Secondary membranous nephropathy--one center experience.

Introduction: Secondary membranous nephropathy (MN) is most commonly seen in the setting of autoimmune disease, infection, and neoplasia, and with certain therapeutic agents. The aim of our study was to analyze the presenting features and outcome of the patients with secondary MN.

Patients And Methods: We retrospectively studied patients with secondary MN diagnosed between the years 1991-2002. In this period, we performed a total of 1874 renal biopsies. MN was diagnosed in 129 cases.

Results: In 40 patients (31%), an underlying primary cause was verified (70% women, 30% men, median age 49.5 years). In 18 patients (45%), the disease was drug induced, 11 patients (27.5%) had autoimmune disease, seven patients (17.5%) solid tumors, three patients (7.5%) hepatitis B, and one patient was diagnosed with both hepatitis B and prostate carcinoma. At presentation, median proteinuria was 4.09 g/24 h; 60% were nephrotic. Most of the patients had normal renal function with a median serum creatinine 79 micromol/L and a median GFR 1.285 ml/s. The patients were treated according to the underlying disease. At the end of the follow-up, the patients with drug-induced MN were in complete remission after the discontinuation of the drug. The patients with autoimmune disease were treated with immunosuppression, most of them with very good results. The outcome of the patients with neoplasia was much worse.

Conclusion: A thorough and repeated exclusion of secondary forms of MN has significant prognostic and therapeutic implications, especially in drug-induced and autoimmune MN.