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Primary Aldosteronism — RACP Adult Medicine MCQ

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HardEndocrinology & DiabetesPrimary AldosteronismRACP Adult Medicine

A 40-year-old woman presents with episodic hypertension, hypokalaemia (K+ 2.8 mmol/L), and metabolic alkalosis. Her aldosterone-to-renin ratio is markedly elevated. A CT adrenal shows a 1.8 cm left adrenal adenoma. Before considering surgery, what is the confirmatory test?

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Correct answer: B — Saline suppression test or fludrocortisone suppression test

A confirmatory test is required before proceeding to lateralisation studies or surgery. The saline infusion test (2 L 0.9% saline IV over 4 hours; failure to suppress aldosterone below 140 pmol/L confirms primary aldosteronism) or oral fludrocortisone suppression test are the recommended confirmatory investigations. Adrenal venous sampling is subsequently performed to confirm lateralisation before considering adrenalectomy, particularly in patients >35 years (to distinguish adenoma from bilateral hyperplasia).

Reference: eTG – 2025 – Endocrinology; Endocrine Society – 2016 – Primary Aldosteronism Guidelines