Primary Hyperaldosteronism (Conn's Syndrome)

Adrenal adenoma on CTAldosterone helps control blood pressure by holding onto salt and losing potassium from the blood. The increased salt increases the blood pressure. Hyperaldosteronism is a disease in which the adrenal gland(s) make too much aldosterone which leads to hypertension (high blood pressure) and low blood potassium levels.

Primary hyperaldosteronism can be caused by either hyperactivity in one adrenal gland (unilateral disease) or both (bilateral disease). Unilateral disease is usually caused by an aldosterone producing adenoma (benign tumor) and less commonly by adrenal cancer or hyperplasia (when the whole gland is hyperactive). Bilateral disease is usually caused by bilateral hyperplasia (when both glands are hyperactive). There are rare genetic syndromes like familial hyperaldosteronism type I and II which may cause both glands to be hyperactive.

Signs and Symptoms

High blood pressure is often the only sign of hyperaldosteronism. The hypertension is usually hard to control and patients are often on 4 or more blood pressure medications. The hypertension may cause headaches, blurred vision, and dizziness. While patients with hyperaldosteronism may have normal potassium levels, many patients may have low potassium levels. The hypokalemia (low potassium level) can cause symptoms like fatigue, numbness, increased urination, increased thirst, muscle cramps, and muscle weakness. Hyperaldosteronism leads to an increased risk for heart attacks, heart failure, strokes, kidney failure, and early death.


Primary hyperaldosteronism is diagnosed by measuring the blood levels of aldosterone and renin (a hormone made by the kidney). To best measure these hormones, blood samples should be drawn in the morning. In primary hyperaldosteronism, the aldosterone level will be high while renin will be low or undetectable. The potassium level may be low or normal. If these tests are positive, then patients may have another test to confirm the diagnosis. These tests try to lower the amount of aldosterone produced either by giving a medication or giving extra salt through the diet or an intravenous fluid. If the aldosterone level is high and the renin level is low after these tests, the diagnosis is confirmed. Some medications, especially blood pressure medications, can interfere with these tests. Your physician will review your medications and decide if any need to be stopped for 4 to 6 weeks prior to testing. In general, patients with a long-standing history of hypertension or difficult to control hypertension should be screened for hyperaldosteronism.

  • PAC:PRA ratio

    This blood test is a screening test, meaning that it is performed if hyperaldosteronism is suspected but not yet diagnosed. A high ratio of PAC to PRA suggests primary hyperaldosteronism, but additional testing may be needed to confirm the diagnosis.

  • Captopril Suppression Test

    This blood test measures the body's response to captopril, a medication used to treat high blood pressure. Results of this test can confirm whether a person has primary hyperaldosteronism.

  • 24-hour Urinary Excretion of Aldosterone Test

    Patients eat a high-salt diet for five days, and then undergo urine tests during a 24-hour period. If the level of aldosterone in the urine is high, such results can confirm that a patient has primary hyperaldosteronism.

  • Saline Suppression Test

    In this test, the patient receives a salt solution through an IV. A blood test then measures the patient's levels of aldosterone and renin. Primary hyperaldosteronism can be confirmed if the level of aldosterone in the blood remains high and renin is low after this salt loading.


Dr. Morrissey demonstrates the catheter used in Adrenal Venous Sampling. Click here to see the full article.For patients with proven primary hyperaldosteronism, the next step is to figure out if this is unilateral or bilateral disease. This is critical because the treatment for each is different. A computed tomography (CT or CAT) scan or magnetic resonance imaging (MRI) scan will be done to see if there is a tumor in either adrenal gland. If the patient is younger than 40 years old and there is a tumor in only one adrenal (especially if it is between 1 and 2 cm), then the patient may go directly to treatment. If the patient is older than 40 and/or there is either no tumor seen or tumors in both adrenals, then the patient will have a special test called selective venous sampling. In this test, a surgeon or radiologist will draw blood directly from the veins draining both adrenal glands to determine if one or both are making too much hormone. Significantly higher hormone levels on one side only clinches the diagnosis of unilateral disease. Selective venous sampling is usually done as an outpatient procedure.


The treatment for hyperaldosteronism depends on the underlying cause. In patients with a single benign tumor (adenoma), surgical removal (adrenalectomy) is curative. This operation is usually performed laparoscopically, through several very small incisions. (See Adrenal Surgery) After successful adrenalectomy, approximately 95% of patients notice significant improvement in their hypertension. Of this 95%, one third are cured of high blood pressure and the rest are on fewer medications or lower dosages. For patients with bilateral hyperplasia, the best treatment is a medication called an aldosterone-antagonist (spironolactone, eplerenone) which blocks the effect of aldosterone. In addition, patients are maintained on a low salt diet.

Without proper treatment, patients with hyperaldosteronism often suffer from poorly controlled high blood pressure and are at increased risk for heart attacks, heart failure, strokes, kidney failure, and early death. However, with appropriate treatment, this disease is treatable and has an excellent prognosis. Patients with difficult to control or long-standing hypertension should be screened for primary hyperaldosteronism.

Next Steps

If you are dealing with an adrenal issue, our team at the Columbia Adrenal Center is here to help. Call (212) 305-0444 or request an appointment online.