Calcium and Parathyroid USMLE Step 1 Practice Question
A 55-year-old man with a 20 pack-year smoking history presents with bone pain and polyuria. Vital signs show BP 138/88, HR 92, RR 18, temp 37.2°C, SpO2 98%. Laboratory studies reveal serum calcium 11.8 mg/dL, suppressed PTH 5 pg/mL, elevated PTHrP 120 pmol/L, and normal 1,25-vitamin D levels. Chest CT demonstrates a 4 cm left upper lobe mass. He denies recent weight loss. Which malignancy is most likely responsible for his hypercalcemia?
Answer choices
- AOsteolytic breast cancer metastases
- BSquamous cell carcinoma of the lungCorrect answer
- CMultiple myeloma with osteoclast activation
- DHodgkin lymphoma with granulomatous production of 1,25-vitamin D
- ESmall cell lung cancer with ectopic calcitriol production
- FRenal cell carcinoma with production of parathyroid hormone-related peptide
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