C3 and glomerulonephritis: However, a previous study used the presence of at least three of the following criteria for diagnosis [16]: (1) clinical or laboratory evidence of infection preceding or concurrent with onset, (2) reduced serum complement, (3) endocapillary proliferative and exudative glomerulonephritis, (4) C3-dominant or co-dominant glomerular immunofluorescence staining, and (5) hump-shaped subepithelial deposits.