skip to main content

Chronic hyperkalemia — USMLE Step 3 MCQ

Instant feedback + full explanation. One question, done properly.

HardInternal Medicine (Chronic Management)Chronic hyperkalemiaUSMLE Step 3

A 48-year-old with resistant hypertension and spontaneous hypokalemia has plasma renin activity below 0.2 ng/mL/h and aldosterone 28 ng/dL by immunoassay on repeat testing. CT shows a 1.6-cm left adrenal nodule and a normal right adrenal gland. He wants curative surgery. What should be done before selecting the operative side?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Perform adrenal venous sampling to distinguish unilateral from bilateral aldosterone production

The best answer is “Perform adrenal venous sampling to distinguish unilateral from bilateral aldosterone production”. Overt renin-independent aldosterone production with hypokalemia can obviate suppression testing, but anatomy alone does not reliably distinguish a functional adenoma from an incidental nodule or bilateral disease. A surgical candidate older than the narrow young-patient exception should undergo adrenal venous sampling after CT. The under-35 exception for marked disease with a unilateral lesion does not apply.

Reference: Endocrine Society Clinical Practice Guideline: Primary Aldosteronism: https://www.endocrine.org/clinical-practice-guidelines/primary-aldosteronism-2