Aldosterone
Aldosterone is a mineralocorticoid hormone made by the adrenal cortex. It acts on the kidneys to retain sodium and excrete potassium and hydrogen ions, raising blood volume and blood pressure. Aldosterone testing (often with a plasma renin activity ratio) is used to evaluate secondary or resistant hypertension, unexplained hypokalemia, and adrenal disorders. Primary aldosteronism is underdiagnosed and is a treatable cause of hypertension in 5–15% of hypertensive patients.
Reference Ranges
Male
3 – 16
ng/dL
Female
3 – 16
ng/dL
Child
Consult pediatrician
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
Low aldosterone with high potassium suggests adrenal insufficiency, type 4 renal tubular acidosis (hyporeninemic hypoaldosteronism, often in diabetes), or medications (spironolactone, eplerenone, ACE inhibitors, ARBs, NSAIDs). Isolated hypoaldosteronism is rare; evaluation includes cortisol, ACTH, renin activity, and potassium.
What High Levels Mean
Elevated aldosterone, especially with suppressed renin (low aldosterone-renin ratio), suggests primary aldosteronism — Conn syndrome (adrenal adenoma) or bilateral adrenal hyperplasia. Both cause hypertension, often with low or low-normal potassium. Diagnosis is confirmed with saline infusion or oral salt-loading tests. Treatment is surgical for unilateral adenomas and medical (spironolactone, eplerenone) for bilateral disease.
Frequently Asked Questions
Who should be tested for primary aldosteronism?
Anyone with hypertension plus any of: spontaneous hypokalemia, unexplained hypokalemia on diuretics, resistant hypertension (uncontrolled on 3 drugs), early-onset hypertension, hypertension plus adrenal mass, or hypertension plus family history of aldosteronism or stroke at young age. Given under-diagnosis, some experts recommend screening all hypertensive patients at diagnosis.
What is the aldosterone-to-renin ratio?
The ARR is the standard screening test for primary aldosteronism. An elevated ARR (>20–30 ng/dL per ng/mL/hr) combined with aldosterone above 10 ng/dL is suggestive and triggers confirmatory testing. ACE inhibitors, ARBs, and beta-blockers affect the ratio and should ideally be stopped for 2–4 weeks before testing; hypokalemia must be corrected first.
Why does aldosterone vary with posture?
Standing activates the renin-angiotensin system and raises aldosterone. Supine values are lower and less sensitive for borderline cases. Most screening protocols use a morning upright sample, after 2 hours on feet and 5 minutes seated. Consistency between samples matters more than absolute values when monitoring over time.
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nmol/LThis information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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