Abstract: 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.