- Membranous nephropathy usually presents with the nephrotic syndrome, often with normal or near-normal GFR.
- Membranous nephropathy may be a primary renal disease or associated with a systemic disease (e.g., malignancy, SLE, or infections such as hepatitis B, syphilis, hepatitis C, or schistosomiasis) or drug ingestions (e.g., penicillamine, gold).
- Approximately one-third of patients with membranous nephropathy progress to ESRD; the remainder enter remission or have stable or very slowly declining renal function.
- Pathologic findings include thickening of the GBM, often with GBM -spikes- on light microscopy with subepithelial deposits of IgG and C3 on immunofluorescence and electron microscopy.
- Because of the generally good outcome, treatment usually is reserved for patients with poor prognostic factors (age >50, male gender, hypertension, reduced GFR, proteinuria >10 g/d, or marked interstitial fibrosis on renal biopsy) or severe symptomatic nephrotic syndrome.
- Treatment options include high-dose alternate-day glucocorticoids in conjunction with a cytotoxic agent (e.g., chlorambucil, 0.2 mg/kg/d, or cyclophosphamide, 1.5-2.5 mg/kg/d) for 6-12 months and, in nonresponders, cyclosporine, 3.5 mg/kg/d, for 12 months. Alternative agents include mycophenolate mofetil, rituximab, and possibly pentoxifylline.