Comparisons of plasma aldosterone and renin data between an automated chemiluminescent immunoanalyzer and conventional radioimmunoassays in the screening and diagnosis of primary aldosteronism.

Determining values of plasma renin activity (PRA) or plasma active renin concentration (ARC), plasma aldosterone concentration (PAC), and aldosterone-to-renin ratio (ARR) is essential to diagnose primary aldosteronism (PA), but it takes several days with conventional radioimmunoassays (RIAs). Chemiluminescent enzyme immunoassays for PAC and ARC using the Accuraseed® immunoanalyzer facilitated the determination, but relations between Accuraseed® immunoanalyzer-based and RIA-based values in samples of PA confirmatory tests and adrenal venous sampling remained to be elucidated. We addressed this issue in the present study. This is a prospective, cross-sectional study. ARC and PAC values were measured by the Accuraseed® immunoanalyzer in samples, in which PRA and PAC values had been measured by the PRA-FR® RIA and SPAC®-S Aldosterone kits, respectively. The relations between Accuraseed® immunoanalyzer-based and RIA-based values were investigated with regression analyses. The optimal cutoff of Accuraseed® immunoanalyzer-based ARR for PA screening was determined by the receiver operating characteristic analysis. After log-log transformations, linear relations with high coefficients of determination were observed between Accuraseed® immunoanalyzer-based and RIA-based data of renin and aldosterone. Following the PA guidelines of Japan Endocrine Society, Accuraseed® immunoanalyzer-based cutoffs were calculated from the regression equations: the basal PAC for PA screening >12 ng/dL, PAC for the saline infusion test >8.2 ng/dL, ARC for the furosemide-upright test <15 pg/mL, and ARR for the captopril challenge test >3.09 ng/dL per pg/mL. The optimal cutoff of Accuraseed® immunoanalyzer-based ARR for PA screening was >2.43 ng/dL over pg/mL not to overlook bilateral PA patients. The present study provided conversion formulas between Accuraseed® immunoanalyzer-based and RIA-based values of renin, aldosterone, and ARR, not only in basal samples but also in samples of PA confirmatory tests and adrenal venous sampling. Although validation studies are awaited, the present study will become priming water of harmonization of renin and aldosterone immunoassays.
Competing Interests: FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan (http://ffwk.fujifilm.co.jp) provided the authors an Accuraseed® automated chemiluminescent enzyme immunoanalyzer, and Accuraseed® Aldosterone and Accuraseed® Renin kits to perform this study. The company did not provide the authors grants, royalties or licenses, consulting fees, payment or honoraria, support for attending meeting and/or travel, or stock or stock options. There are no patents planned, issued, or pending in relation to this study. The company had no role in the study design; collection, analysis, and interpretation of data; writing of the paper; and/or decision to submit for publication. This does not alter our adherence to PLOS ONE policies on sharing data and materials. Sharing the data of the present study is restricted by the Shizuoka General Hospital Research Ethical Committee following the Ethical Guidelines for Medical and Health Research Involving Human Subjects in Japan as described in the Data Availability statement. The de-identified dataset of this study is available on request to Shizuoka General Hospital Research Ethical Committee, Email: chiken-sougou@shizuoka-pho.jp. All requests must include an analysis plan and the plan must be approved by this ethics committee. Except as described above, none of the authors have any competing interests associated with this research.