To the Editor.
—A variety of tests have been developed to help diagnose aldosterone-producing adenoma (APA) and distinguish it from idiopathic hyperaldosteronism (IHA). Recently, in the November Archives (1981;141: 1589-1593), Hiramatsu et al described a simple screening test to identify APA, which is based on a high plasma aldosterone to plasma renin activity (A-PRA) ratio and is claimed to be unaffected by various antihypertensive drug regimens. Unfortunately, the authors had no patients with IHA for comparison, and they gave no clinical details about the 11 patients who, despite high A-PRA ratios, did not have APA.We tested a number of screening methods on a 51-year-old man with IHA, including the one proposed by Hiramatsu et al. This patient had had hypertension for 15 years, and, sincefirst seen in our clinic six years ago, his serum potassium level had been consistently less than 2.9 mEq/L, except when treated with spironolactone. The Table shows the patient's