Reference values of serum Cystatin C and creatinine in healthy volunteers, and comparison of their evaluation of glomerular filtration function in chronic renal patients

Objective To establish the reference values of serum Cystatin C and creatinine (Scr) in healthy Chinese volunteer.Comparison of correlation and ROC curve between Cystatin C、Scr and plasma 99m Tc-DTPA clearance as standard method were studied to investigate the value of serum Cystatin C、Scr in the evaluation of glomerular filtration function(GFR) in chronic kidney disease(CKD) patients.MethodsThe concentration of serum Cystatin C was determined by particle-enhanced immunonephrology method. Scr was determined by alkaline kinetic method.The study was performed on 1 201 cases of healthy person and 265 cases of CKD patients, and GFR was estimated by the plasma clearance of 99m Tc-DTPA. The sensitivity and specificity for the diagnosis of renal impairment were calculated by the receiver operating characteristic curves (ROC).Results There was no statistically different between age groups for Cystatin C and Scr.The 99% double-sided was chosen to define reference range of healthy people for Cystatin C were 0.60-1.02 mg/L for men and 0.47-0.97 mg/L for women; Scr were 63-110 μmol/L for men and 53-93 μmol/L for women.Correlation coefficients with 99m Tc-DTPA were-0.660 for serum Cystatin C,-0.534 for serum creatinine (P all0.001). Areas under the ROC curve (AUC) were 0.907 for Cystatin C, 0.862 for creatinine.The area under the ROC was statistically different between serum Cystatin C and creatinine (P0.05).Conclusion Cystatin C can truly reflect the glomerular filtration function and is a more sensitive and specific maker for GFR.