Thyroid Disorders USMLE Step 1 Practice Question
A 41-year-old man presents with a 3-month history of chronic watery diarrhea and is found to have a thyroid nodule on examination. Vital signs show BP 148/92 mmHg, HR 102 bpm, RR 18, temperature 37°C, SpO2 98%. His sister underwent surgery for pheochromocytoma. Fine needle aspiration reveals a neuroendocrine tumor derived from parafollicular cells. Serum calcitonin is markedly elevated at 850 pg/mL. There is no palpable lymphadenopathy. Which substance is most likely elevated?
Answer choices
- AThyroglobulin
- BTSH receptor antibodies
- CThyroid peroxidase antibodies
- DParathyroid hormone
- ECalcitoninCorrect answer
- FVasoactive intestinal peptide
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