Value of serum cystatin C to the early diagnosis of acute kidney injury in critical patients

Objective To study the value of cystatin C to the early diagnosis of acute kidney injury in the critical patients.Methods A total of 46 critical patients with acute kidney injury(abservation group) and 71 healthy controls(control group) were measured the serum creatinine with enzymic method,were detected cystatin C with ELISA and were estimated glomemlar filtration rate with Cockrofi-Gault equation.The diagnostic value of cystatin C was calculated with ROC.All data were analyzed by using of statistical software of SPSS13.0.Results In the abservation group,there were 19,11 and 16 patients in stages 1,2 and 3 of acute kidney injury.In patients with acute kidney injury,serum cystatin C was significantly higher in the abservation group than that in control group(P0.01).Serum cystatin C was linearly correlated with serum creatinine(r=0.877,P0.01),and(cystatin C)-1 was linearly correlated with estimated glomerular filtration rate(r=0.924,P0.01).The cutoff of cystatin C was 1.832 mg/L and serum creatinine was 123.5 μmol/L.The accuracy as well as the positive and negative preditive values of cystatin C were higher than those of serum creatinine in diagnosing acute kidney injury(P0.01).The sensitivity of cystatin C(89.5%) was obviously higher than that of serum creatinine(57.9%) in stage 1 patients(P0.05).There were no significant differences in the sensitivities between stage 2 and stage 3 patients(P0.05).Conclusion Serum cystatin C can be one of the endogenous markers for glomerular filtration rate in the critical patients with acute kidney injury,and it can show acute kidney injury much earlier than serum creatinine.