Measurement of plasma aldosterone and renin concentration, or activity, is useful for selecting antihypertensive agents as well as detecting hyperaldosteronism in hypertensive patients. However, it takes several days to get results when measured by radioimmunoassay and development of more rapid assays has been long expected. We have developed chemiluminescent enzyme immunoassays enabling the simultaneous measurement of both aldosterone and renin concentrations in ten-minutes by a fully automated assay using antibody-immobilized magnetic particles with quick aggregation and dispersion. We performed clinical validation of diagnostic ability of this newly developed assay-based screening of 125 patients with primary aldosteronism from 97 patients with essential hypertension. Results of this novel assay significantly correlated with the results of radioimmunoassay (aldosterone, active renin concentration and renin activity) and liquid chromatography-tandem mass spectrometry (aldosterone). The analytical sensitivity of this particularly novel active renin assay was 0.1 pg/ml, which was better than that of radioimmunoassay (2.0 pg/ml). Using Bland-Altman plots with the mass-spectrometry values, both bias and limits of agreement with 95% confidence interval of the automated aldosterone assay were smaller than those of the radioimmunoassay, indicating smaller systemic errors in the novel measurement. The ratio of aldosterone-over-renin concentrations of 11.2 (ng/dl per pg/ml) provided 80.8% sensitivity and 94.9% specificity as a cut-off for differentiating primary aldosteronism from essential hypertension. This novel measurement is expected to be a clinically reliable alternative for conventional radioimmunoassay and to provide better throughput and cost-effectiveness in diagnosis of hyperaldosteronism from larger numbers of hypertensive patients in clinical settings.
20 - 23 May 2017
European Society of Endocrinology