Endocrinology Exam Questions

Correct Answer: A

Rationale: Phaeochromocytoma may be associated with Medullary carcinoma of thyroid, Hyperparathyroidism, and Addison's disease as part of MEN Syndrome (Multiple Endocrine Neoplasia) Type 2. However, it is not typically associated with Neurofibromatosis. Neurofibromatosis is associated with the development of benign tumors of nerve tissue and is not directly linked to the presence of Phaeochromocytoma.

Correct Answer: B

Rationale: Nephrogenic diabetes insipidus (NDI) is a condition where the kidneys are unable to respond to antidiuretic hormone (ADH) as they should, leading to excessive urination and extreme thirst. One of the main causes of nephrogenic diabetes insipidus is the use of certain medications, with lithium being the most common culprit. Lithium can interfere with the kidney's response to ADH, resulting in decreased water reabsorption and the characteristic symptoms of diabetes insipidus. Other causes of NDI can include genetic mutations affecting the vasopressin receptor gene or other underlying conditions such as hypercalcemia, hypokalemia, or obstructive uropathy.

Correct Answer: C

Rationale: Tetany is a condition characterized by involuntary muscle spasms and contractions due to low levels of calcium in the blood. The signs associated with tetany include Trousseau's sign, which is the carpal spasm elicited by inflating a blood pressure cuff above systolic pressure, and Chvostek's sign, which is the facial muscle spasm elicited by tapping on the facial nerve. Peroneal sign is not specifically associated with tetany but can be seen in conditions like peroneal nerve injury. Erb's sign, on the other hand, is not a recognized sign of tetany. It is associated with Erb's palsy, a condition resulting from injury to the brachial plexus nerves, typically during childbirth. Tinel's sign, which is a tingling sensation elicited by tapping over a compressed nerve, is also not a characteristic sign of tetany.

Correct Answer: A

Rationale: Oxytocin is a hormone produced by the hypothalamus and released by the pituitary gland. In the bloodstream, oxytocin is mostly bound to a carrier protein called neurophysin. This binding helps to protect oxytocin from being degraded too quickly in the bloodstream, thus allowing it to exert its effects on target tissues such as the uterus and mammary glands. Oxytocin plays important roles in stimulating uterine contractions during labor, facilitating milk letdown during breastfeeding, and promoting social bonding and emotional connections.

Correct Answer: D

Rationale: Vanillylmandelic acid (VMA) is a metabolite of catecholamines, such as epinephrine and norepinephrine. Phaeochromocytoma is a catecholamine-secreting tumor that arises from the chromaffin cells in the adrenal medulla or sympathetic ganglia. As a result of the increased production of catecholamines in patients with phaeochromocytoma, there is an increase in VMA excretion in the urine. This increase in VMA excretion is a significant diagnostic feature of phaeochromocytoma and helps in its detection through urine testing. Therefore, the correct choice is D. Phaeochromocytoma.