Determination of Plasma Renin Concentration by Angiotensin I Immunoassay: Diagnostic Import of Precise Measurement of Subnormal Renin in Hyperaldosteronism

It is suggested that the prediction of a distinct APA can best be made in patients with hyperaldosteronism when the exact extent of renin suppression is taken into account and when DOCA is used to assess suppressibility of aldosterone.

Abstract

Radioimmunoassay of angiotensin I was applied to the estimation of renin concentration after incubation of human plasma with an excess of renin substrate from plasma of anephric sheep. With this method markedly subnormal plasma renin levels were accurately measured. The technique was used in the study of 18 patients with proven aldosterone-producing adenoma (APA), 5 with hyperaldosteronism associated with bilateral adrenal hyperplasia, and 23 with essential hypertension. Plasma renin concentration (PRC) was extremely low in APA, and a significantly higher mean basal level of PRC was seen in hyperplastic aldosteronism ( P It is suggested that the prediction of a distinct APA can best be made in patients with hyperaldosteronism when the exact extent of renin suppression is taken into account and when DOCA is used to assess suppressibility of aldosterone. While such evaluation may defer surgery in some patients with correctable hypertension, it may reduce the number with persistent hypertension after bilateral adrenalectomy.