Comparative Study Of Serum CystatinC And Serum Creatinine In Glomerular Filtration Rate Measurement In Patients With Acute Kindney Injury

Objective:To evaluate the feasibility and clinical value of serum cystatinC in assessing glomerular filtration rate in patients with acute kidney injury.Methods:Fourty-six acute kidney injury (36male/10female), aged 56.2土18 years in intensive care unit were recruited in the study and blood saples were collected daily. Serum creatinine(Scr)was measured by enzymic method.Cys C was detected by ELISA(Enzyme-Linked Immunoadsorbent Assay) and glomemlar filtration rate(GFR)was estimated by Cockrofi—Gault equation.AKI was diagnosed according to ADQI(RIFLE) criteria.The correlations among SCysC, Scr and Ccr were compared by using pearson correlation analysis. Multiple regression analysis was also used to understand the influential factors to the SCysC concentration. In order to compare the diagnostic value of SCysC and Scr, the Receiver Operating Charateristic curve(ROC) was calculated and sensitivity(Sen), specificity (Spe), accuration(Acc) of SCysC and Scr were obtained and analyzed. All data were analyzed by using statistical software of SPSS13.0.Result:46 patients developed AKI to some degree,among which 19,11and 16patients fulfilled staging 1 ,staging 2 ,and staging 3 respectively. 71 patients without AKI served as controls.In patients with AKI,Cys C was significantly increased than that in patients who did not develop AKI(P<0.01). Serum Cys C was linearly correlated with serum creatinine(r=0.877,P<0.01),also[CysC]-1 with estimated GFR (R=0.924,P<0.01). when AKI was diagnosed according to eGFR<=60 ml/min/1.732,with the staging 1 patients serum Cys C was demonstrated a highly diagnostic value to detect AKI ,The area under the curve(AUC)of the ROC for SCysC was 0.932(95%confidence interval,0.885-1.044,p<0.01) and The area under the curve(AUC)of the ROC for SCr was 0.864(95% confidence interval,0.791-1.066,p<0.01), there are significant statistical differentce between SCysC and Scr (P<0.01).With total patients there is also signifence difference. At a cutoff of 1.832mg/L, SCysC reached a 88.7% ACC, while at a cutoff of 123.5 umol/L, Scr has a 82% ACC ,there are significant statistical differentce between SCysC and Scr (P<0.05). The sensitivities were 95.7% for CysC and 82.6% for Scr with total patients, the sensitivities were 89.5% for CysC and 57.9% for Scr with staging 1 patients, there are significant statistical differentce between SCysC and Scr. The concentration of SCysC is not affected by age, gender, body weight, hemoglobin, serum protin, glucose,total bilirubin .Conclusions:Cystatin C can be one of the early detection markers of AKI.Serum cystatin C is superior to serum creatinine as a predictive marker of AKI in an early stage.