is the most common cause of hyperthyroidism, characterized by diffuse thyroid enlargement and hyperthyroidism.
  • It is an autoimmune disease where antibodies stimulate TSH receptors.
  • Treatment options include:
    • Antithyroid drugs: Carbimazole or propylthiouracil.
    • Radioiodine ablation.
    • Surgery: Total or subtotal thyroidectomy.

Management of Thyrotoxicosis

  • Before surgery:
    • Patients are prepared to be biochemically euthyroid.
    • This is achieved with antithyroid drugs like carbimazole.
    • β-adrenergic blocking drugs can be used to reduce symptoms.
    • Iodides can be given before surgery to reduce vascularity.
    • Surgery aims to reduce the mass of functioning thyroid tissue.
    • Risks include:
      • Recurrence of thyrotoxicosis.
      • Permanent hypoparathyroidism.
      • Nerve injury.

Radioiodine Therapy

  • Radioiodine destroys thyroid cells, reducing the mass of functioning tissue.
  • Advantages: No surgery, no prolonged drug therapy.
  • Disadvantages: Requires isotope facilities, quarantine, pregnancy considerations, eye signs may be aggravated.

Treatment Choice for Thyrotoxicosis

  • Treatment choice depends on individual factors, such as age, goitre size, presence of eye signs, patient preference, and availability of facilities.
  • In endemic areas, iodine deficiency can lead to goitre, and treatment with iodized salt has significantly reduced its incidence.
  • Long-term follow-up is essential after radioiodine or subtotal thyroidectomy.

Large Goitre Treatment

  • Surgical treatment is preferred for large goitres because they respond poorly to radioiodine and antithyroid drugs.

Toxic Nodule Treatment

  • Surgery or radioiodine therapy is suitable for toxic nodules.
  • For patients over 45, radioiodine is a recommended alternative due to reduced risk of delayed thyroid insufficiency.

Failure of Previous Treatment

  • Surgery or radioactive iodine (123I) ablation are suitable treatment options if prior antithyroid drugs or radioiodine fail.

Surgery for Thyrotoxicosis: Preoperative Preparation

  • The goal is to achieve a euthyroid state prior to surgery.
  • Preparation typically occurs as an outpatient, hospital admission is rare unless severe symptoms, uncontrolled hyperthyroidism, or non-compliance with medication.
  • Carbimazole (30-40 mg/day) is the preferred drug for preparation.
  • Once euthyroid (8-12 weeks), carbimazole dosage can be reduced to 5 mg 8-hourly or a 'block and replace' regimen can be implemented.
  • Iodides should not be used alone as more effective drugs are available for preoperative treatment.
  • Alternative methods of preparation include using β-adrenergic blocking drugs to abolish clinical manifestations of thyrotoxicosis.

β-Adrenergic Blocker Treatment

  • Preferred drugs include Propranolol (40 mg t.d.s) or Nadolol (160 mg daily).
  • β-blockade provides rapid clinical response, rendering patients clinically euthyroid within days rather than weeks.
  • β-blockers do not interfere with thyroid hormone synthesis, thus hormone levels remain high during treatment and after thyroidectomy.
  • Continued β-blocker treatment for 7 days postoperatively is crucial.

Indications for Surgery

  • Consider surgery for patients with significant airway compression.

Hyperthyroidism

  • Thyrotoxicosis: symptoms caused by elevated thyroid hormone levels.
  • Clinical types:
    • Diffuse toxic goitre (Graves' disease)
    • Toxic nodular goitre
    • Toxic nodule
    • Hyperthyroidism due to rarer causes

Clinical Features of Thyrotoxicosis

  • Symptoms:
    • Tiredness
    • Emotional lability
    • Heat intolerance
    • Weight loss
    • Excessive appetite
    • Palpitations
  • Signs:
    • Tachycardia
    • Hot, moist palms
    • Exophthalmos
    • Eyelid lag/retraction
    • Agitation
    • Thyroid goitre and bruit

Diffuse Toxic Goitre (Graves' Disease)

  • Characterized by a diffuse vascular goitre appearing concurrently with hyperthyroidism.
  • Usually affects younger women.
  • Frequently associated with eye signs.
  • Represents primary thyrotoxicosis.
  • 50% of patients have a family history of autoimmune endocrine diseases.

