MD Endocrine and Metabolic Disorders 4 — Questions and Answers
Question 1: A 25-year-old woman has muscle cramps, perioral tingling, and a positive Chvostek sign after thyroid surgery. Labs show calcium 7.0 mg/dL and PTH 5 pg/mL. What is the diagnosis?
- Hypomagnesemia
- Hypoparathyroidism (Correct answer)
- Pseudohypoparathyroidism
- Vitamin D deficiency
Correct answer: Hypoparathyroidism
Surgical removal or damage to parathyroid glands causes hypoparathyroidism with low calcium and very low PTH.
Question 2: A patient with type 2 diabetes on metformin has an HbA1c of 8.5%. The provider adds an SGLT2 inhibitor. Which additional benefit beyond glucose control supports this choice in a patient with established cardiovascular disease?
- Reduction in HbA1c by 3%
- Decreased risk of major adverse cardiovascular events (Correct answer)
- Reversal of diabetic nephropathy
- Complete elimination of hypoglycemia risk
Correct answer: Decreased risk of major adverse cardiovascular events
SGLT2 inhibitors (e.g., empagliflozin, canagliflozin) have demonstrated significant reduction in MACE and heart failure hospitalization in patients with established CVD.
Question 3: A 45-year-old man has hypertension, hypokalemia, and a plasma aldosterone-to-renin ratio of 35 (elevated). What is the most likely diagnosis?
- Renovascular hypertension
- Primary hyperaldosteronism (Conn's syndrome) (Correct answer)
- Cushing's syndrome
- Pheochromocytoma
Correct answer: Primary hyperaldosteronism (Conn's syndrome)
An elevated aldosterone-to-renin ratio with hypokalemia and hypertension is the hallmark of primary hyperaldosteronism due to autonomous aldosterone secretion.
Question 4: A newborn presents with ambiguous genitalia, vomiting, and hyponatremia with hyperkalemia. 17-hydroxyprogesterone is markedly elevated. What enzyme is deficient?
- 11-beta hydroxylase
- 21-hydroxylase (Correct answer)
- 17-alpha hydroxylase
- 3-beta hydroxysteroid dehydrogenase
Correct answer: 21-hydroxylase
21-hydroxylase deficiency is the most common cause of congenital adrenal hyperplasia, blocking cortisol and aldosterone synthesis with excess 17-OHP accumulation.
Question 5: A 60-year-old woman with osteoporosis has a serum calcium of 11.8 mg/dL, low phosphorus, and PTH of 120 pg/mL. Neck ultrasound shows a right inferior parathyroid adenoma. What is the definitive treatment?
- Cinacalcet indefinitely
- Bisphosphonate therapy
- Parathyroidectomy (Correct answer)
- Thiazide diuretics to increase calcium reabsorption
Correct answer: Parathyroidectomy
Parathyroidectomy is the definitive curative treatment for symptomatic primary hyperparathyroidism, including cases with osteoporosis or nephrolithiasis.
Question 6: A patient with newly diagnosed hypothyroidism is started on levothyroxine. When should TSH be rechecked to assess adequacy of dosing?
- After 1 week
- After 4–6 weeks (Correct answer)
- After 6 months
- Only when symptoms recur
Correct answer: After 4–6 weeks
TSH has a half-life that requires 4–6 weeks for a new steady state to be reached after initiating or adjusting levothyroxine therapy.
Question 7: A 48-year-old man with acromegaly has elevated IGF-1 and a GH level that does not suppress to <1 ng/mL after oral glucose load. What is the first-line treatment?
- Octreotide (somatostatin analogue)
- Dopamine agonist (cabergoline)
- Transsphenoidal surgical resection (Correct answer)
- Pegvisomant (GH receptor antagonist)
Correct answer: Transsphenoidal surgical resection
Transsphenoidal surgery is the first-line treatment for acromegaly, offering the best chance of cure especially for microadenomas and non-invasive macroadenomas.
MD Endocrine and Metabolic Disorders 4
A 25-year-old woman has muscle cramps, perioral tingling, and a positive Chvostek sign after thyroid surgery.
Labs show calcium 7.0 mg/dL and PTH 5 pg/mL.
What is the diagnosis?