Abstract: Objective To analyze the level and correlation of Cystatin C(CysC), interleukin-2(IL-2) and C3 in patients with chronic glomerular nephropathy and to provide reference for the clinical diagnosis of this disease. 
Methods A total of 138 patients with chronic glomerular nephropathy were selected as the research group, and 80 healthy physical examinees in our hospital as the control group. Serum CysC, IL-2 and C3 levels were detected, and their expression differences in the two groups and in patients with different severities of disease were analyzed. The correlation among the three was analyzed. 
Results Compared with the control group, CysC levels were higher, while IL-2 and C3 levels were lower in the research group(P＜0.05). The ROC curve showed that combined detection of CysC, IL-2 and C3 had a higher diagnostic value for chronic glomerular nephropathy than CysC, IL-2 and C3 alone(P＜0.05). Univariate analysis showed that the incidence of chronic glomerular nephropathy was not related to the patient's gender, age, serum uric acid, and comorbidities, with no significant difference(P＞0.05), but was related to smoking history, drinking history, obesity, CysC, IL-2 and C3 levels(P＜0.05). Correlation analysis showed that CysC was positively correlated with renal function damage(eGFR)(r=0.404, P＜0.001); IL-2 was negatively correlated with eGFR(r=-0.375, P＜0.001); C3 was negatively correlated with eGFR(r=-0.504, P＜0.001). Chronic glomerular nephropathy served as dependent variables, and significant variables of univariate analysis as independent variables were incorporated into the biclassification multi factor Logistic regression model, which showed that CysC, IL-2, and C3 were influencing factors of the occurrence of chronic glomerular nephropathy(P＜0.05). CysC was negatively correlated with IL-2(r=-0.250, P=0.003); CysC was negatively correlated with C3(r=-0.373, P=0.001); IL-2 was positively correlated with C3(r=0.232, P=0.006). 
Conclusion Serum CysC levels are increased, while IL-2 and C3 levels are decreased in patients with chronic glomerular nephropathy, which is related to eGFR of the patients. The disease can be diagnosed and evaluated early based on their level.

Key words: nephropathy, Cystatin C, interleukin-2, renal function impairment