Multivariable logistic regression analysis showed that preoperative Hb (OR 0.962, 95% CI 0.936–0.989; P = 0.006), age (OR 1.058, 95% CI 1.002–1.119; P = 0.044), CPB time (OR 1.017, 95% CI 1.005–1.029; P = 0.005), and the number of valve replacements (OR 2.024, 95% CI 1.144–3.582; P = 0.015) were independent predictors of postoperative AKI (Additional file 1: Table 1). This evidence concerns the gene GSTM1 and acute kidney injury.