IgA-Dominant Postinfectious Glomerulonephritis: Not Peculiar to Staphylococcal Infection and Diabetic Patients

Background: IgA-dominant postinfectious glomerulonephritis (PIGN) is a unique form of PIGN. It has been linked to staphylococcal infection and underlying diabetic glomerulosclerosis. However, the significance of glomerular IgA-dominant deposition in PIGN remains unclear. Methods: We reported 10 patients with IgA-dominant PIGN encountered at a single center, each characterized by subepithelial humps. Their demographic, clinical, and renal biopsy findings were summarized and compared with the data of 32 patients with non-IgA-dominant PIGN. Results: The mean age was 57 years. An immunocompromised background was present in 70% of patients; only one patient had diabetes mellitus. The causative infectious agents included Staphylococcus (30%), Streptococcus (20%), and gram-negative organisms (50%). Decreased serum complement was present in 60%. Increased serum IgA was noted in 75%. The mean peak serum creatinine was 5.1 mg/dL, and 20% required acute dialysis. Diffuse endocapillary-proliferative glomerulonephritis was found in all cases, and three patients also had crescentic glomerulonephritis. Electron microscopy revealed large subepithelial hump-shaped deposits in all cases. At the last follow-up, one patient had died, five had achieved complete recovery, three had persistent renal insufficiency, and one was on chronic dialysis. Compared to patients with non-IgA-dominant PIGN, increased serum IgA was more commonly present in IgA-dominant group (p= 0.007). There were no significant differences in other clinical parameters and outcome between the two groups. Conclusions: IgA-dominant PIGN resembles poststreptococcal glomerulonephritis in its histological spectrum and ultrastructural appearance. Increasing serum IgA may be involved in the pathogenesis of this form of PIGN. Our data suggested that IgA-dominant PIGN was not peculiar to staphylococcal infection and diabetic patients.