If you have high blood pressure, there is a hormone test your routine panel almost certainly skipped.

What it is. Aldosterone is an adrenal hormone that tells the kidneys to hold on to sodium and let potassium go. In primary aldosteronism, the adrenals make it regardless of what the body needs, so blood pressure rises and renin, the signal that normally switches aldosterone on, gets pushed down. The Endocrine Society’s 2025 release estimates it in 5% to 14% of people with high blood pressure seen in primary care and up to 30% of those seen in referral centers. Left untreated, the same release says, it raises the risk of stroke, coronary artery disease, atrial fibrillation, heart failure and kidney disease.

What changed in 2025. Recommendation 1 of the Endocrine Society guideline, published in the Journal of Clinical Endocrinology & Metabolism in July 2025, reads: “In all individuals with hypertension, we suggest screening for primary aldosteronism.” The previous version screened only higher-risk groups, such as people with resistant hypertension or low potassium. The word is “suggest”, a conditional recommendation on low-certainty evidence; the release says the panel chose it because the blood test can return false positives.

Why your panel did not catch it. A comprehensive metabolic panel measures potassium and sodium. It does not measure aldosterone or renin; those are separate tests that have to be ordered by name. Low potassium alongside high blood pressure is the textbook prompt, but the 2016 Endocrine Society guideline reported low potassium in only 9% to 37% of people with primary aldosteronism. So an unremarkable potassium on your report is not evidence against it. A low one, with no diuretic to explain it, is a reason to ask.

What the screen involves. Per the guideline, the lab measures aldosterone and renin from a morning draw taken while you are seated, with potassium measured alongside, and reads them as an aldosterone-to-renin ratio together with the absolute values. A suppressed renin with an aldosterone that is not suppressed is a positive screen. A positive screen is not a diagnosis: the guideline describes confirmatory testing for some people, and adrenal imaging plus adrenal vein sampling for anyone considering surgery.

Your medications matter, and you should not stop them yourself. Several common blood pressure drugs move renin and aldosterone. The guideline lists withdrawal windows where stopping is safe and feasible: four weeks for mineralocorticoid receptor antagonists such as spironolactone, ENaC inhibitors and diuretics, and two weeks for ACE inhibitors and ARBs. It also describes a no-withdrawal approach that tests on your current medications and interprets the result with them in mind. Which one applies is a decision for the clinician ordering the test.

Why it is worth finding. Primary aldosteronism has its own treatment. The guideline suggests PA-specific therapy: surgery when the excess comes from one adrenal gland, or a mineralocorticoid receptor antagonist, with spironolactone preferred for its low cost and availability. A person whose blood pressure is driven by aldosterone and treated only with general blood pressure drugs is being treated for the number, not the cause.

What to do with this. If you have high blood pressure and your records show no aldosterone or renin result, ask whether screening applies to you. Ask sooner if your potassium has come back low, if your blood pressure needs three or more drugs, or if a close relative had high blood pressure or a stroke before 40. Those were among the higher-risk groups the 2016 guideline screened. If your report shows a low potassium, our metabolic panel guide explains what the potassium bands mean and when a low value counts as flagged.