A 45-year-old man has hypertension, hypokalemia, and metabolic alkalosis. Adrenal CT shows a 1.8 cm left adrenal adenoma. Aldosterone-to-renin ratio is markedly elevated. The pathological adrenal cortical zone from which this adenoma arises is:

• A Zona reticularis
• B Zona fasciculata
• C Adrenal medulla
• D Zona glomerulosa ✓

Explanation

Conn syndrome (primary hyperaldosteronism) is due to an adenoma arising from the zona glomerulosa, the outermost zone of the adrenal cortex normally producing aldosterone. Aldosterone excess causes sodium retention, hypertension, and potassium wasting (hypokalemia with metabolic alkalosis). The zona fasciculata produces cortisol; the zona reticularis produces androgens; the medulla produces catecholamines.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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