Pituitary Disorders USMLE Step 1 Practice Question
A 67-year-old man with a 3-month chronic cough presents with malaise and polyuria. Vital signs: BP 138/82, HR 88, RR 16, Temp 37.2°C, SpO2 98% on room air. Labs reveal serum calcium 12.5 mg/dL, PTH 10 pg/mL (low), and elevated 1,25-dihydroxyvitamin D. Chest CT shows a small nodular lung opacity. Serum phosphate is normal. Which mechanism best explains his hypercalcemia?
Answer choices
- AEctopic PTHrP secretion from lung carcinoma
- BPrimary hyperparathyroidism with incidental lung lesion
- CThyrotoxicosis with increased bone resorption
- DEctopic calcitriol production from granulomatous lung diseaseCorrect answer
- EVitamin D intoxication from dietary supplementation
- FOsteolytic bone metastases with prostaglandin-mediated local calcium release
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