Clinical evaluation of the renin-aldosterone system: Comparison of two methods in different clinical conditions

Abstract

Introduction: Measurement of plasma aldosterone/renin ratio is the key step in the diagnosis of primary aldosteronism. Aim: The aim of the authors was to analyze and compare the diagnostic utility of plasma aldosterone/renin activity and plasma aldosterone/renin concentration ratios. Methods: Plasma aldosterone and plasma renin activity were determined by radioimmunoassays and plasma renin concentration was measured by immunoradiometric assay in 134 subjects (80 women and 54 men, aged 46±15.5 years) including 49 healthy blood donors (control group), 59 patients with hypertension (25 treated and 34 untreated) and 26 patients with incidentally discovered adrenal adenomas. Results: There was a weak correlation (r = 0.59) between plasma renin activity and plasma renin concentration in the lower range (plasma renin activity, 0.63±0.41 ng/ml/h; plasma renin concentration, 8.1±4.9 ng/l). Considering the cut-off value of plasma aldosterone/renin ratios determined in controls (plasma aldosterone/renin activity ratio, 30 ng/dl/ng/ml/h; plasma aldosterone/renin concentration ratio, 3.0 ng/dl/ng/l), high proportion of falsely positive results were found among patients on beta-receptor blocker therapy (plasma aldosterone/renin activity ratio, 22.2%; plasma aldosterone/renin concentration ratio, 44.4%) Conclusion: The widely used plasma aldosterone/renin activity ratio can only be replaced with plasma aldosterone/renin concentration ratio with precaution on different clinical conditions. Orv. Hetil., 2012, 153, 1701–1710.