Renal biopsy specimens from patients with rheumatoid arthritis and apparently normal renal function after therapy...

Renal biopsies were performed in 14 patients with severe rheumatoid arthritis who had no evidence of compromised renal function after completion of treatment with low-dose cyclosporine (< or = 5 mg/kg/d). Mean serum creatinine at the time of biopsy was 0.84 mg/dL (range, 0.59 to 1.23 mg/dL). In the 13 patients who had received 6 months of cyclosporine therapy, mild glomerular expansion was noted in two biopsy specimens, obsolescent glomeruli (range, 5% to 20%) in five, and glomerular amyloid deposits in one. Five biopsy specimens had mild and three had mild to moderate interstitial fibrosis. Moderate interstitial fibrosis with a striped pattern was attributed to cyclosporine in the 14th patient. The results of a second biopsy performed in one patient after a further 18 months of therapy were unchanged. Although the renal biopsy changes were minimal in 13 patients and pathologic features characteristic of cyclosporine nephropathy were absent from all but one biopsy, a greater frequency of adverse effects due to cyclosporine could not be excluded. In the absence of clinical data, long-term cyclosporine therapy must be administered with caution to patients with rheumatoid arthritis, who commonly have underlying renal damage, and the value of renal biopsies in predicting and preventing end-stage renal failure remains to be determined.