Membranous nephropathy in patients with rheumatoid arthritis: relationship to gold therapy.

Of 90 patients with membranous nephropathy proved by biopsy, 8 (8.9%) had pre-existing rheumatoid arthirtis. Four of these eight patients received systemic treatment with gold. Two others received only token amounts of gold. In two patients who received gold, the renal lesions did not occur until months after discontinuance of gold therapy. We found that clinically significant renal lesions (lesions associated with proteinuria) in patients with rheumatoid arthritis were more likely to be membranous nephropathy than occult amyloidosis or adult lipoid nephrosis. The membranous lesion in patients with rheumatoid arthritis may be difficult to identify by light microscopy, and, although special strains can be helpful, the pathology is frequently sufficiently subtle to require immunofluorescence and electron microscopy for definitive diagnosis. We postulate that chrysotherapy may not be the cause of membranous nephropathy in patients with classic rheumatoid arthritis in whom gold has been used. Whether it merely exacerbates a lesion already present in these patients, or whether it plays little or no role in the development of membranous nephropathy is an unsettled question. Our data lead to think that RA can induce MN and that gold is not the primary inciting agent.