Calcium and Parathyroid USMLE Step 1 Practice Question
A 68-year-old woman with no significant past medical history presents with confusion, nausea, and nephrolithiasis. Vital signs show BP 138/82 mmHg, HR 88/min, RR 16/min, temperature 37.2°C. Laboratory studies reveal serum calcium 12.1 mg/dL, phosphate 2.0 mg/dL, PTH 145 pg/mL, and 24-hour urine calcium 320 mg/day. Imaging shows a 4-mm stone in the right ureter. Renal function is normal. Which is the most appropriate next diagnostic step?
Answer choices
- A24-hour urine calcium excretion
- BBone marrow biopsy
- CParathyroid imaging with sestamibi scan or ultrasoundCorrect answer
- DPTHrP level
- ESerum 1,25-dihydroxyvitamin D level
- FThyroid ultrasound and thyroid-stimulating hormone level
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