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Primary Aldosteronism (Conn Syndrome) — RACP Adult Medicine MCQ

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ModerateEndocrinologyPrimary Aldosteronism (Conn Syndrome)RACP Adult Medicine

A 40-year-old woman presents with resistant hypertension, hypokalaemia (K⁺ 2.9 mmol/L), and metabolic alkalosis. Aldosterone:renin ratio is 65 (elevated). Confirmatory saline infusion test shows non-suppressible aldosterone (450 pmol/L post-infusion). CT shows a 1.5 cm left adrenal adenoma. Adrenal vein sampling confirms unilateral left-sided aldosterone secretion. What is the most likely diagnosis?

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Correct answer: C — Primary aldosteronism

Resistant hypertension with hypokalaemia, metabolic alkalosis, elevated ARR, non-suppressible aldosterone, and adrenal adenoma with lateralisation on AVS confirms unilateral aldosterone-producing adenoma (Conn syndrome). Laparoscopic adrenalectomy is curative. AVS is the gold standard for subtype differentiation (unilateral adenoma vs bilateral hyperplasia).

Reference: Endocrine Society – 2016 – Primary Aldosteronism; ESA 2024