CHE-39 : The Evaluation of a Newly Developed Rapid Assay for Plasma Activated Renin Concentration (ARC) using the CLEIA Method

Objective: Renin is a proteolytic enzyme involved in blood pressure regulation and water/electrolyte metabolism, and the evaluation of plasma renin activity (PRA) is important in the clinical diagnosis of hypertensive patients. However, renin is an unstable substance. A plasma activated renin concentration (ARC) assay using the CLEIA method was recently developed. We herein evaluate the basic performance of the assay, and compare the ARC and PRA values. Materials and Methods: The “Accuraseed® Renin” kit, with an Accuraseed® Automatic CLEIA analyzer (WAKO fine chemical, Tokyo, Japan) was used to evaluate the ARC. The PRA was measured with a Plasma Renin Activity “FR” kit (Fujirebio Inc., Japan). The correlation between the ARC and PRA values was investigated using frozen patient plasma that had separated less than 1 hour after blood collection. Results: In the basic evaluation of the ARC assay, the reproducibility within and between the runs for low and high control materials was CV 2.85%, 3.23% (3.62 pg/ mL), and CV 1.78%, 1.78% (52.6 pg/mL), respectively. The dilution linearity was confirmed up to 402 pg/mL, and the minimum detection sensitivity was 0.2 pg/mL. In the study of the sample stability, ARC values decreased an average of 2.8% (0.0-7.7%) when plasma was stored at room temperature for 4 hours, and were reduced by an average of 8.7% (4.9-13.6%) at 18 hours. The correlation between the ARC (y) and PRA (x) values was y = 6.41 x + 0.03, and correlation coefficient r = 0.97 (n=20); however, 2 of the samples showed discrepancies. Conclusion: The basic performance of the newly developed ARC assay method was good, and a good correlation with PRA was recognized. The measured PRA values are often influenced by pre-analytical factors during sampling/handling; thus, the ARC assay that can be performed quickly in the hospital is considered to be useful for clinical application.