Evaluation of Serum Cystatin C as Marker for Glomerular Filtration Rate in Children.

Objective To investigate whether evaluation of serum cystatin C level can be a reliable,sensitive and safe method to determinate glomerular filtration rate(GFR) in children.Methods 55 pediatric patients(31 males and 24 females,aged 2 to 16) with different renal functions were all examined by three kinds of methods,which were clearance of serum creatinine(Ccr)(4 h urine method) level,serum Cystatin C level,and serum creatinine level(Scr) respectively. In addition,the patients were divided into three groups: 25 cases with normal renal function,Ccr(ml/ min/1.73 m~2)80;23 cases with minor and moderate lesion,30Ccr80;7 cases with severe lesions,Ccr30.50(26 males and 24 females)healthy children aged 2 to 16 were control.Results 95% reference intervals of serum cystatin C ranges 1.05±0.28 mg/L on healthy children(2 ys).There was a significant difference of Scys C between experiment groups and control,a positively linear correlation was found between Scys C and Scr(P0.05).Correlations between 1/Scys C and Ccr were better than that between 1/Scr and Ccr.Logistic regression analysis showed a correlation of serum cystatin C level with GFR,while nothing with age,height and weight.Diagnostic accuracy in the identification of GFR reduction was measured by area under the receiver-operating characteristic plot,suggesting serum cystatin C was more accurate than creatinine and height/creatinine.A cutpoint cystatin C concentration of 1.30 mg/L develop 95% sensitivity,90% speciality and 93% accuracy for detecting GFR reduction.Conclusion Unlike creatinine,serum cystain C reflects renal function in children independent of many extrinsic factors such as age,height,sex and weight.Thus serum cystatin C level,which demonstrate the renal filtration dysfunction more sensitively than Scr and height/creatinine,may be used as an ideal endogenou marker of glomerular filtration rate in children.