Endocrinology Flashcards

A 45-year-old woman with type 2 diabetes on metformin has an eGFR that drops to 28 mL/min/1.73m². Which medication adjustment is most appropriate?

Answer: Discontinue metformin

Metformin is contraindicated when eGFR falls below 30 mL/min/1.73m² due to risk of lactic acidosis.

A patient with Cushing's disease undergoes transsphenoidal surgery. Post-operatively, serum cortisol is 2 mcg/dL. What does this indicate?

Answer: Adrenal insufficiency requiring glucocorticoid replacement

Very low post-operative cortisol indicates successful tumor removal but requires exogenous glucocorticoid replacement until the HPA axis recovers.

Which finding on thyroid ultrasound carries the HIGHEST risk of malignancy?

Answer: Hypoechoic nodule with microcalcifications and irregular margins

Hypoechoic nodules with microcalcifications and irregular margins carry the highest malignancy risk and warrant FNA biopsy.

A 32-year-old woman presents with galactorrhea, amenorrhea, and a prolactin level of 210 ng/mL. MRI shows a 12 mm pituitary lesion. First-line treatment is:

Answer: Bromocriptine or cabergoline

Dopamine agonists (cabergoline preferred) are first-line treatment for prolactinomas regardless of size.

A patient with type 1 diabetes develops recurrent hypoglycemia without adrenergic warning symptoms. This condition is best described as:

Answer: Hypoglycemia-associated autonomic failure

Hypoglycemia-associated autonomic failure (HAAF) results from prior hypoglycemic episodes blunting counter-regulatory and symptomatic responses.

Phentolamine is administered before surgical resection of a pheochromocytoma. What is its primary purpose?

Answer: Block alpha-adrenergic receptors to prevent hypertensive crisis

Alpha-blockade with phentolamine (or phenoxybenzamine) is essential to prevent severe hypertension from catecholamine release during tumor manipulation.

A 55-year-old man has serum calcium of 11.4 mg/dL, PTH of 95 pg/mL (normal 15–65), and normal renal function. Urine calcium-to-creatinine clearance ratio is 0.005. What is the most likely diagnosis?

Answer: Familial hypocalciuric hypercalcemia

A urine calcium-to-creatinine clearance ratio <0.01 with hypercalcemia and elevated PTH indicates familial hypocalciuric hypercalcemia (FHH), not primary hyperparathyroidism.