Hyperaldosteronism

Primary hyperaldosteronism — most commonly an aldosterone-secreting adenoma (Conn syndrome) or bilateral adrenal hyperplasia. An important and under-recognised cause of secondary/resistant hypertension.

Clinical features

• Elevated blood pressure (often resistant to multiple anti-hypertensives)
• Hypokalaemia (only present in ~30%) — weakness, cramps, paraesthesia, polyuria, polydipsia; many patients are otherwise asymptomatic
• Aldosterone excess with suppressed plasma renin

Investigations

• Plasma aldosterone-to-renin ratio (ARR) — the screening test; a raised ratio (high aldosterone, low renin) is positive. Many antihypertensives and NSAIDs affect the ratio, so interpret with care (and adjust medications where possible before testing).
• Biochemistry may show raised Na⁺ and low K⁺.
• CT/MRI of the adrenals (± adrenal vein sampling) to localise, once screening is positive.

Management

Refer to a specialist. An aldosterone-secreting adenoma (Conn syndrome) is usually treated with adrenalectomy; bilateral hyperplasia is managed medically with a mineralocorticoid-receptor antagonist (spironolactone or eplerenone).