Calcium and Parathyroid USMLE Step 1 Practice Question
A 60-year-old man presents to his primary care physician with progressive dysphagia and a palpable firm nodule in the lower neck. He denies weight loss, fever, or family history of endocrine disorders. Vital signs are stable. Laboratory studies show serum calcium 10.8 mg/dL (normal 8.5-10.5), serum phosphate 3.2 mg/dL (normal 2.5-4.5), and serum calcitonin 450 pg/mL (normal <10 pg/mL). Fine-needle aspiration biopsy of the thyroid nodule demonstrates malignant spindle and polygonal cells arranged in a characteristic amyloid-rich stroma. Which of the following hormones is normally produced by the cell type from which this malignancy arises?
Answer choices
- AParathyroid hormone
- BThyroxine (T4)
- CTriiodothyronine (T3)
- DThyroid peroxidase
- ECalcitoninCorrect answer
- FAdrenocorticotropic hormone
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