Definition
Membranoproliferative (mesangiocapillary) glomerulonephritis (MPGN) is a pattern of glomerular injury with mesangial proliferation and basement membrane remodelling, producing a hypercellular, lobular glomerulus. It typically causes a mixed nephritic-nephrotic picture.
Classification
Modern classification uses immunofluorescence:
- Immune-complex MPGN — driven by chronic antigenaemia/immune complexes: hepatitis C (with cryoglobulinaemia), hepatitis B, chronic infection, autoimmune disease
- Complement-mediated (C3 glomerulopathy) — alternative-pathway dysregulation, including dense deposit disease; a C3 nephritic factor may be present
(The older "type 1/2/3" terminology maps roughly onto these.)
Clinical presentation
- Features overlap the nephritic and nephrotic spectrum: haematuria, proteinuria (often nephrotic-range), hypertension, impaired function
- Low complement (C3) is characteristic
Investigations
- Complement (low C3), hepatitis serology, cryoglobulins, autoimmune screen
- Renal biopsy: "tram-track" double-contour GBM, mesangial interposition; immunofluorescence separates immune-complex from C3 disease
Management
- Treat the underlying cause (e.g. antiviral therapy for hepatitis C)
- Supportive RAS blockade for proteinuria and blood pressure
- Immunosuppression for idiopathic/progressive disease; emerging complement-directed therapy for C3 glomerulopathy
- Prognosis is variable and often guarded
MRCP-specific traps
- Low C3 narrows the differential — MPGN sits alongside post-strep GN and lupus.
- Hepatitis C + cryoglobulinaemia is the classic secondary cause to screen for.
- The "tram-track" GBM is the buzz-phrase biopsy finding.
Summary
MPGN is a mesangiocapillary GN causing a mixed nephritic-nephrotic picture with low complement and a "tram-track" GBM. It is either immune-complex (hepatitis C/cryoglobulins) or complement-mediated (C3 glomerulopathy). Treat the cause, block the RAS, and use immunosuppression for progressive disease.
nephrologyglomerulonephritismrcp part 2