Background Membranous nephropathy (MN) is famous as extra articular lesion of rheumatoid arthritis (RA). Most of them are caused by Disease-modifying antirheumatic drugs (DMARDs), especially bucillamine. But MN that is not caused by drug (non drug-induced MN) can occur in patients with RA. The characteristics of non drug-induced MN and the differences with bucillamine-induced MN are unclear.
Objectives To investigate differences between bucillamine-induced MN and non drug-induced MN in patients with RA.
Methods 39 patients with RA who had a diagnosis of membranous nephropathy in our hospital from January 1985 to December 2009 were enrolled in this study. Membranous nephropathy was revealed by renal biopsy in all cases. They are categorized as having bucillamine-induced MN or non drug-induced MN. All patients checked creatinine and proteinuria both at baseline and at follow-up. These data and pathological findings were compared in two groups.
Results Bucillamine-induced MN was 26 subjects and non drug-induced MN was 9 subjects. In Bucillamine-induced MN group and non drug-induced MN group, follow up time (6.1±4.7 vs. 6.4±4.9 years, p=0.84), creatinine at baseline (0.8±0.3 vs. 1.1±0.5 mg/dl, p=0.23), proteinuria at baseline (3.6±3.2 vs. 3.6±4.1 g/day, p=0.58) and creatinine at follow-up (0.8±0.3 vs. 1.4±0.9 mg/dl, p=0.12) did not have the difference. Proteinuria at follow-up was lower in Bucillamine-induced MN group compared to non drug-induced MN group (0.1±0.1 vs. 1.3±2.8g/day, p<0.05). In bucillamine group, proteinuria disappeared in all of cases after discontinuance of medicine. In non drug-induced MN group, the course was various. In some cases of this group, proteinuria disappeared after decrease of RA activities by treatment of RA. The findings of the light microscope in two groups were not different. But in an electron microscope, the bucillamine group had little quantity of the deposit and the size was uneven.
Conclusions In bucillamine group, proteinuria disappeared after discontinuance of medicine. In some cases of non drug-induced MN, proteinuria disappeared after decrease of RA activities by RA treatment, and it was possible that the control of RA activity contribute the improvement of MN in patients with RA.
Disclosure of Interest None Declared