Adrenal Disorders USMLE Step 1 Practice Question
A 42-year-old woman presents to the endocrinology clinic with a 6-month history of progressive facial plethora, easy bruising, proximal leg weakness, and irritability. Her blood pressure is 156/98 mmHg, and laboratory studies show serum potassium of 3.1 mEq/L. Screening tests reveal midnight salivary cortisol of 0.9 μg/dL (normal <0.1) and 24-hour urinary free cortisol of 295 μg/24h (normal <100). Plasma ACTH is 62 pg/mL (normal 10-46). A subsequent high-dose dexamethasone suppression test (8 mg overnight) shows morning serum cortisol of 3.2 μg/dL. Which of the following best explains these findings?
Answer choices
- APituitary adenoma secreting ACTH (Cushing disease)Correct answer
- BEctopic ACTH-secreting neuroendocrine tumor
- CAdrenal carcinoma producing cortisol and ACTH
- DPrimary bilateral adrenal hyperplasia
- EAutonomous cortisol-secreting adrenal adenoma
- FCushing syndrome secondary to severe depression
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