Diagnosis of C3 Glomerulopathy
A diagnosis of C3 Glomerulopathy (C3G) requires a renal biopsy and careful review of light microscopy, immunofluorescence and electron microscopy. Broadly, C3G is defined as the predominant staining of C3 on immunofluorescence (IF) when compared to immunoglobulin (intensity >2 orders of magnitude). C3G is classified by electron microscopy findings into dense deposit disease or C3 Glomerulonephritis, depending on the presence or absence of dense osmiophilic intramembranous deposits.
Light microscopy identifies diverse patterns of glomerular injury that include MPGN, and detect additional features such as crescentic disease or markers of chronic disease such as interstitial fibrosis and tubular atrophy.