Primary hyperaldosteronism (Conn's syndrome or aldosterone-producing adrenal tumor)
Is this unilateral or bilateral disease?
Once the diagnosis of primary hyperaldosteronismPrimary hyperaldosteronism - a disease where too much aldosterone is being made is confirmed, the next step is to figure out if the patient has unilateral disease (i.e. hyperactivity in one adrenal) or bilateral disease (i.e. hyperactivity in both adrenals) disease. The first step is to perform radiographic imaging looking for an aldosteroneAldosterone - a mineralocorticoid that controls blood pressure producing adenoma or tumor. Computed tomography (CAT) scan or magnetic resonance imaging (MRI) of the abdomen are the best imaging tests to look at the adrenal glands. If there is an adrenal tumor in one gland, especially if it is between 1 and 2 cm in size, there is a high chance that it is an aldosterone producing adenoma. Another test that may be done to help distinguish between unilateral and bilateral disease is the postural stimulation test. In this test, the patient's aldosterone and renin levels in the blood are measured while the patient is lying down and then again when standing up. Patients with an aldosterone producing adenoma will not have any increase in aldosterone levels after standing up. Patients with bilateral hyperplasia will have an increase in aldosterone levels after standing up. However, these tests are not 100% accurate. For example, some patients with primary hyperaldosteronism may have an unrelated adrenal tumor that is not producing too much aldosterone. The best test to differentiate unilateral versus bilateral disease is the adrenal venous sampling.
Adrenal Venous Sampling
Patients over 40 years of age and those without evidence of an adrenal tumor on imaging should also have a special test called adrenal venous sampling. This procedure is performed in the operating room and involves taking blood samples to measure the aldosteroneAldosterone - a mineralocorticoid that controls blood pressure levels directly from the adrenal glands by placing a catheter in the left and right adrenal veins. High hormoneHormone - a chemical made by a gland that travels in the bloodstream and "tells organs what to do." levels from one gland but not the other suggests unilateral disease. If the blood levels are the same on both sides, then the patient likely has bilateral disease. When performed by an experienced physician, adrenal venous sampling is very accurate at determining if the patient has unilateral or bilateral disease. Patients can usually go home the same day of the procedure.