In simple terms
Primary aldosteronism is a hormone disorder in which the adrenal glands, which sit on top of the kidneys, release too much aldosterone. The extra hormone pushes blood pressure up.
It is also called Conn syndrome. The word primary means the problem starts in the adrenal glands themselves.
How it works
Aldosterone tells the kidneys to keep sodium and water and to pass potassium into the urine. Keeping sodium and water expands the volume of blood, and higher volume means higher pressure.
Two patterns account for almost every case: overgrowth of tissue in both adrenal glands, and a benign tumor on one gland. Trusted sources report different splits. Johns Hopkins puts overactive tissue at 60 to 70 percent and a single tumor at 30 to 40 percent. The StatPearls reference in the NIH Bookshelf reverses the weighting, at 40 to 50 percent and 50 to 60 percent.
Testing starts with blood levels of aldosterone and of renin, a kidney hormone. Dynamic tests, such as saline suppression or a captopril challenge, are used to confirm a result and to show whether one gland or both are involved.
Potassium is often low, and low potassium can cause muscle cramps, weakness and fatigue. It is not always low. StatPearls reports that 38 percent of patients have normal potassium.
Why it matters
StatPearls reports primary aldosteronism in 6 to 20 percent of adults with high blood pressure, and in about 30 percent of people whose blood pressure stays high despite treatment. That makes it one of the more common causes of high blood pressure with a specific, identifiable source.
This entry explains the term only. Decisions about testing, medicines or surgery belong with a clinician who knows the person’s history.
Where you’ll see it
- Endocrine Society guidance on who should be screened
- Blood test reports listing aldosterone and renin
- Research into why blood pressure medicines fail for some people
- News coverage of wearable hormone monitors
Example
A patient whose blood pressure stays high on three medicines is screened with an aldosterone and renin test, and the result points to the adrenal glands rather than to the medicines.
Often confused with
Primary aldosteronism is a cause, not a category of blood pressure. Resistant hypertension describes blood pressure that stays high on several medicines. Primary aldosteronism is one reason that happens.
Key facts
- Primary aldosteronism is increased aldosterone secretion from the adrenal glands, with suppressed plasma renin, high blood pressure and often low potassium.1
- It is reported in 6 to 20 percent of adults with high blood pressure, and in about 30 percent of people with resistant hypertension.1
- About 38 percent of patients have normal potassium levels, so a normal potassium result does not rule the condition out.1
- Johns Hopkins attributes 60 to 70 percent of cases to overactive adrenal tissue and 30 to 40 percent to a benign tumor on one gland.2
- Diagnosis begins with blood aldosterone and renin levels, then dynamic tests such as saline suppression or a captopril challenge.2
This entry explains a medical term. It is not medical advice. If you are concerned about your health, speak with a qualified health professional.
Go deeperWhat Actually Causes High Blood Pressure?Related concepts
In the news
Quick checkWhy is primary aldosteronism often missed?Show answer
Potassium is normal in about 38 percent of patients, and finding it needs a specific aldosterone and renin test rather than routine bloodwork.
Sources
- StatPearls Publishing, NIH National Library of Medicine Bookshelf. Conn Syndrome. 12 September 2022 (accessed 17 September 2026)
- Johns Hopkins Medicine. Primary Aldosteronism. 21 September 2022 (accessed 17 September 2026)
Editorially reviewed by Specialty Digest Editorial TeamLast reviewed September 17, 2026Researched and drafted with AI assistanceReport an issue