Primary aldosteronism is a condition where one or both adrenal glands produce too much of a hormone called aldosterone, leading to high blood pressure that can be difficult to control with standard medications. It affects at least 10% of people with hypertension and more than 20% of those with treatment-resistant hypertension, making it the leading hormonal cause of high blood pressure. Despite being common, it remains widely underdiagnosed.
How Excess Aldosterone Raises Blood Pressure
Your two adrenal glands sit on top of your kidneys and produce aldosterone, a hormone that tells the kidneys how much sodium and water to hold onto. In primary aldosteronism, the adrenals release aldosterone regardless of whether your body actually needs it. The excess hormone forces the kidneys to retain sodium and water, which increases blood volume and drives up blood pressure. At the same time, the kidneys flush out potassium to compensate, which can cause potassium levels to drop.
There are two main forms. In the first, a small noncancerous growth on one adrenal gland (sometimes called Conn’s syndrome) churns out extra aldosterone on its own. In the second, both adrenal glands are overactive, a condition known as bilateral adrenal hyperplasia. The bilateral form is more common overall. Which type you have determines whether surgery is an option or whether long-term medication is the better path.
Symptoms and Warning Signs
The most prominent feature of primary aldosteronism is high blood pressure, often resistant to the usual medications. Many people take two or three blood pressure drugs and still can’t reach normal levels. That pattern alone is one of the strongest clues.
Low potassium is the other hallmark, though it shows up in only 9 to 37% of cases, so normal potassium levels don’t rule out the condition. When potassium does drop, it can cause muscle cramps, weakness, fatigue, frequent urination, and excessive thirst. In severe cases, dangerously low potassium can trigger heart rhythm problems. Many people with primary aldosteronism, however, feel no obvious symptoms at all. Their blood pressure simply won’t cooperate with treatment.
Cardiovascular Risks Beyond Blood Pressure
Primary aldosteronism does more damage than high blood pressure alone. Excess aldosterone directly injures blood vessels, the heart, and the kidneys in ways that go beyond what elevated pressure would explain. Compared to people with ordinary high blood pressure at similar levels, those with primary aldosteronism face roughly 2.5 times the risk of stroke, about 3 times the risk of atrial fibrillation (an irregular heart rhythm), and about twice the risk of heart failure. This is why identifying and treating the condition matters so much, even if blood pressure numbers look similar on paper.
Who Should Be Screened
The Endocrine Society’s most recent clinical practice guideline recommends screening all individuals with hypertension by measuring aldosterone and renin levels. In practice, screening rates remain low, so certain groups deserve particular attention: people whose blood pressure stays high despite three or more medications, anyone with unexplained low potassium, people who develop hypertension before age 40, and those with an adrenal mass found incidentally on imaging.
The initial screening test is the aldosterone-to-renin ratio, a simple blood draw. In primary aldosteronism, aldosterone runs high while renin (a kidney enzyme that normally stimulates aldosterone production) is suppressed, because the adrenals are acting on their own. A ratio above certain thresholds flags the need for further testing. Some blood pressure medications can skew these results, so your doctor may switch you to alternatives that don’t interfere with the test for about four weeks beforehand.
Confirming the Diagnosis
A positive screening result doesn’t confirm primary aldosteronism on its own. A confirmatory test is needed. The most widely used is the saline infusion test, where you receive a salt-water IV over several hours. Normally, flooding the body with sodium suppresses aldosterone production. If aldosterone levels remain elevated after the infusion, it confirms the adrenal glands are producing the hormone independently.
Once primary aldosteronism is confirmed, the next step is figuring out whether one or both adrenal glands are responsible. This distinction drives the entire treatment plan. A CT scan can show whether there’s a visible growth on one gland, but imaging alone isn’t always reliable. A specialized procedure called adrenal vein sampling, where blood is drawn directly from the veins draining each adrenal gland, is the gold standard. Patients diagnosed through adrenal vein sampling achieved complete biochemical cure 93% of the time after surgery, compared to 80% for those diagnosed by CT alone. For younger patients with a clear-cut presentation on imaging, CT-based decisions can work well, but adrenal vein sampling remains the preferred approach in most cases. It is technically challenging, though, and not available at every medical center.
Surgery for One-Sided Disease
When a single adrenal gland is the source, the standard treatment is removing that gland through a minimally invasive laparoscopic procedure. The remaining adrenal gland takes over normal hormone production without difficulty.
A meta-analysis of about 4,000 patients found that roughly half achieved a complete cure of their hypertension after surgery, meaning normal blood pressure with no medications at all. The other half still needed some blood pressure medication but typically fewer drugs at lower doses than before. Several factors influence who gets a full cure: younger patients, those with shorter duration of hypertension, and people without significant kidney damage tend to do best. Even when blood pressure isn’t fully normalized, surgery reliably corrects the excess aldosterone, which removes the extra cardiovascular damage the hormone causes.
Medication for Bilateral Disease
When both adrenal glands are overactive, removing them isn’t practical since you need at least one functioning gland. Instead, treatment relies on medications that block aldosterone’s effects at the cellular level.
Spironolactone, typically prescribed at 50 to 100 mg daily, is the most established option and effectively lowers blood pressure while correcting potassium levels. Its main drawback is that it can cause breast tenderness and breast tissue growth in men, along with menstrual irregularities in women, because it interacts with sex hormone receptors in addition to blocking aldosterone. Eplerenone, dosed at 25 to 50 mg daily, is a more targeted alternative that largely avoids these hormonal side effects, though it may be somewhat less potent. Both medications can raise potassium levels too much, so periodic blood work is necessary, especially early in treatment or if you have any degree of kidney impairment.
Most people on these medications see significant improvement in blood pressure control and can reduce or eliminate some of their other blood pressure drugs. The medications also protect the heart, blood vessels, and kidneys from the direct damage excess aldosterone causes, which is just as important as the blood pressure reduction itself.