Screening for primary aldosteronism

A serum potassium determination is usually recommended for new hypertensive patients as a screening test for primary aldosteronism and as a baseline for drug therapy. Since hypokalemia is not specific for aldosteronism, the authors assessed its use and limitations as a screening test in nine reported studies of 303 patients with aldosterone-producing adenomas (n=252) or adrenal hyperplasia (n=51). The optimal potassium cutoff level and the predictive ability of hypokalemia to detect aldosteronism were analyzed in a primary care setting with different diseases, test characteristics, and prevalences. Optimal screening for primary aldosteronism occurred at serum potassium <3.2 mEq/l in a primary care, low-prevalence population, and at higher potassium levels in higher-prevalence populations. Other screening tests, such as urinary aldoster-one levels and plasma renin activity, showed lower individual test performance characteristics, but when combined were similar in performance to serum potassium measurement. Received from the General Internal Medicine Division, Department of Medicine, Wright State University School of Medicine, Miami Valley Hospital, and Veteran’s Administration Medical Center, Dayton, Ohio. Dr. Snyder is presently a fellow in the Endocrinology Division, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina. Presented in part at the Seventh Annual Meeting of the Society for Research and Education in Primary Care Internal Medicine, Microcomputer Users Group, Washington, D.C., May 3, 1984.