Endocrinology Exam Questions and Answers

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: 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: 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.

Correct Answer: B

Rationale: Prolactin levels can be increased by various factors, including chest wall trauma, pregnancy, and renal failure. However, hyperthyroidism is not typically associated with elevated prolactin levels. In fact, hyperthyroidism is more commonly associated with decreased levels of prolactin due to the inhibitory effect of thyroid hormones on prolactin secretion. Therefore, all of the options except for hyperthyroidism would be expected to increase prolactin levels.

Correct Answer: B

Rationale: Hemoglobin A1c, also known as HbA1c or glycated hemoglobin, is a blood test that measures the average blood glucose level over the previous 2 to 3 months. This test is useful in monitoring long-term blood glucose control in individuals with diabetes. Hemoglobin A1c provides an indication of how well blood glucose levels have been controlled over time, reflecting the average blood sugar levels during the lifespan of red blood cells, which is typically around 2 to 3 months. A higher Hemoglobin A1c level indicates poorer blood glucose control and an increased risk of diabetes complications.