Serum Cystatin C As A Marker For Detection Of Early Renal Disfunction In Patients With Chronic Kidney Disease

Objective: To evaluate the applicability of serum cystatin C as a endogenous marker for detection of early renal disfunction in patients with chronic kidney disease. Methods : Serum samples were obtained from 88 cases with chronic kidney disease, collected from July in 2005 to February in 2006 among our hospitalized patient. Serum cystatin C concentration was determined by particle- enhanced turbidimetric immunoassay (PETIA), Serum creatinine(Scr) by alkaline trinitrophenal method and Creatinine clearance rate(Ccr) were measured for every patient .Meanwhile, glomerular filtration rate( GFR) measure 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 Characteristic 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^ROC for cystatin C, Scr , Ccr was 0.980, 0.914 , 0.941 respectively, and there was significant statistical difference between cystatin C andScr (P<0.05), but no statistical difference between cystatin C and Ccr (P >0.05). LR of serum cystatin C was the best among the above three parameters. Conclusion: Serum cystatin C determination is an accurate and reliable parameter of GFR .It can be a better endogenous marker for detection of early renal disfunction in patients with chronic kidney disease than serum creatinine and Ccr.