Endocrinology Practice Questions

Correct Answer: B

Rationale: The correct answer is B: Inhibition of the function of thyroid peroxidase. Propylthiouracil inhibits thyroid peroxidase, an enzyme essential for thyroid hormone synthesis. By blocking this enzyme, propylthiouracil reduces the production of thyroid hormones, helping to manage hyperthyroidism in Graves' disease. Explanation: 1. Propylthiouracil directly inhibits thyroid peroxidase, unlike other antithyroid medications that target different mechanisms. 2. Inhibition of thyroid peroxidase leads to decreased synthesis of thyroid hormones, effectively controlling hyperthyroidism. 3. Other choices are incorrect because propylthiouracil does not primarily affect the production of thyroid-stimulating immunoglobulins (choice A), peripheral conversion of T4 to T3 (choice C), or iodine organification (choice D) in the treatment of Graves' disease. In summary, the inhibition of thyroid peroxidase by

Correct Answer: B

Rationale: The correct answer is B: Cretinism. Cretinism is the most common cause of preventable mental deficiency worldwide due to severe iodine deficiency during pregnancy. Iodine is crucial for thyroid hormone production, which is essential for fetal brain development. Beriberi disease (A) is caused by thiamine deficiency and affects the nervous system, not mental deficiency. Folate deficiency (C) can cause neural tube defects but not mental deficiency. Vitamin A deficiency (D) can lead to blindness and immune system issues, but not the most common cause of preventable mental deficiency.

Correct Answer: C

Rationale: The correct answer is C: Stress. Stress triggers the release of growth hormone through the activation of the hypothalamic-pituitary-adrenal axis. When the body is under stress, the hypothalamus signals the pituitary gland to release growth hormone. This hormone then stimulates growth and cell reproduction. Glucocorticoids (A) and somatostatin (B) actually inhibit the release of growth hormone. Obesity (D) can lead to decreased growth hormone release due to disrupted hormonal regulation. In summary, stress is the correct answer as it directly stimulates the release of growth hormone, while the other choices inhibit or have a negative impact on growth hormone release.

Correct Answer: C

Rationale: The correct answer is C: SIADH. Secondary hyperaldosteronism is characterized by increased aldosterone production due to factors outside of the adrenal glands, such as increased renin-angiotensin-aldosterone system activation. SIADH does not involve aldosterone, but rather involves inappropriate secretion of antidiuretic hormone leading to hyponatremia. In contrast, congestive cardiac failure, nephrotic syndrome, and cirrhosis of the liver can all lead to secondary hyperaldosteronism due to mechanisms such as decreased effective circulating volume, renal hypoperfusion, and increased angiotensin II levels, respectively.

Correct Answer: C

Rationale: The correct answer is C: Myxoedema. Myxoedema is associated with hypothyroidism, not SIADH. Guillain-Barre syndrome, subacute bacterial endocarditis, and bronchogenic carcinoma are all conditions that can lead to SIADH due to various mechanisms. Guillain-Barre syndrome can cause SIADH through autonomic dysfunction, endocarditis through the release of inflammatory cytokines, and bronchogenic carcinoma through production of ectopic ADH. Therefore, myxoedema is the only incorrect choice as it does not typically lead to SIADH.