Conn's Syndrome

What is Conn’s syndrome?

Conn’s syndrome is the most common cause of secondary hypertension. It is a condition characterized by excessive secretion of aldosterone from the adrenal glands. The adrenal glands are small triangular organs located on the top of the kidneys. They are part of the endocrine system, a group of glands that produce and secrete hormones that act on and regulate many systems throughout the body. Aldosterone is produced by the outer layer of the adrenal glands, the cortex. It is a hormone that plays an important role in maintaining blood volume, pressure, and electrolyte balance. Its production is normally regulated by renin, an enzyme produced in the kidneys. When renin increases, due to low blood pressure, decreased blood flow to the kidneys or to a sodium deficiency, aldosterone increases; when renin decreases, aldosterone decreases.

With Conn’s syndrome, which is also referred to as primary hyperaldosteronism, excessive aldosterone is produced by one or more benign adrenal tumors, by hyperplasia, for unknown reasons (idiopathic), or rarely, by a cancerous adrenal tumor.

Regardless of the cause, increased aldosterone can lead to hypokalemia, increased blood pH (alkalosis), hypertension and, rarely, to hypernatremia. It may cause few and nonspecific symptoms. Those with significant hypokalemia and/or hypertension may have symptoms that include: frequent urination, increased thirst, weakness, fatigue, temporary paralysis, palpitations, headaches, muscle cramps, and tingling.

Diagnosing Conn’s syndrome is important because it represents one of the few causes of hypertension that is potentially curable. Although anyone can get primary hyperaldosteronism, it commonly occurs in adults between the ages of 30 and 50 and is more common in women than men. The presence of hypokalemia in a person with hypertension suggests the need to look for primary hyperaldosteronism.

Suspicion of Conn’s syndrome may be raised in patients who are resistant to standard hypertension therapies.

Secondary aldosteronism must be distinguished from primary aldosteronism. It is not considered Conn’s syndrome and can occur as a result of anything that increases renin levels, such as decreased blood flow to the kidneys, low blood pressure, or low sodium levels in the urine. The most important cause is narrowing of the blood vessels that supply the kidney, termed renal artery stenosis. Other causes of secondary hyperaldosteronism include congestive heart failure, cirrhosis, kidney disease, and toxemia of pregnancy.