Toxic Nodular Goitre

  • Simple nodular goitre present for an extended period before hyperthyroidism develops.
  • Commonly occurs in middle-aged or elderly individuals.
  • Rarely associated with eye signs.
  • Represents secondary thyrotoxicosis.

Toxic Nodule

  • Solitary, overactive nodule, possibly part of generalized nodularity or a true toxic adenoma.
  • Autonomous, hypertrophy, and hyperplasia are not due to TSH-RAb.
  • TSH secretion is suppressed due to elevated circulating thyroid hormones.
  • Normal thyroid tissue surrounding the nodule remains suppressed and inactive.

Principles of Treating Thyrotoxicosis

  • Non-specific measures: Rest and sedation
  • Specific measures:
    • Antithyroid drugs
    • Surgery
    • Radioiodine

Antithyroid Drugs

  • Commonly used drugs: Carbimazole and propylthiouracil.
  • Goal: Restore euthyroid state and maintain it over a prolonged period, hoping for a permanent remission.

Advantages of Antithyroid Drugs

  • No surgery required.
  • No radioactive materials used.

Disadvantages of Antithyroid Drugs

  • Long-term treatment required.
  • Significant failure rate (at least 50%).

Antithyroid Drug Treatment Duration

  • Treatment duration depends on toxicity severity:
    • Milder cases: 6 months
    • Severe cases: 2 years

Thyrotoxicosis Treatment: Symptomatic and Supportive Care

  • For dehydration, hyperpyrexia, and restlessness:
    • Intravenous fluids
    • Cooling with ice packs
    • Oxygen administration
    • Diuretics for cardiac failure
    • Digoxin for uncontrolled atrial fibrillation
    • Sedation
    • Intravenous hydrocortisone

Thyrotoxicosis Treatment: Specific Therapy

  • Carbimazole: 10-20 mg 6-hourly
  • Lugol's iodine: 10 drops 8-hourly orally
  • Sodium iodide: 1g intravenously
  • Propranolol: 1-2 mg intravenously or 40 mg 6-hourly orally to block β-adrenergic effects.

Surgical Complications

  • 1. Hemorrhage:
    • Usually occurs in the first 24 hours after surgery.
    • May require re-exploration.
  • 2. Respiratory distress:
    • Typically occurs due to a hematoma that can obstruct the airway.
    • May require urgent tracheostomy.
  • 3. Recurrent laryngeal nerve injury:
    • Risk of permanent vocal cord paralysis.
    • Caused by inadvertent damage to the nerve during surgery.
  • 4. Hypoparathyroidism:
    • Potential complication of total thyroidectomy or extensive subtotal thyroidectomy.
    • Damage to the parathyroid gland can lead to low calcium levels.
  • 5. Wound healing problems:
    • Common issues:
      • Serous discharge
      • Superficial infection
      • Delayed wound healing
  • 6. Wound Infection:
    • Cellulitis requiring prescription antibiotics is a possibility.
    • Significant subcutaneous or deep cervical abscess is extremely rare and should be drained.
  • 7. Hypertrophic or keloid scar:
    • More likely to form if the incision is over the sternum or in dark-skinned individuals.
    • Intradermal injections of corticosteroid should be given promptly and repeated monthly if necessary.
    • Scar revision rarely provides significant long-term improvement.
  • 8. Stitch granuloma:
    • May occur with or without sinus formation, particularly after using non-absorbable suture material (silk).
    • Absorbable ligatures and sutures should be used during thyroid surgery.
    • Some surgeons use a subcuticular absorbable skin suture instead of skin clips or staples.

