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Primary aldosteronism and secondary hypertension
Resistant hypertension, hypertension with hypokalaemia or hypertension with an adrenal mass call for screening for primary aldosteronism with the aldosterone-renin ratio; once confirmed, a unilateral adenoma (surgery) is separated from bilateral hyperplasia (MRA).
Why it matters in the exam
Primary aldosteronism is the commonest endocrine cause of secondary hypertension, and the question usually presents a patient whose blood pressure is uncontrolled on three drugs (including a diuretic), or one with hypertension and spontaneous hypokalaemia. The screening test is a morning aldosterone-renin ratio, after correcting hypokalaemia; spironolactone interferes with the test and is stopped several weeks beforehand when possible. A positive ratio needs a confirmatory test (salt or saline loading), unless there is spontaneous hypokalaemia, undetectable renin and a very high aldosterone. Then adrenal CT, and in a surgical candidate — adrenal venous sampling, because CT alone misleads.
Further questions deal with other causes of secondary hypertension: renal artery stenosis — fibromuscular dysplasia in a young woman (treated with balloon angioplasty) or atherosclerotic in an older patient (mainly medical treatment), with clues such as a creatinine rise of more than 30% after an ACEi, an abdominal bruit and "flash" pulmonary oedema; kidney disease; obstructive sleep apnoea; Cushing syndrome; phaeochromocytoma; thyroid disease; coarctation in a young person (delay between arm and femoral pulses); and drugs and substances — NSAIDs, the pill, decongestants and liquorice, which causes apparent mineralocorticoid excess with low renin and aldosterone.
Key points
- Screen in resistant hypertension, hypokalaemia, adrenal mass and sleep apnoea.
- Aldosterone-renin ratio, then a confirmatory test.
- CT and adrenal venous sampling before surgery.
- Unilateral — adrenalectomy; bilateral — spironolactone or eplerenone.
- Other causes: renal artery, kidney, sleep apnoea, Cushing, phaeochromocytoma, drugs and liquorice.
Summary table
| Situation | Clue | Test | Treatment |
|---|---|---|---|
| When to screen | Resistant hypertension, hypokalaemia, adrenal mass, sleep apnoea, relative with aldosteronism | Aldosterone-renin ratio | Correct potassium before the test |
| Confirmation | Positive ratio | Salt or saline loading | Skipped with spontaneous hypokalaemia and undetectable renin |
| Unilateral adenoma | CT and adrenal venous sampling | Secretion from one side | Laparoscopic adrenalectomy |
| Bilateral hyperplasia | Secretion from both sides | — | Spironolactone or eplerenone |
| Renal artery stenosis | Young woman (FMD) or older atherosclerotic; creatinine up more than 30% on ACEi | Doppler, CTA or MRA | FMD: balloon; atherosclerotic: medical |
| Liquorice | Hypokalaemia and hypertension | Low renin and aldosterone | Stop the liquorice |
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Sources
- Endocrine Society Clinical Practice Guideline: Management of Primary Aldosteronism, 2016 — Case detection, confirmation, subtype and treatment
- ESH Guidelines for the management of arterial hypertension, 2023 — Secondary hypertension: when and how to screen
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Hypertensive Vascular Disease: secondary causes
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.