AKT · Endocrine/Adrenal

Primary aldosteronism (Conn's)

Autonomous aldosterone excess (adrenal adenoma or bilateral hyperplasia)

Overview

Autonomous aldosterone overproduction — bilateral adrenal hyperplasia or an aldosterone-producing adenoma (Conn's). The commonest secondary/curable cause of hypertension. Causes hypertension with (sometimes) hypokalaemia and metabolic alkalosis. Screen with the aldosterone:renin ratio; treat with a mineralocorticoid antagonist or adrenalectomy.

Recognise

Hypertension — often resistant or in a younger person — with HYPOKALAEMIA (cramps, weakness, polyuria) and metabolic alkalosis; potassium may be normal
Suppressed renin with raised aldosterone
Consider in resistant hypertension, hypertension + hypokalaemia, or hypertension + adrenal incidentaloma

Red flags

Severe hypokalaemia → arrhythmia risk
Resistant hypertension → screen for this curable cause

Differentials & how to tell them apart

Essential hypertensionnormal aldosterone:renin ratio

Secondary hyperaldosteronism (renal artery stenosis, heart failure)HIGH renin (driven by reduced renal perfusion) — not suppressed

Cushing's / liquorice / Liddle syndromeother causes of hypertension + hypokalaemia — different biochemistry

Phaeochromocytomaparoxysmal symptoms, raised metanephrines

Investigations

Aldosterone:renin RATIO (raised — high aldosterone, suppressed renin) as the screen; confirm with saline suppression. Then CT adrenals + adrenal vein sampling to distinguish unilateral adenoma from bilateral hyperplasia.

Management

Spironolactone/eplerenone (bilateral); adrenalectomy (unilateral adenoma)

1Screen resistant/hypokalaemic hypertension with the aldosterone:renin ratio (stop interfering drugs); confirm, then CT + adrenal vein sampling to lateralise.Gate: Distinguish UNILATERAL adenoma (→ adrenalectomy, potentially curative) from BILATERAL hyperplasia (→ lifelong mineralocorticoid antagonist) — adrenal vein sampling, not CT alone, decides this
2Unilateral → laparoscopic adrenalectomy; bilateral → spironolactone/eplerenone; correct potassium and BP.

Mineralocorticoid receptor antagonist (spironolactone/eplerenone) — first-line medical treatment, esp. bilateral hyperplasia; spironolactone → gynaecomastia

Adrenalectomy — for a unilateral aldosterone-producing adenoma (Conn's)

Key points

Resistant hypertension ± hypokalaemia with a high aldosterone:renin ratio = Conn's — a curable cause of hypertension. Adrenal vein sampling decides surgery vs lifelong spironolactone. High renin instead = secondary (renal artery stenosis).

Monitor & prognosis

BP, potassium; post-adrenalectomy cure.

Curable (unilateral) or controllable (bilateral).

Source: Endocrine Society; NICE hypertension