Diagnosis

If your doctor suspects primary aldosteronism, you'll likely have a test to measure levels of aldosterone and renin in your blood. Renin is an enzyme released by your kidneys that helps control blood pressure. If your renin level is very low and your aldosterone level is high, you may have primary aldosteronism.

Additional tests

If the aldosterone-renin test suggests primary aldosteronism, you'll need other tests to confirm the diagnosis and look for potential causes. Possible tests include:

• Salt-loading test. There are a few ways to do this blood or urine test. You may eat a high-sodium diet for a few days or you could have a saline infusion for several hours before your doctor measures your aldosterone levels. You may also be given fludrocortisone — a drug that mimics the action of aldosterone — in addition to the high-sodium diet before the test.
• Abdominal CT scan. A CT scan may find a tumor on your adrenal gland or show an enlarged adrenal gland that suggests the gland is overactive.

• Adrenal vein blood test. A radiologist draws blood from both your right and left adrenal veins and compares the two samples. If only one side has elevated aldosterone, your doctor may suspect a growth on that adrenal gland.

  This test involves placing a tube in a vein in your groin and threading it up to the adrenal veins. Though essential for determining the appropriate treatment, this test carries the risk of bleeding or a blood clot in the vein.