Adrenal Disorders USMLE Step 1 Practice Question
A 38-year-old man with confirmed Cushing syndrome undergoes high-dose dexamethasone suppression testing. His 24-hour urinary free cortisol decreases from 350 µg/24h to 85 µg/24h (normal <50) after high-dose suppression. ACTH is elevated at 68 pg/mL. MRI of the pituitary shows a 6-mm adenoma. Which of the following is the most likely diagnosis?
Answer choices
- APrimary adrenal insufficiency
- BPrimary adrenal adenoma
- CCushing disease (pituitary adenoma)Correct answer
- DAdrenal carcinoma
- EEctopic ACTH secretion
- FFamilial glucocorticoid deficiency
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