Thyroid Neoplasms: Classification

  • Benign Tumors:
    • Follicular adenomas: Present as clinically solitary nodules.
    • Differentiating between follicular carcinoma and adenoma is only possible through histological examination.
    • FNA cannot distinguish between benign and malignant follicular lesions.
    • Treatment: Wide excision (total lobectomy).
    • Prolonged follow-up is unnecessary due to normal remaining thyroid tissue.
  • Malignant Tumors:
    • Majority of primary malignancies are carcinomas derived from follicular cells.
    • Previously categorized as differentiated (papillary, follicular, and Hürthle cell) and undifferentiated (anaplastic).
    • Parafollicular C cells can develop into medullary carcinoma.
    • Thyroid lymphoma is another primary thyroid malignancy.

Thyroid Surgery

  • For diffuse toxic goitre and toxic nodular goitre with overactive internodular tissue, surgery aims to reduce the mass of overactive tissue below a critical level.

Advantages of Thyroid Surgery

  • Removal of the goitre.
  • Rapid cure.
  • High cure rate with adequate surgery.

Disadvantages of Thyroid Surgery

  • Recurrence of thyrotoxicosis (at least 5% with subtotal thyroidectomy).
  • Risk of permanent hypoparathyroidism and nerve injury.
  • Young women may experience poorer cosmetic results from scarring.

Surgical Mortality and Morbidity

  • Risk associated with any surgery, however, with careful preparation and experienced surgeons, mortality is negligible and morbidity is low.

Surgical Options for Graves’ Disease: A Comparison

Radioiodine for Thyrotoxicosis

  • Radioiodine destroys thyroid cells, similar to thyroidectomy, reducing functioning thyroid tissue below a critical level.

Advantages of Radioiodine

  • No need for surgery.
  • Avoids prolonged drug therapy.

Disadvantages of Radioiodine

  • Requires access to isotope facilities.
  • Patient must be quarantined during periods of high radiation levels.
  • Avoid pregnancy and close physical contact (especially with children).
  • May worsen eye signs.

Therapy Choice for Thyrotoxicosis

  • Individualized approach to treatment.
  • Factors to consider when selecting treatment:
    • Age
    • Facility availability
    • Patient personality and wishes
    • Work or family commitments
    • Other coexisting medical or surgical conditions
    • Access to post-treatment care
    • Availability of replacement thyroxine (important in resource-poor countries).
  • Compliance is a key factor influenced by social and intellectual factors.
  • Indefinite follow-up is essential after radioiodine or subtotal thyroidectomy.

Treatment Considerations :

  • Diffuse Toxic Goitre (Graves' Disease):
    • Initial treatment with antithyroid drugs, followed by radioiodine for relapse.
    • Exceptions:
      • Patients refusing radiation.
      • Patients with large goitres.
      • Patients with progressive eye signs.
      • Pregnant patients.
  • Toxic Nodular Goitre:
    • Often large and uncomfortable, potentially enlarging further with antithyroid drugs.
    • Surgery is a suitable option.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Thyroid Gland PDF

Description

Test your knowledge on Parathyroid Hormone (PTH), Calcitonin, and the Pituitary-Thyroid Axis. This quiz covers the roles of these hormones in calcium homeostasis and their regulation. Perfect for students studying endocrinology or related fields.

More Like This

Calcitonin
8 questions

Calcitonin

DeservingKindness avatar
DeservingKindness
Parathyroid Hormone and Calcium Regulation Quiz
25 questions

Parathyroid Hormone and Calcium Regulation Quiz

PortablePeninsula avatar
PortablePeninsula
Parathyroid Gland and Hormones Quiz
20 questions

Parathyroid Gland and Hormones Quiz

ModernComposite avatar
ModernComposite
Thyroid and Parathyroid Functions
10 questions

Thyroid and Parathyroid Functions

BeneficentKremlin avatar
BeneficentKremlin
Use Quizgecko on...
Browser
Open
Browser
Browser