Expansion
Hypertension with hypokalaemia, high aldosterone and suppressed renin
Expansion
Features
- Hypertension, often resistant to three or more drugs
- Hypokalaemia (present in only about a third, so its absence does not exclude)
- Metabolic alkalosis
- Sodium normal or only slightly raised, because of aldosterone escape
- Often no oedema, for the same reason
Causes: bilateral adrenal hyperplasia (about two-thirds) and unilateral adenoma (Conn syndrome, about one-third).
Investigation
- Screen with the aldosterone to renin ratio: aldosterone high with renin suppressed
- Confirm with a saline suppression or fludrocortisone test
- Localise with CT and, crucially, adrenal vein sampling, since adrenal incidentalomas are common and imaging alone misleads
Secondary hyperaldosteronism has high renin as well as high aldosterone, and occurs in renal artery stenosis, heart failure, cirrhosis and diuretic use.
It is now recognised in 5 to 10 per cent of hypertensive patients, and matters because unilateral disease is curable by adrenalectomy and bilateral disease responds well to mineralocorticoid receptor antagonists.