Discrimination between postinfectious IgA-dominant glomerulonephritis and idiopathic IgA nephropathy

Background: A unique form of postinfectious glomerulonephritis (PIGN) with IgA-dominant deposition mimicking IgA nephropathy has been increasingly reported. Methods: We compared the clinical and histological features of 12 patients with postinfectious IgA-dominant glomerulonephritis to 134 patients with idiopathic IgA nephropathy. Results: In addition to hypocomplementemia and subepithelial hump-shaped deposits characteristic of PIGN, patients with postinfectious IgA-dominant glomerulonephritis had older age (62.3 +/- 16.9 vs. 37.9 +/- 16.3 years; p < 0.001) and more frequently presented with acute renal failure (83.3% vs. 10.4%; p < 0.001) than patients with idiopathic IgA nephropathy. Moreover, glomerular changes including endocapillary proliferation, neutrophil infiltration, and capillary loops deposits by immunofluorescence were more commonly present in postinfectious IgA-dominant glomerulonephritis group (p < 0.001). Conclusions: PIGN could be characterized by glomerular IgA-dominant deposition resembling idiopathic IgA nephropathy. It is essential to differentiate postinfectious IgA-dominant glomerulonephritis from idiopathic IgA nephropathy because of the different treatments and prognosis of the two diseases.