Renal structure and function effects after low dose cyclosporine in psoriasis patients: a preliminary report.

Our studies on the treatment of psoriasis with cyclosporine A (CSA) have demonstrated efficacy at doses < 5 mg/kg/day. However, the nephrotoxicity of CSA at these low doses is not known and is the focus of this current study. Twenty-nine patients prospectively had pretherapy assessment of renal function including serum creatinine and glomerular filtration rate (GFR). GFR was also measured while receiving CSA as well as posttherapy. These functional studies were compared with renal biopsies taken one month after discontinuing the drug. Pretherapy GFR values were normal in all of our subjects. However, by midstudy GFR values had dropped significantly in many patients. This trend continued so that at the end of the study mean GFR values had decreased by 12% with slightly over one quarter of the patients having reductions in GFR of at least 25%. Renal biopsy findings correlated well with the functional studies in particular the GFR, with those patients having the greatest reduction in GFR showing the most renal scarring. Thus, CSA at doses < 5 mg/kg/day induces variable chronic renal injury which correlates most closely with changes in the GFR.