[Value of serum IgA/C3 ratio in the diagnosis of IgA nephropathy and its correlation with the clinicopathological features].

OBJECTIVE: To investigate the value of serum IgA/C3 ratio in the diagnosis of IgA nephropathy and explore its relationship with the clinicopathological features of the patients. METHODS: Sixty-six patients with IgA nephropathy, 111 with other glomerular diseases, and 40 healthy control subjects without kidney disease were tested for serum IgA and C3 levels using CRM470 adjusted standardized immune turbidimetric method, and the IgA/C3 ratio was calculated. According to Oxford and Lee's classification criteria, we analyzed the pathological grades of the renal biopsy samples from patients with IgA nephropathy. The ROC curve was used to assess the value of serum IgA and IgA/C3 ratio in predicting IgA nephropathy. RESULTS: Patients with IgA nephropathy had an elevated serum IgA/C3 ratio than those with other glomerular diseases and the control subjects, with an area under the ROC curve of 0.776. An elevated serum IgA/C3 ratio was not found to significantly correlate with the pathological grade of renal biopsy samples in patients with IgA nephropathy. CONCLUSION: In the absence of renal biopsy findings, serum IgA/C3 ratio can help in the diagnosis of IgA nephropathy.