OBJECTIVETo investigate the new biomarkers of acute kidney injury, as well as to confirm the values of response gene to complement 32 (RGC-32) for early diagnosis of acute kidney injury by comparing the values of serum creatinine (Scr) and cystatin C (CysC) in children who had undergone cardiopulmonary bypass (CPB).

METHODSixty-seven patients who had accepted CPB were recruited from the cardiac surgery intensive care unit, Children's Hospital Affiliated to Shanghai Jiao Tong University from March to June 2013 and assigned to acute kidney injury group (group AKI) or non-acute kidney injury group (group non-AKI), on the basis of the definition by the pediatric RIFLE (pRIFLE) criteria. Also 30 healthy control children were recruited. Serum samples were taken regularly from each patient after CPB at 30 min, 2 h, 4 h, 24 h, 48 h and 72 h for RGC-32. Serum samples were tested by enzyme linked immunosorbent assay (ELISA) which was employed to determine the levels of serum RGC-32. Scr and CysC were analyzed by HITACHI 7180 automatic biochemical analyzer. All the data were analyzed by receiver operator characteristic curve (ROC) and area under curve (AUC).

RESULTThe incidence of AKI was 34% (23/67), including 15 cases with risk stage AKI, 4 cases with injury stage AKI, 3 cases with failure stage AKI, 1 cases with loss stage AKI. Three out of four subjects with Failure stage AKI and the one case with Loss stage all accepted renal replacement therapy. CPB group had a higher level of serum RGC-32 than that of pre-operation after CPB 30 minute [(2.88 ± 0.68) µg/L vs. (1.39 ± 0.31) µg/L, P < 0.05]. At the same time, comparing with the non-AKI group, the levels of serum RGC-32 were higher than that of controls 30 min, 2 h, 4 h, 24 h and 48 h after CPB (t = 2.560, 2.180, 2.818, 2.226, 3.017; P < 0.05). The values for the AUC were determined for RGC-32 as 0.770, 0.707, 0.768, 0.728,0.723 and 0.770 after CPB 30 min, 2 h, 4 h, 24 h, 48 h and 72 h. The values for sensitivity of serum RGC-32 30 min, 2 h and 4 h after CPB was 0.914, 0.824, 0.824 and the values for specificity of serum RGC-32 was 0.619, 0.667, 0.810, respectively. But the values for sensitivity of CysC was 0.625, 0.813, 0.813, and specificity 0.571, 0.619, 0.571, respectively. The values for sensitivity of Scr was 0.625, 0.625, 0.813 and specificity was 0.571, 0.571, 0.524, respectively.

CONCLUSIONThe sensitivity of serum RGC-32 for detecting AKI was much higher than that of Scr and serum CysC in children who had accepted CPB, and that RGC-32 may be a new biomarker for early detection of AKI. However, the conclusion needs to be further elucidated.