RESUMO
INTRODUCTION: IgAN occurs following abnormal IgA deposition in the glomerular mesangial regions. It is the most common primary glomerular disease and one of the causes of ESRD, so it is necessary to identify clinical and histopathological findings that predict progression to ESRD. In the physiopathology of this disease, C4d causes serious renal injuries and should be counted as a significant prognostic factor too. This study examined C4d biomarker and compare it with findings affecting prognosis, to determine the predictive value of C4d in progression to ESRD in IgAN. MATERIALS AND METHODS: In this study, all biopsy samples of IgAN patients who referred to Imam Reza Hospital in Tabriz were collected for four years. Their samples were evaluated C4d immunohistochemical staining and positive samples have compared with Clinical-histopathological findings affecting prognosis. RESULTS: In this study, C4d positivity showed a significant association with mesangial hypercellularity (p = 0.001), segmental glomerulosclerosis (p = 0.003), and endocapillary hypercellularity (p = 0.001); however, it did not show a significant relationship with tubular atrophy/interstitial fibrosis (p = 0.08). The study also found that C4d positivity was significantly (p < 0.05) correlated with hypertension, increased proteinuria, hematuria, high creatinine, and decreased mean eGFR. CONCLUSION: This study showed that immunohistochemical staining of C4d is a useful method for evaluating the prognosis of the severity of renal injuries in patients with IgAN and could be a valuable alternative for most Clinical-histopathological factors routinely used as predictive factors for its progression to ESRD, especially when the biopsy specimen size is small and insufficient for other studies.