Adrenal Disorders Hyperaldosteronism (Conn's Syndrome)

Hyperaldosteronism is a disease in which the adrenal glands produce excess aldosterone, which leads to high blood pressure (hypertension), low blood potassium levels, and retained salt. Increased aldosterone can result from a benign tumor of one adrenal gland, which is called an adenoma, or an enlargement of both adrenal glands, called bilateral hyperplasia. The underlying causes of these conditions are not known.

Diagnosis

High blood pressure is often the only clinical sign of hyperaldosteronism. Some patients may also have increased excretion of potassium in the urine, which can lead to voiding large amounts of urine, especially at night. The resulting decrease in the level of potassium in the blood leads to fatigue and muscle weakness. However, all of these symptoms overlap with other, more common conditions such as diabetes mellitus. Many patients with hyperaldosteronism will not have a low blood potassium level.

Hyperaldosteronism is diagnosed by measuring the blood levels of aldosterone and renin, a hormone made by the kidney that stimulates the adrenal glands to produce aldosterone. To best measure these hormones, blood samples need to be drawn in the morning after the patient has been lying flat for 30 minutes. In patients with this condition, the aldosterone level will be elevated in the setting of a low or undetectable renin level.

Patients will also undergo special scanning to determine if one or both glands are enlarged. In some cases, patients will need blood drawn directly from the veins draining both adrenal glands to determine which one is overproducing the hormone, a test called selective venous sampling.

Treatment

The treatment for hyperaldosteronism depends on the underlying cause. In patients with a single benign tumor (adenoma), surgical removal (adrenalectomy) is curative. This is usually performed laparoscopically, through several very small incisions. For patients with hyperplasia of both glands, successful treatment is often achieved with spironolactone or eplerenone, drugs that block the effect of aldosterone.

In the absence of proper treatment, individuals with hyperaldosteronism often suffer from poorly controlled high blood pressure, which may be associated with increased rates of stroke, heart disease, and kidney failure. With appropriate treatment, the prognosis is excellent.