Evaluation of serum cysteine-rich protein 61 and cystatin C levels for assessment of acute kidney injury after cardiac surgery

Objective The occurrence of acute kidney injury (AKI) after cardiopulmonary bypass (CPB) can lead to morbidity and mortality. We hypothesized that cysteine-rich protein 61 (CYR61) and cystatin C (CysC) may be potential novel biomarkers of AKI after cardiopulmonary bypass. Methods Patients were classified into AKI and non-AKI group depending on serum creatinine. Levels of creatinine, CysC, and CYR61 were measured at five time-points before and within 48h after the surgery. Results Fifty patients were included in the study. Serum creatinine pre-operative values were 74.0 +/- 43.3mol/L in AKI group vs. 64.8 +/- 17.9mol/L in non-AKI group. During 48h, the values increased to 124.6 +/- 67.2mol/L in AKI group (p<0.001) but in non-AKI group they did not change significantly. Serum CysC values were significantly increased already 2h after CBP in AKI group (949 +/- 557g/L, p<0.05) compared to non-AKI group (700 +/- 170g/L). Pre-operative serum CYR61 tended to be lower in AKI group (12.4g/L) than in non-AKI group (20.3g/L), but 24h after the surgery, the levels in AKI group tended to be higher than non-AKI group. Conclusion Serum CYR61 does not seem to be an early predictor of AKI in patients after cardiac surgery with CPB, but it might possibly identify patients at risk of developing more severe kidney injury. Serum CysC could be a promising biomarker of AKI, differentiating patients at risk of developing AKI after cardiac surgery as early as 2h after surgery.