An aldosteronoma is a noncancerous tumor that forms in the hormone-producing adrenal glands, which sit on top of the kidneys. The tumor produces and secretes higher-than-normal amounts of aldosterone, a hormone that plays an important role in regulating blood pressure.

Aldosteronomas are one of the main causes of primary hyperaldosteronism, a condition in which one or both adrenal glands release too much aldosterone into the blood, resulting in high blood pressure, and in some cases, low levels of potassium. Primary hyperaldosteronism is the most common cause of secondary hypertension (i.e., high blood pressure caused by another condition) in the U.S.

It is estimated that aldosteronomas cause around 30% of cases of primary hyperaldosteronism, while roughly 60% are caused by bilateral adrenal hyperplasia (i.e., enlarged adrenal glands that produce and secrete excessive aldosterone). In rare cases, unilateral adrenal hyperplasia (2%) or adrenocortical carcinoma (< 1%) can be the cause. Primary hyperaldosteronism is most commonly diagnosed in people between the ages of 30 and 50; aldosteronomas are very rare in children.

People with an aldosteronoma can experience a range of symptoms, including headaches, muscle weakness, spasms, and fatigue. In very severe cases, a person may experience sporadic temporary paralysis due to severely low blood potassium levels. Without treatment, the condition can lead to serious heart problems, including atrial fibrillation and heart attack, among others.

Fortunately, effective treatments are available for aldosteronomas, including surgery and medications. In many cases, patients can either be completely cured with surgery, or have a significant reduction in their blood pressure medication requirements.

The adrenals are small, hormone-producing glands located on top of the kidneys. They produce a number of different hormones, including aldosterone. When aldosterone is secreted, it directs the kidneys to increase the salt and water levels in the blood, resulting in elevated blood volume and blood pressure. Aldosterone also directs the body to excrete potassium during urination.

Normally, the body carefully controls the production of aldosterone, ensuring that levels don’t get too high or low. This helps keep blood pressure and potassium levels within normal ranges.

In an individual with an aldosteronoma, the mechanisms the body uses to regulate aldosterone production don’t work, leading to an over-production of aldosterone (known as Conn syndrome).

People with primary hyperaldosteronism have high blood pressure and may also have low levels of potassium in their blood in up to 30% of cases. While high blood pressure usually doesn’t cause symptoms on its own, people with low potassium levels often have muscle weakness, fatigue, and increased urination, among other symptoms.

People with an aldosteronoma are also at increased risk of cardiovascular problems, including heart arrhythmias, such as atrial fibrillation, heart attack, heart failure, and stroke. Kidney failure can also occur if high blood pressure is not controlled.

An aldosteronoma is caused by a genetic change, or mutation. Most of these genetic changes occur during a person’s lifetime and are not passed from parents to a child.

People with an aldosteronoma typically have high blood pressure, but most don’t have any other symptoms.

When low potassium levels result, however, people may experience one or more of the following symptoms related to their aldosteronoma:

• Muscle weakness or, rarely, episodes of muscle paralysis
• Muscle spasms and/or cramps
• Fatigue
• Headache
• Excessive thirst
• Excessive or frequent urination
• Waking up at night to urinate
• Numbness and/or tingling of hands and feet

To diagnosis an aldosteronoma, your doctor will review your medical history, conduct a physical exam, and order one or more diagnostic tests.

The first step in making a diagnosis is to determine if you have primary aldosteronism. You should tell your doctor when you started experiencing symptoms. You may also be asked whether you have any risk factors for primary hyperaldosteronism, including whether you have a family history of the condition, high blood pressure, or have had a hemorrhagic stroke before age 40. During a physical exam, your doctor will check your blood pressure and look for signs and symptoms of low potassium levels, including muscle weakness and irregular heart rate.

