Gold nephropathy: tissue analysis by X-ray fluorescent spectroscopy.

Three patients developed proteinuria following gold therapy for rheumatoid arthritis. The clinical syndrome was a self-limiting proteinuria with normal renal function. By light and electron microscopic appearances the renal lesion was an epimembranous deposit form of membranous glomerulopathy. Immunofluorescent study showed granular deposits of IgG and C3 complement along glomerular basement membranes. By X-ray fluorescent spectroscopic examination, gold was seen to be present within the proximal convoluted tubular cells but was not identified in the glomerular subepithelial deposits. These findings are consistent with an immune-complex form of glomerulopathy in which gold is neither the antigen nor a hapten in the glomerular deposits, and they suggest the hypothesis that antibodies to tubular epithelial antigens induced by gold therapy may be a causative factor in the renal disease associated with gold therapy in rheumatoid arthritis.