Renal morphology after cyclosporin A therapy in rheumatoid arthritis patients. International Kidney Biopsy Registry of Cyclosporin (Sandimmun) in Autoimmune Diseases.

Because cyclosporin A (CyA) has the potential of causing structural damage to renal tissue, kidney biopsies from 41 patients with RA treated with CyA at a maximum dose of 4.6 +/- 1.2mg/kg/day (mean +/- SD) for 16 +/- 7 months, were compared to kidney biopsies from 11 RA patients not treated with CyA and 41 sex- and age-matched control subjects without RA (kidney donors). Four patients in the CyA group but none in the control groups had morphological features of CyA nephropathy, defined as at least moderate focal interstitial fibrosis with tubular atrophy, arteriolar alterations or both. The dose of CyA and the initial serum creatinine level, but not treatment duration, were higher in patients with CyA nephropathy than in those without it. None of the 24 patients whose CyA dose did not exceed 5 mg/kg/day and whose serum creatinine did not rise by 50% or more above his or her pre-CyA level developed CyA nephropathy. These results indicate that the therapeutic conditions which have been shown to minimize the risk of CyA nephropathy in other autoimmune diseases can also prevent its occurrence in RA, and that CyA nephropathy can be avoided when the following rules are observed: the initial dose should be 2 or 3 mg/kg/day; the maximum dosage should not exceed 5 mg/kg/day; serum creatinine should be monitored regularly for as long as CyA is administered, and the dose should be decreased each time creatinine rises by more than 30% above the pre-CyA level.