Objective To investigate the effects of ulinastatin preconditioning combined with postconditioning on kidney injury of pediatric patients undergoing living donor liver transplantation (LDLT) and the underlying mechanism.Methods Forty pediatric patients with biliary atresia,scheduled for LDLT,were randomly divided into two groups (n =20 each):the ulinastatin group and the control group using a random number table.Ulinastatin (20 000 U/kg) was diluted into 10 000 U/mL with normal saline,and it was then injected intravenously in 2 parts (1/2 was given before skin incision;1/2 at 5 min before portal vein declamping) in the ulinastatin group.In the control group,the equal volume of normal saline was given instead of ulinastatin.Blood samples and urine specimens were taken from the central vein immediately before skin incision (T0,baseline),at 30 min of anhepatic period (T1),at 1 h of neohepatic period (T2),at the end of surgery (T3),and 24 h after surgery (T4) for the determination.The concentrations of serum and urine β2-microglobulin (β2-MG) were measured using an immunonephelometric method.The levels of serum TNF-α,IL-6 and IL-18 were measured using an ELISA method.The serum concentrations of creatinine (Cr) and blood urea nitrogen (BUN) were measured using a colorimetry method.Results The serum Cr,BUN,β2-MG and urine β2-MG concentrations were higher at T2-4 than at T0 in the two groups (P＜0.05 or 0.01).As compared with the control group,the serum Cr,BUN,β2-MG and urine β2-MG concentrations were significantly decreased in the ulinastatin group (P＜0.05 or 0.01).The serum levels of TNF-α,IL-6 and IL-18 were higher at T2 4 than at T0 in the two groups (P＜0.05 or 0.01).As compared with the control group,the serum levels of TNF-α,IL-6,and IL-18 were significantly decreased in the ulinastatin group (P＜0.05 or 0.01).Conclusion Ulinastatin preconditioning combined with postconditioning can alleviate kidney injury in pediatric patients undergoing LDLT to some extent,which may be related to inhibiting the excessive release of inflammatory factors.