Evaluation of Primary Aldosteronism

What is primary hyperaldosteronism?

Aldosterone is a hormone made by the adrenal gland that primarily helps control blood pressure. When blood pressure is low, aldosterone tells the kidneys to hold onto sodium and water and get rid of potassium. Too much aldosterone increases the amount of fluid in the body (raising your blood pressure) and lowers the potassium to potentially unsafe levels. Primary hyperaldosteronism is a disorder in which one or both adrenal glands make too much aldosterone.

The word “primary” means that the problem is caused by the adrenal gland(s) directly. The two most common causes of primary hyperaldosteronism are 1) a single adrenal tumor that makes aldosterone (aldosteronoma) and 2) enlargement/hyperactivity of both adrenal glands (bilateral adrenal hyperplasia). Less common causes of primary hyperaldosteronism include one-sided (unilateral) adrenal hyperplasia, cancerous adrenal tumors, and genetic syndromes such as familial hyperaldosteronism.

Signs and Symptoms

The most common sign of primary hyperaldosteronism is high blood pressure that does not respond to standard blood pressure medications or takes more blood pressure medications that normal to lower the blood pressure. People with high blood pressure that is difficult to control with multiple medications should be tested for primary hyperaldosteronism. A low level of potassium in the blood is another sign, although normal potassium levels may still be seen with primary hyperaldosteronism. The symptoms of primary hyperaldosteronism are caused by the blood pressure and low potassium. High blood pressure may cause headache or blurred vision. Low potassium may cause fatigue, muscle cramps, muscle weakness, numbness, or temporary paralysis.

Diagnosis

The best screening tests to determine if you have primary hyperaldosteronism are simple blood tests that measure the levels of potassium, aldosterone, and renin in the blood. People with primary hyperaldosteronism will classically have high aldosterone levels and very low renin levels. They will often also have low potassium levels. If the screening tests suggest primary hyperaldosteronism, then additional testing may be performed to confirm the diagnosis. These tests involve trying to lower the amount of aldosterone that is being made by your body. If aldosterone remains high and renin remains low despite the intervention/test, the diagnosis is confirmed. It is important to note that certain high blood pressure medications may interfere with the these tests and thus, after consultation with a physician, should be stopped 4 to 6 weeks prior to testing.

Once the diagnosis of primary hyperaldosteronism is made, the next step is to figure out if the disease is due to an abnormality in one or both adrenal glands. Computed tomography (CAT) scan or magnetic resonance imaging (MRI) are the best imaging tests to look at the adrenal glands. If there is an adrenal tumor in one gland, especially if it is between 1 and 2 cm in size, there is a high chance that it is an isolated aldosterone-producing adrenal tumor (aldosteronoma). However, these tests are not 100% accurate, as some people with primary hyperaldosteronism may have an unrelated adrenal tumor that is not producing too much aldosterone.