A dual-label time-resolved fluorescence immunoassay for the simultaneous determination of cystatin C and beta(2)-microglobulin in urine

Background: Contrast media is widely used in clinical diagnostic and interventional procedures, but may cause damage to the kidney, that is, contrast-induced nephropathy. This study was to establish a dual-label time-resolved fluorescence immunoassay (TRFIA) for the simultaneous determination of renal function markers cystatin-C (Cys-C) and beta(2)-microglobulin (beta(2)-MG) for the early diagnosis and follow-up surveillance of contrast-induced nephropathy. Methods: A sandwich immunoassaywas used to detect the concentration of Cys-C, and the competitive immunoassay was used to detect the concentration of beta(2)-MG in 50 samples of urine. The performance of this dual-label TRFIA was evaluated and compared with commercial assays. Results: The sensitivity for Cys-C detection was 1.26 ng/ml, the average recovery was 99.36%; The sensitivity for beta(2)-MG detection was 2.13 ng/ml, the average recovery was 100.18%. Bland-Altman analysis showed that the dual-label TRFIA method and the commercial kits had a good agreement, suggesting they can be used interchangeably in clinical urine analysis. Conclusion: The present dual-label TRFIA has high sensitivity, specificity and accuracy in clinical sample analysis. This method can be used for the early diagnosis and follow-up surveillance of the contrast-induced nephropathy.