Even if you don’t have symptoms, you may be given a blood test to screen for the condition if you meet any of the following criteria:

• Sustained high blood pressure
• High blood pressure and low potassium levels
• High blood pressure that doesn’t improve with medications
• High blood pressure and sleep apnea
• High blood pressure with an adrenal incidentaloma (an adrenal tumor that has been found incidentally, during an imaging test done for another medical problem)
• High blood pressure and a family history of primary hyperaldosteronism, early-onset high blood pressure, or stroke before age 40

Blood and urine tests are used to diagnose primary aldosteronism—they measure the levels of sodium, potassium, aldosterone, and other substances in your blood and urine. They cannot, however, determine whether the condition is caused by an aldosteronoma or adrenal hyperplasia.

To determine if an aldosteronoma is present, you doctor may order a computed tomography (CT) scan of the adrenal glands. If the CT scan shows the presence of a mass in one or both adrenal glands and you’re considering surgery to treat the condition, an additional test called adrenal vein sampling (AVS) may be necessary. In this test, blood is collected from veins of the left and right adrenal glands. The level of aldosterone is then measured to determine if one or both of the adrenal glands is producing excessive levels of aldosterone.

An aldosteronoma is treated by endocrine surgeons and endocrinologists who specialize in the treatment of adrenal disorders and other endocrine conditions. Treatments for aldosteronomas include:

• Surgery. If only one adrenal gland is affected, adrenalectomy, the surgical removal of the affected adrenal gland, is the first-line treatment for an aldosteronoma. In some cases, the surgeon may remove only part of the affected adrenal gland. In most cases, adrenalectomies are done using a minimally invasive surgical technique. In these procedures, the surgeon makes three or four small incisions, either on the abdomen or the back, then inserts a laparoscope—a thin tube equipped with a camera and light—into the incisions. The laparoscope allows the surgeon to examine and remove the adrenal gland.
  
  Adrenalectomy improves blood pressure and returns potassium levels to normal in nearly all patients. In about 30% of cases, adrenalectomy also cures high blood pressure completely. Most people, however, will need to take some medications to control blood pressure even after having the affected adrenal gland removed.
  
  After surgery, patients should see their doctor regularly to monitor their blood pressure and potassium levels and to determine the appropriate doses of any necessary medications
  
  
• Medications. For people who cannot or do not want to undergo adrenalectomy—and for those who have hyperplasia of both adrenal glands—medications can help control blood pressure and normalize potassium levels. Before undergoing surgery, people may also need to take these medications to control their blood pressure and potassium levels.
  • Aldosterone receptor antagonists. These drugs cause the body to excrete excess salt and water, though not potassium, during urination. This helps lower blood pressure and increase potassium levels.
  • Potassium-sparing diuretics. These may be used to help lower blood pressure in people who do not tolerate aldosterone receptor antagonists. Diuretics, or water pills, work by increasing the amount of water and salt that gets excreted during urination. Potassium-sparing diuretics increase urination without potassium loss.

If left untreated, an aldosteronoma may increase the risk for certain complications, including:

• Stroke
• Heart attack
• Atrial fibrillation
• Heart failure
• Diabetes
• Chronic kidney disease
• Metabolic syndrome (also known as insulin resistance syndrome)
• Obstructive sleep apnea

With early treatment, the outlook for people with an aldosteronoma is good. Treatments are available that can help normalize blood pressure and potassium levels. Surgical removal of the affected adrenal gland improves blood pressure and potassium levels for the vast majority of patients. In many cases, it can cure the high blood pressure that was caused by the aldosteronoma. Medications can also help control the condition as well.

“The Smilow Endocrine Neoplasia Center at Yale specializes in the diagnosis and treatment of primary hyperaldosteronism caused by aldosteronomas and hyperplasia,” says Smilow Cancer Hospital endocrine surgeon Courtney Gibson, MD. “A multidisciplinary team of experts in medical endocrinology, endocrine surgical oncology, and interventional radiology work diligently to provide comprehensive and compassionate care to patients suffering from this condition. This is particularly important because many patients have suffered from severe hypertension caused by this condition for many years due to a missed diagnosis of the condition.”