The results showed that serum Cys-C, RBP4, and NGAL were significantly higher in the AKI group compared with the healthy group (P < 0.05), and the mean concentrations of the three serum markers increased as the severity of the disease increased, while correlation analysis showed that all three serum markers were positively correlated with serum Scr levels (P < 0.001). Here, RBP4 is linked to acute kidney injury.