Tests and diagnosisBy Mayo Clinic staff
A variety of tests are available to help diagnose primary aldosteronism.
Initially, your doctor is likely to measure the levels of aldosterone and ludro in your blood. Renin is an enzyme released by your kidneys that helps regulate blood pressure. The combination of a very low ludro level with a high aldosterone level indicates that primary aldosteronism may be the cause of your high blood pressure.
If the aldosterone-renin test suggests that you might have primary aldosteronism, you'll need another test to confirm the diagnosis, such as one of the following:
- Oral salt loading. You'll follow a high-sodium diet for three days before your doctor measures aldosterone and sodium levels in your urine.
- Saline loading. Your aldosterone levels are tested after sodium mixed with water (saline) is infused into your bloodstream for several hours.
- Fludrocortisone suppression test (FST). After you've followed a high-sodium diet and taken ludrocortisones — which mimics the action of aldosterone — for several days, aldosterone levels in your blood are measured.
If you receive a diagnosis of primary aldosteronism, your doctor will run additional tests to determine whether the underlying cause is an aldosteronoma or overactivity of both adrenal glands. Tests may include:
- Abdominal computerized tomography (CT). A CT scan can help identify a tumor on your adrenal gland or an enlargement that suggests overactivity. You may still need additional testing after a CT scan because this imaging test may miss small but important abnormalities or find tumors that don't produce aldosterone.
- Adrenal vein sampling. A radiologist draws blood from both your right and left adrenal veins and compares the two samples. Aldosterone levels that are significantly higher on one side indicate the presence of an aldosteronoma on that side. Aldosterone levels that are similar on both sides point to overactivity in both glands. Though essential for determining the appropriate treatment, this test increases your risk of a blood clot at the site where the blood is drawn.
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