(See also Overview of the Adrenal Glands.)
In hyperaldosteronism, overproduction of aldosterone leads to fluid retention and increased blood pressure, weakness, and, rarely, periods of paralysis.
Hyperaldosteronism can be caused by a tumor in the adrenal gland or may be a response to some diseases.
High aldosterone levels can cause high blood pressure and low potassium levels. Low potassium levels may cause weakness, tingling, muscle spasms, and periods of temporary paralysis.
Doctors measure the levels of sodium, potassium, and aldosterone in the blood.
Sometimes, a tumor is removed, or people take drugs that block the action of aldosterone.
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) but mainly through the renin-angiotensin-aldosterone system (see Figure: 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 or primary hyperaldosteronism), although sometimes both glands are involved and are overactive. Sometimes hyperaldosteronism is a response to something else (a condition called secondary hyperaldosteronism), for example, certain diseases, such as very high blood pressure (hypertension) or narrowing of one of the arteries to the kidneys(.
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 then also measure renin and aldosterone levels. If the aldosterone level is 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 50 to 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 with corticosteroids for life. However, spironolactone or eplerenone can usually control the symptoms, and drugs for high blood pressure are readily available (see Table: Antihypertensive Drugs). Spironolactone can often cause breast enlargement (gynecomastia), decreased sex drive, and erectile dysfunction in men by blocking the effects of testosterone.
Rarely do both adrenal glands have to be removed.