Calcium and Parathyroid USMLE Step 1 Practice Question
A 62-year-old woman presents with fatigue, constipation, and mild confusion. Serum calcium is 11.8 mg/dL (normal 8.5-10.5), phosphate is 2.1 mg/dL (normal 2.5-4.5), and PTH is 145 pg/mL (normal 15-65). Imaging reveals a 1.2 cm nodule in the inferior pole of the left thyroid lobe. Which of the following is the most likely diagnosis?
Answer choices
- ATertiary hyperparathyroidism
- BSecondary hyperparathyroidism from chronic kidney disease
- CSarcoidosis with elevated 1,25-dihydroxyvitamin D
- DPrimary hyperparathyroidismCorrect answer
- EThyroid carcinoma with PTHrP secretion
- FFamilial hypocalciuric hypercalcemia with concurrent thyroid adenoma
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