Study of serum cystatin C at assessment the glomerular filtration rate in patients with lupus nephropathy

Objective To compare the serum cystatin C(CysC) level in different stage of glomerular filtration rate in patients with systemic lupus erythematosus, and to investigate the correlation between CysC and glomerular filtration rate. Methods 128 patients with systemic lupus erythematosus in the First Affiliated Hospital of Liuzhou Medical College from January 2008 to January 2013 were selected and divided into 3 groups according to creatinine clearance rate(Ccr) values: 41 cases with Ccr≥90 mL/(min·1.73 m2) were chosen as CKD1 group, 43 cases with 60≤Ccr 90 mL/(min·1.73 m2) were selected as CKD2 group, 44 cases with Ccr60 mL/(min·1.73 m2) were chosen as CKD3 group. 30 healthy people were selected as control group. The CysC level, serum creatinine(Scr) and creatinine clearance rate(Ccr), CG-GFR were measured in each group. ROC curve was used to compare the diagnostic value. Results ①The CysC levels in CKD2 group, CKD3 group were higher than those in CKD1 group and control group; CysC levels in CKD3 group was high than that in CKD2 group, the differences were statistically significant(P 0.01), CysC levels were gradually increased along with the decrease of Ccr. ②ROC curves of CysC, CG-GFR, Scr were made by the cut point of Ccr 90 mL/(min·1.73 m2) and 60 mL/(min·1.73 m2), the differences of area under curve were statistically significant(P 0.01); ROC curves of CysC, CG-GFR, Scr were made by the cut point of Ccr 30 mL/(min·1.73 m2), the differences of area under curve was not statistically significant(P 0.05). Conclusion The diagnostic efficiency of CysC to Ccr is the highest at the Ccr 90 mL/(min·1.73 m2) and 60 mL/(min·1.73 m2). The rise of CysC levels has relation with lupus nephropathy, it can evaluate the early renal damage with medium-term lupus nephropathy sensitively.