title: Diagnostic value of the post-captopril test in primary aldosteronism.
abstract: Primary aldosteronism is a disorder with hypertension, hypokalemia, increased plasma aldosterone, and suppressed renin activity. A random plasma aldosterone/renin activity (PA/PRA) >65 (conventional units ratio [CUR] >30) has been proposed as a screening test. We have retrospectively determined the value of the post-captopril plasma aldosterone/renin activity (CAPT PA/PRA) test for the diagnosis of patients with primary aldosteronism whose PA/PRA was <65. We considered the CAPT PA/PRA test to be positive for primary aldosteronism if either the plasma aldosterone concentration did not drop below 0.33 nmol/L (12 ng/dL) or the ratio was >26 (CUR >12). We found 6 patients with a random PA/PRA of 21 to 60 (CUR 10 to 28), yet with an abnormal post-captopril test criteria for primary aldosteronism. Five had an abnormal saline suppression test, and all 6 were confirmed by a combination of diagnostic localization with computerized axial tomography, iodocholesterol scan, adrenal venous sampling, and/or surgery. Four had idiopathic adrenal hyperplasia, and 2 had an aldosterone-producing adenoma. One other patient had an abnormal random plasma aldosterone/renin activity ratio of 99 (CUR 46), a negative saline infusion study, and was determined to have essential hypertension. In summary, the CAPT PA/PRA, but not the random PA/PRA, correctly diagnosed 6 patients with primary aldosteronism in our institution. An additional patient with essential hypertension was incorrectly diagnosed as having primary aldosteronism by the PA/PRA test. We conclude that the simple addition of 25 mg of captopril, taken orally 2 hours before sampling, enhances the accuracy for diagnosing patients with primary aldosteronism.
authors.affiliation: Department of Medicine, University of Oklahoma, and Veterans Administration Medical Center, Oklahoma City, Okla, USA.
authors.forename: Oscar L
authors.initials: OL
authors.lastname: Castro
authors.forename: Xichun
authors.initials: X
authors.lastname: Yu
authors.forename: David C
authors.initials: DC
authors.lastname: Kem
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood; D002216:Captopril; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood; D012189:Retrospective Studies
chemical_list: D000450:Aldosterone; D002216:Captopril; D012083:Renin