Pituitary Disorders USMLE Step 1 Practice Question
A 37-year-old man with hypertension presents with hypokalemia and metabolic alkalosis. Vital signs show BP 158/96 mmHg, HR 88, RR 14, temp 37°C, SpO2 98%. Laboratory studies reveal potassium 2.8 mEq/L and bicarbonate 32 mEq/L. High-dose dexamethasone suppression test shows 8 AM cortisol 12 μg/dL (baseline 42 μg/dL) with ACTH 65 pg/mL. Plasma renin activity is normal. Which diagnosis best explains these findings?
Answer choices
- AEctopic ACTH-secreting neoplasmCorrect answer
- BAdrenal adenoma producing cortisol
- CACTH-secreting pituitary adenoma
- DPrimary adrenocortical carcinoma
- EIatrogenic Cushing syndrome from glucocorticoid use
- FPrimary hyperaldosteronism from an adrenal adenoma
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