Verification of CRP measurement reagents in the laboratory according to ERM-DA474/IFCC

Abstract

The measurement of C-reactive protein (CRP) in serum is based on an immunological assay, and its standardization has been largely achieved by the serum protein reference material CRM470 (ERM-DA470) through the World Health Organization and the Japanese National Reference Material. Most of the reagents used for CRP measurement in Japan have been ERM-DA470 or ERM-DA472/IFCC as the primary reference material. However, the currently released lot is ERM-DA474/IFCC (DA474), and there are few reports of measuring reagents in accordance with DA474 in the laboratory. Here, we evaluated the basic performance of “LZ Test ‘Eiken’ CRP-RV”, a reagent for measuring CRP based on DA474. Accuracy, precision, analytical range, specificity, and reagent stability were assessed, and good results were obtained for all items. Compared with the control reagent, the correlation coefficient and regression equation showed good results, but a concentration-dependent sigmoidal error distribution was observed. This error was considered due to the difference of the linearity tendency of the calibration curve, including the precision in the low-concentration range, between the test reagent and the control. The high sensitivity of the test reagent is expected to contribute to the early detection of inflammatory reactions and latent diseases in clinical testing and to prompt therapeutic intervention.