[Renal side effects of treatment with cyclosporin A in rheumatoid arthritis and after bone marrow transplantation].

Renal function was studied prospectively in 6 patients with rheumatoid arthritis and non-prospectively in 5 patients after bone marrow transplantation. Both groups were treated with cyclosporin A. Functionally and histologically the results suggest tubulotoxicity of cyclosporin A which seems to be dose-related and reversible. Also found in the urine of these patients were yellow, as yet undescribed crystalline bodies often included in casts.