Serum Cystatin C:The Sensitive Parameter in Diagnosing Early Renal Impairment

Objective:To evaluate the applicability of serum cystatin C in patients with renal impairment.Methods:Serum samples were abtained from 84 cases with renal diseases,Serum cystatin C concentration was determined by enzyme linked immunosorbent assay(ELISA),Serum creatinine(Scr) by Jaffe method and Creatinine clearance rate(Ccr) were measured,glomerular filtration rate(GFR) by 99mTc-DTPA clearance was considered to be a Gold Standard,the correlation between GFR and the above three parameters were compared, the area under the Receiver Operating Charateristic curve(AUC ROC)and the likelihood ratio(LR)were used for evaluating the reliability of cystatin C.Results:The significant correlation were found between GFR and cystatin C、Scr、Ccr,and that of between GFR and cystatin C was the most strongest. The AUC ROCfor cystatin C、 Scr、Ccr was 0.989、0.926、0.942 respectively,and there was significant statistical differentce between cystatin C and Scr(P0.05),but no statistical difference between cystatin C and Ccr(P0.05).LR of serum cystatin C was the best among the above three parameters.Conclusion:Serum cystatin C determination is an accuate and reliable parameter of GFR in patients with impaired renal function and there is guidance purpose for diagnosing early renal impairment.