In hyperaldosteronism, overproduction of aldosterone leads to fluid retention and increased blood pressure, weakness, and, rarely, periods of paralysis.
Aldosterone, a hormone produced and secreted by the adrenal glands, signals the kidneys to retain more sodium and excrete more potassium. Aldosterone production is regulated partly by corticotropin (secreted by the pituitary gland) and partly through the renin-angiotensin-aldosterone system (see see Regulating Blood Pressure: The Renin-Angiotensin-Aldosterone System). Renin, an enzyme produced in the kidneys, controls the activation of the hormone angiotensin, which stimulates the adrenal glands to produce aldosterone.
Hyperaldosteronism can be caused by a tumor (usually a noncancerous adenoma) in the adrenal gland (a condition called Conn syndrome), although sometimes both glands are involved and are overactive. Sometimes hyperaldosteronism is a response to certain diseases, such as very high blood pressure (hypertension) or narrowing of one of the arteries to the kidneys.
Symptoms and Diagnosis
High aldosterone levels can lead to low potassium levels. Low potassium levels often cause no symptoms but may lead to weakness, tingling, muscle spasms, and periods of temporary paralysis. Some people become extremely thirsty and urinate frequently.
Doctors who suspect hyperaldosteronism first test the levels of sodium and potassium in the blood. Doctors may also measure aldosterone levels. If they are high, spironolactone or eplerenone, drugs that block the action of aldosterone, may be given to see if the levels of sodium and potassium return to normal. Doctors also measure the levels of renin. In Conn syndrome, the levels of renin are also very low.
When too much aldosterone is being produced, doctors examine the adrenal glands for a noncancerous tumor (adenoma). Computed tomography (CT) or magnetic resonance imaging (MRI) can be helpful, but sometimes blood samples from each of the adrenal glands must be tested to determine the source of the hormone.
If a tumor is found, it can usually be surgically removed. When the tumor is removed, blood pressure returns to normal, and other symptoms disappear about 70% of the time. If no tumor is found and both glands are overactive, partial removal of the adrenal glands may not control high blood pressure, and complete removal will cause Addison disease, requiring treatment for life. However, spironolactone or eplerenone can usually control the symptoms, and drugs for high blood pressure are readily available. Rarely do both adrenal glands have to be removed.
Last full review/revision September 2012 by Ashley B. Grossman, MD, FRCP, FMedSci