Screening for primary aldosteronism without discontinuing hypertensive medications: Plasma aldosterone-renin ratio

The traditional workup for primary aldosteronism is cumbersome and requires discontinuing antihypertensive medications, which is inconvenient and pote ntially dangerous. A simple and accurate screening test that can be used wi thout modifying medications is needed. The plasma aldosterone-renin ratio ( ARR) is a valid screening assay for primary aldosteronism, but antihyperten sives are usually discontinued before obtaining this ratio, limiting its ut ility. The present prospective study is designed to examine the validity of the ARR as a screening test for primary aldosteronism if the ratio is meas ured 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 samp les in all 90 patients while maintaining their prescribed antihypertensive medications. Those with elevated ARRs (> 100 ng/dL + ng/mL/h) underwent fur ther diagnostic workup, including adrenal computed tomography and/or magnet ic resonance imaging and adrenal iodine 131 norcholesterol uptake scan. Fif teen patients (17%) had elevated ARRs greater than 100:1. Ten of 15 patient s 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 p atients responded to antialdosterone treatment. Thus, all 15 patients had g ood control of blood pressure after surgery and/or antialdosterone medicati ons. 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 medicati ons is not needed for this test. (C) 2001 by the National Kidney Foundation , Inc.