A positive correlation was found between tubulointerstitial fibrosis (evaluated on Masson’s trichrome-stained sections) and rPRO-C3 (R2 = 0.4459, P = 0.0003), uC3M (R2 = 0.1922, P = 0.0364), and TUM (R2 = 0.2285, P = 0.0182), which strengthens the relevance of these parameters as novel urinary biomarkers of renal fibrosis (Fig. 2, H–J). Here, C3 is linked to renal fibrosis.