Screening for Primary Aldosteronism Without Discontinuing Hypertensive Medications

The traditional workup for primary aldosteronism is cumbersome and requires discontinuing antihypertensive medications, which is inconvenient and potentially dangerous. A simple and accurate screening test that can be used without modifying medications is needed. The plasma aldosterone-renin ratio (ARR) is a valid screening assay for primary aldosteronism, but antihypertensives are usually discontinued before obtaining this ratio, limiting its utility. The present prospective study is designed to examine the validity of the ARR as a screening test for primary aldosteronism if the ratio is measured randomly while patients continue antihypertensive therapy. During the 18-month study period, 90 patients were referred to the hypertension clinic with poorly controlled hypertension. ARR was measured in random blood samples in all 90 patients while maintaining their prescribed antihypertensive medications. Those with elevated ARRs (100 ng/dL ng/mL/h) underwent further diagnostic workup, including adrenal computed tomography and/or magnetic resonance imaging and adrenal iodine 131 norcholesterol uptake scan. Fifteen patients (17%) had elevated ARRs greater than 100:1. Ten of 15 patients were found to have adrenal adenoma on diagnostic workup, and adenoma was later confirmed by histological examination after surgical removal in these 10 patients. Five patients were found to have adrenal hyperplasia; all 5 patients responded to antialdosterone treatment. Thus, all 15 patients had good control of blood pressure after surgery and/or antialdosterone medications. No patient showed a falsely elevated ARR. Data suggest that the ARR is a valid screening assay for primary aldosteronism in patients with poorly controlled blood pressure, and discontinuation of antihypertensive medications is not needed for this test. Editorial Comment: The authors screened 90 patients with hypertension and a plasma aldosterone-to-renin ratio and found 15 who had values that exceeded 100:1. Of these 15 patients 10 had adenomas confirmed surgically and the remainder had hyperplasia that responded to spiranolactone therapy. If this percentage is representative, then 16% of hypertensive patients have primary aldosteronism rather than the accepted incidence of 0.5%, which is a significant observation with great therapeutic implications. However, those that had ratios less than 100:1 were not evaluated so the number of false-negatives is not known. However, 100% specificity for ratios greater than 100:1 is certainly remarkable. The beauty of this test is that it can be performed without altering any of the patient’s medications, that is it can be obtained randomly. If these findings are confirmed, then we will have come full circle since Conn originally purported that most patients with hypertension have primary aldosteronism. W. Scott McDougal, M.D.