Endocrinology Exam Questions and Answers

Correct Answer: D

Rationale: The overnight 1-mg dexamethasone suppression test is commonly used as an initial screening test for Cushing's syndrome. In this test, a patient takes 1 mg of dexamethasone orally at 11 p.m., and their serum cortisol level is measured the next morning. In patients with Cushing's syndrome, the cortisol levels will not be suppressed by the dexamethasone due to the presence of excessive cortisol production.

Correct Answer: B

Rationale: ADH (antidiuretic hormone), also known as vasopressin, is secreted by the posterior lobe of the pituitary gland. ADH plays a key role in regulating water balance in the body by controlling the reabsorption of water in the kidneys. When the body senses a decrease in blood volume or an increase in blood osmolarity, ADH is released to signal the kidneys to conserve water, leading to concentrated urine production and water retention in the body.

Correct Answer: D

Rationale: An Addisonian crisis, also known as an acute adrenal crisis, is a life-threatening medical emergency that occurs due to severe adrenal insufficiency, leading to a sudden drop in cortisol levels. Cortisol is a vital hormone produced by the adrenal glands, and its deficiency can result in serious symptoms such as hypotension, dehydration, electrolyte imbalances, and shock. If left untreated, an Addisonian crisis can be fatal. Therefore, the correct description of an Addisonian crisis is severe adrenal insufficiency resulting in dangerously low serum cortisol levels.

Correct Answer: D

Rationale: The renin-angiotensin-aldosterone axis does not involve the hypothalamus or pituitary gland; instead, it primarily involves the kidneys and the renin-secreting cells. In this axis, renin is released in response to low blood pressure, leading to the formation of angiotensin II and the subsequent release of aldosterone from the adrenal glands. Feedback mechanisms for this axis primarily involve the regulation of renin release based on blood pressure rather than involving direct negative feedback from downstream hormones on the hypothalamus or pituitary gland. On the other hand, choices A, B, and C all involve classic examples of hypothalamic-pituitary negative feedback loops where the end hormone suppresses the release of the stimulating hormones at the hypothalamic and pituitary levels.

Correct Answer: D

Rationale: Weight gain is a common symptom of Cushing's syndrome due to the excessive production of cortisol, a hormone that regulates metabolism and fat storage. The other symptoms listed, such as easy bruising, acne, and stretch marks, are also characteristic features of Cushing's syndrome. However, weight loss is typically not associated with this condition. In fact, individuals with Cushing's syndrome often experience unexplained and rapid weight gain, especially in the face, abdomen, and upper back (resulting in a characteristic "buffalo hump" appearance), rather than weight loss.