Endocrinology Exam Questions and Answers

Correct Answer: A

Rationale: Congenital adrenal hyperplasia does not lead to dwarfism. It is a group of genetic disorders that affect the adrenal glands and can cause various symptoms related to hormone imbalances. In contrast, the other conditions listed - hypopituitarism, homocystinuria, and pseudohypoparathyroidism - can all lead to dwarfism through different mechanisms. Hypopituitarism is characterized by a deficiency of pituitary hormones, including growth hormone, which can result in stunted growth and dwarfism. Homocystinuria is a metabolic disorder that can affect bone growth and lead to skeletal abnormalities resulting in dwarfism. Pseudohypoparathyroidism is a rare genetic disorder that can manifest with short stature or dwarfism due to skeletal abnormalities caused by altered bone metabolism.

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: C

Rationale: Cushing's syndrome is a collection of signs and symptoms caused by prolonged exposure to high levels of cortisol. Common features of Cushing's syndrome include weight gain, central obesity, moon face, buffalo hump, easy bruising, muscle weakness, and menstrual irregularities in women.

Correct Answer: A

Rationale: Graves' disease is an autoimmune disorder where autoantibodies, known as thyroid-stimulating immunoglobulins (TSIs) or thyroid-stimulating antibodies (TSAs), bind to and stimulate the thyroid-stimulating hormone (TSH) receptors on thyroid follicular cells. This leads to increased production and secretion of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine), causing hyperthyroidism. The autoantibodies essentially mimic the action of TSH, resulting in excess thyroid hormone release and manifestation of hyperthyroid symptoms. This underlying pathology of Graves' disease is distinct from other causes of hyperthyroidism, making choice A the correct statement.

Correct Answer: D

Rationale: Hypoglycemia is characterized by a low blood sugar level, which can lead to various symptoms. The features of hypoglycemia typically include drenching sweat, tachycardia (increased heart rate), and tachypnea (rapid breathing). A brisk jerk, on the other hand, is not a typical feature of hypoglycemia. Symptoms such as confusion, dizziness, shakiness, hunger, weakness, and irritability are more commonly associated with hypoglycemia than a brisk jerk.