Calcium and Parathyroid USMLE Step 1 Practice Question
A 58-year-old man with hypertension presents with muscle weakness and polyuria. Vital signs: BP 148/92 mmHg, HR 88 bpm, RR 14, Temp 37°C, SpO2 98%. He takes hydrochlorothiazide. Serum calcium is 10.8 mg/dL, PTH 52 pg/mL, and 24-hour urinary calcium 450 mg (normal <300). Parathyroid ultrasound reveals a 1.2 cm nodule. Serum phosphate is normal. Which finding should prompt reconsideration of the diagnosis?
Answer choices
- AThiazide diuretics are contraindicated in all cases of hypercalcemia
- BFamilial hypocalciuric hypercalcemia presents with hypercalcemia and low urinary calciumCorrect answer
- CPTH level of 52 pg/mL excludes secondary causes of hypercalcemia
- DA single parathyroid nodule rules out any other etiology
- EElevated 24-hour urinary calcium excretion in primary hyperparathyroidism is expected
- FSerum phosphate levels are always low in primary hyperparathyroidism
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