Endocrinology Exam Questions and Answers

Correct Answer: A

Rationale: Hypertonicity (increased osmolarity or high concentration of solutes in the blood) is the most potent stimulus for the hypothalamic production of arginine vasopressin (also known as antidiuretic hormone or ADH). When the body senses increased plasma osmolality, the osmoreceptors in the hypothalamus stimulate the release of vasopressin from the posterior pituitary gland. Vasopressin acts on the kidneys to increase water reabsorption and decrease urine output, helping to restore normal osmolarity. This mechanism helps to conserve water and maintain body fluid balance in response to dehydration or increased solute concentration in the blood.

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.

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: B

Rationale: Cushing's syndrome is a disorder caused by prolonged exposure to high levels of cortisol hormone. While Cushing's syndrome can manifest with a variety of symptoms, peripheral neuropathy is not a typical feature of this condition. Cushing's syndrome is commonly associated with symptoms such as hirsutism (excessive hair growth), purple striae (skin stretch marks that are purple in color), and acne due to the hormonal imbalances it creates. Peripheral neuropathy, which involves damage to the peripheral nerves leading to symptoms like numbness, tingling, and weakness in the extremities, is not a characteristic symptom of Cushing's syndrome.

Correct Answer: D

Rationale: Neurogenic diabetes insipidus is due to a deficiency in vasopressin (antidiuretic hormone, ADH) production in the hypothalamus or a failure of proper vasopressin release from the posterior pituitary. Causes of neurogenic DI typically involve factors affecting vasopressin synthesis, storage, or release. However, mutations in the vasopressin gene itself would be a cause of genetic forms of diabetes insipidus, not neurogenic diabetes insipidus. Common causes of neurogenic diabetes insipidus include traumatic brain injury, brain tumors, pituitary adenomas, meningitis, and Sheehan's syndrome.