Diagnostic efficacy of chemiluminescence immunoassay versus radioimmunoassay in screening primary aldosteronism

Abstract

Objective To compare the sensitivity and specificity of chemiluminescence immunoassay (CLIA) and radioimmunoassay (RIA) in detection of aldosterone and renin, and to explore the optional detection methods and indicators for screening primary aldosteronism (PA). Methods A cross-sectional study was carried on 60 PA patients (with males accounting for 53.3% and at a median age of 50 years) diagnosed in our department from January to October 2018. Another baseline-matched 82 patients with essential hypertension (with males accounting for 50.0% and at a median age of 50 years) and 114 healthy controls (males accounting for 38.6% and at a median age of 46 years) at the same period were also recruited in this study. The plasma aldosterone concentration and renin concentration/renin activity were measured by CLIA and RIA respectively. The screening value of the 2 methods was evaluated by correlation analysis. Meanwhile, the plasma aldosterone concentration, plasma renin concentration (or activity), ratio of aldosterone/direct rennin concentration (ADRR), ratio of aldosterone/plasma rennin activity (ARR) and 2 combined indicators were measured by receiver operating characteristic (ROC) curve, to calculate sensitivity and specificity and determine the optimal cut-off point. Results There was a high correlation between plasma renin activity and direct renin concentration (r=0.880 4, P < 0.001), but the correlation between plasma aldosterone concentration measured by the 2 methods was not good (r=0.365 0, P < 0.001). The sensitivity of ADRR was the highest (91.53%) among all screening indices, and the specificity of diagnosis was significantly improved by combining plasma aldosterone concentration (CLIA, 96.49%). Among PA at an average age of 50 years, ADRR screening cut-off point was 12 (pg·mL-1)/(μU·mL-1), and ARR screening cut-off point was 20 (ng·dL-1)/(ng·mL-1·h-1). Conclusion CLIA is superior to RIA in detection of screening indices for PA. The diagnostic specificity of combined plasma aldosterone concentration (CLIA) and ADRR indices is the best.

Keywords

• primary hyperaldosteronism
• chemiluminescence immunoassay
• radioimmunoassay
• diagnosis