Aldosteronism is a condition where your adrenal glands produce too much aldosterone, a hormone that controls sodium and potassium balance in your blood. The excess aldosterone drives up blood pressure and depletes potassium, often for years before anyone identifies the real cause. Among people with high blood pressure, estimates suggest anywhere from 1% to as many as 36% of those with treatment-resistant hypertension actually have primary aldosteronism as the underlying driver.
How Aldosterone Works in the Body
Aldosterone is made by your adrenal glands, two small organs that sit on top of your kidneys. Its job is to fine-tune how much sodium your kidneys keep and how much potassium they flush out. When aldosterone reaches the kidneys, it opens sodium channels in the walls of the kidney’s filtering tubes, letting sodium pass back into your bloodstream. For every sodium molecule that gets reabsorbed, a potassium molecule gets pushed out into your urine.
Sodium pulls water with it, so when more sodium stays in the blood, your blood volume increases and your blood pressure rises. In a healthy system, this process is tightly regulated. Your body makes more aldosterone when blood pressure drops or potassium climbs too high, and dials it back when balance is restored. In aldosteronism, that feedback loop breaks down, and the hormone keeps flowing regardless of what the body actually needs.
Primary vs. Secondary Aldosteronism
The two forms of aldosteronism differ in where the problem originates. Primary aldosteronism comes from the adrenal glands themselves. The most common cause is a benign (noncancerous) tumor on one adrenal gland, called an aldosterone-producing adenoma. The second most common cause is bilateral adrenal hyperplasia, where both adrenal glands become overactive. In either case, the glands produce aldosterone on their own, ignoring the body’s normal signals to stop.
Secondary aldosteronism comes from somewhere else in the body triggering the adrenal glands to overproduce. Heart failure, liver disease, kidney disease, and severe dehydration can all set off the chain reaction that tells the adrenals to ramp up aldosterone. In secondary aldosteronism, the adrenal glands are technically working as designed; they’re just responding to a signal that won’t shut off. Treatment focuses on the underlying condition rather than the adrenals.
Symptoms and Warning Signs
The hallmark of aldosteronism is high blood pressure that doesn’t respond well to standard medications. Many people take two or three blood pressure drugs and still can’t reach their target numbers. That treatment resistance is often the first clue that something beyond ordinary hypertension is going on.
Low potassium (hypokalemia) is the other major feature, though not everyone with aldosteronism develops it. When potassium drops low enough, symptoms become hard to ignore: muscle weakness (especially in the legs), cramping, fatigue, and excessive thirst paired with frequent urination. In one reported case, a 44-year-old woman developed such severe weakness in her lower limbs that she had difficulty walking, with recurring episodes over the course of a year before doctors traced the cause to an aldosterone-producing tumor. Heart rhythm changes can also appear, including flattened or abnormal waves on an electrocardiogram. In rare and severe cases, dangerously low potassium can cause muscle breakdown or temporary paralysis.
Cardiovascular Risks Beyond High Blood Pressure
Aldosteronism does more damage than hypertension alone. A controlled study published in the American Heart Association’s journal Hypertension found that people with primary aldosteronism had significantly higher rates of cardiovascular complications compared to people with the same degree of high blood pressure from other causes. The numbers are striking: the odds of atrial fibrillation were 5 times higher, nonfatal heart attack 2.6 times higher, heart failure 2.9 times higher, and coronary artery disease 1.9 times higher. Excess aldosterone appears to directly damage blood vessels and heart tissue independent of its effect on blood pressure, which is why identifying and treating it early matters so much.
How Aldosteronism Is Diagnosed
Screening starts with a blood test measuring the ratio of aldosterone to renin (a hormone the kidneys release to regulate blood pressure). In primary aldosteronism, aldosterone is high while renin is suppressed, because the body is trying to counteract the excess. Current guidelines recommend using an aldosterone-to-renin ratio (ARR) cutoff of 2.4 for people under 50 and 3.7 for those 50 and older, since the optimal threshold shifts with age.
A positive screening result doesn’t confirm the diagnosis on its own. A confirmatory test is needed, and one of the most common is the saline infusion test. You sit upright while receiving a slow intravenous saline drip over four hours. The idea is simple: flooding the body with salt water should suppress aldosterone in a healthy person. If your aldosterone level stays elevated above a defined threshold after the infusion, primary aldosteronism is confirmed.
Once confirmed, doctors need to determine whether the problem is in one adrenal gland or both, because that decision shapes the entire treatment plan. Imaging (typically a CT scan) and sometimes a specialized blood sampling procedure from the adrenal veins help pinpoint the source.
Treatment for a Single Adrenal Tumor
When the overproduction comes from a tumor on one adrenal gland, surgery to remove that gland is the standard approach. The procedure is usually done laparoscopically, meaning small incisions and a relatively short recovery. A meta-analysis of 43 studies covering roughly 4,000 patients found that about 51% achieved a complete cure of their hypertension after surgery, meaning normal blood pressure without any medications. The cure rate varied widely across studies, from 15% to 96%, depending on factors like how long a patient had hypertension before surgery and their age.
Even among the roughly half who aren’t fully cured, most see meaningful improvement. They typically need fewer medications and achieve better blood pressure control than before. Potassium levels almost always normalize after the affected gland is removed.
Treatment When Both Glands Are Overactive
If both adrenal glands are producing too much aldosterone (bilateral hyperplasia), surgery isn’t practical since you need at least some adrenal function. Instead, treatment relies on medications called mineralocorticoid receptor antagonists, which block aldosterone’s effects on the kidneys. Spironolactone is the most commonly used, typically started at 12.5 to 25 mg per day. Eplerenone is an alternative, often started at 25 mg once or twice daily, and tends to cause fewer hormonal side effects like breast tenderness in men.
For people with severe cases, particularly those with very low potassium, doctors may start at higher doses. The medication is usually adjusted over weeks based on blood pressure response and potassium levels. Most people stay on these medications long-term, and they’re effective at controlling both blood pressure and potassium when dosed correctly. Dietary sodium restriction also helps, since less sodium in the body means less raw material for aldosterone to work with.