Membranoproliferative glomerulonephritis (MPGN) is a pattern of glomerular injury characterized by mesangial cell proliferation, capillary wall thickening from subendothelial immune deposits, and duplication of the glomerular basement membrane (creating a 'tram-track' appearance on light microscopy). Immune complex-mediated MPGN results from chronic infection (hepatitis B or C, bacterial endocarditis), autoimmune disease (SLE), or monoclonal gammopathies, where circulating immune complexes deposit in the subendothelial space, activating complement and recruiting inflammatory cells. Complement-mediated MPGN (C3 glomerulopathy) involves dysregulation of the alternative complement pathway (from C3 nephritic factor autoantibody or genetic mutations in complement regulatory proteins), causing uncontrolled C3 activation and deposition in the glomerulus. Clinical presentation includes nephritic features (hematuria, hypertension, low complement levels) with nephrotic features (proteinuria, edema). The nurse monitors renal function and urinalysis, monitors complement levels (C3, C4), assesses blood pressure (hypertension accelerates progression), monitors for progression of renal dysfunction, administers prescribed therapy targeting the underlying cause (antivirals for hepatitis, immunosuppression for autoimmune forms, complement inhibitors such as eculizumab for C3 glomerulopathy), and manages nephrotic complications.