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Membranoproliferative glomerular nephritis

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membranoproliferative glomerulonephritis histology tram track double contour

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"membranoproliferative glomerulonephritis" AND treatment

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Membranoproliferative Glomerulonephritis (MPGN)

MPGN is not a single disease but a histologic pattern of glomerular injury seen on kidney biopsy - characterized by mesangial cell proliferation, increased mesangial matrix, and thickening/duplication ("splitting") of the glomerular basement membrane (GBM). It accounts for roughly 5-10% of cases of nephrotic syndrome in children and adults - Robbins Basic Pathology, p. 507.
Membranoproliferative glomerulonephritis histology showing mesangial proliferation, granular IgG/C3 deposits on immunofluorescence, and subendothelial electron-dense deposits
(A) Light microscopy - mesangial proliferation, GBM splitting, lobular accentuation (silver stain). (B) Immunofluorescence - granular IgG deposits. (C) Electron microscopy - subendothelial electron-dense deposits.

Modern classification (based on immunofluorescence, not just EM pattern I/II/III)

1. Immune complex-mediated MPGN (IC-MPGN) - the majority (~80%) of cases. Immune complexes deposit in the mesangium and subendothelial space, activating both classical and alternative complement pathways. Causes include:
  • Infections: hepatitis C (often with cryoglobulinemia), hepatitis B, bacterial endocarditis, infected shunts, malaria, schistosomiasis, leprosy
  • Autoimmune disease: SLE, Sjögren syndrome, rheumatoid arthritis, mixed connective tissue disease
  • Monoclonal gammopathy (plasma cell or B-cell clonal Ig deposition)
  • Idiopathic (a minority, more common in adolescents/young adults)
2. Complement-mediated MPGN (C3 glomerulopathy) - driven by dysregulation of the alternative complement pathway rather than immune complexes. Includes:
  • Dense deposit disease (formerly "MPGN type II") - characteristic ribbon-like intramembranous C3 deposits on EM; can be associated with partial lipodystrophy
  • C3 glomerulonephritis - C3 deposits without the dense intramembranous ribbon
  • Driven by C3 nephritic factor (autoantibody stabilizing the alternative pathway C3 convertase), or mutations/deficiencies of factor H, factor I, or other complement regulators
3. MPGN-pattern without immune complexes or complement - seen in chronic thrombotic microangiopathies (TTP, antiphospholipid syndrome, radiation nephritis, drug-induced TMA, POEMS syndrome, sickle cell disease) - driven by chronic endothelial injury rather than immune deposition.
(Sources: Goldman-Cecil Medicine, p. 1260; Robbins & Kumar Basic Pathology, p. 507; Comprehensive Clinical Nephrology, 7th ed.)

Clinical features

  • Presents with proteinuria (often nephrotic-range), hematuria, and sometimes nephrotic syndrome; slowly progressive course if untreated
  • Low serum C3 and C4 intermittently in IC-MPGN; isolated low C3 (with normal C4) is typical in dense deposit disease/C3 glomerulopathy, reflecting alternative pathway activation
  • Diagnosis requires kidney biopsy; light microscopy shows lobular accentuation and GBM "tram-track" duplication (from mesangial cell/matrix interposition), immunofluorescence localizes IgG/complement vs. C3-dominant deposits, and EM localizes deposits (subendothelial/mesangial in IC-MPGN vs. intramembranous ribbon-like in dense deposit disease)
  • Every biopsy-proven case should be worked up for an underlying secondary cause (infection, autoimmune disease, monoclonal gammopathy) before being labeled idiopathic; if no cause found, evaluate for a complement-regulatory disorder

Treatment

  • Treat the underlying cause first when identified (e.g., direct-acting antivirals for HCV-associated IC-MPGN, which effectively reduces recurrence risk; treatment of the autoimmune disease or monoclonal gammopathy)
  • Idiopathic IC-MPGN with proteinuria ≤3 g/day and normal renal function: supportive care alone - blood pressure control with an ACE inhibitor or ARB
  • Abnormal kidney function without crescents/active sediment: corticosteroids + immunosuppression - prednisone 1 mg/kg/day (max 60-80 mg/day) for 12-16 weeks; mycophenolate mofetil (2-3 g/day) added if suboptimal response; cyclophosphamide reserved for refractory cases
  • C3 glomerulopathy: complement-targeted therapy (e.g., eculizumab in select cases) is being used increasingly, guided by the specific complement abnormality
  • No treatment has been proven definitively effective for recurrent MPGN after kidney transplantation; recurrence risk is significant (20-45% for IC-MPGN), and HCV-endemic regions show higher graft loss from recurrence (Comprehensive Clinical Nephrology, 7th ed., p. 1474-1475)

Recent evidence note

A 2026 systematic review (Caravaca-Fontán et al., PMID 40971335) examined clinical presentation, treatment patterns, and the association of proteinuria with outcomes across C3 glomerulopathy and primary IC-MPGN - broadly consistent with the textbook framework above but underscores that proteinuria level is a key prognostic/treatment-response marker, and treatment protocols remain heterogeneous across the two disease categories. If precise, current treatment-response data are needed for a specific clinical decision, this paper is worth reviewing in full.

What's the prognosis and long-term kidney outcomes with treatment?

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