Cyclosporine-induced renal dysfunction.

The most practical way to assess and to quantitate the renal function in renal transplant patients is the Cockcroft-Gault equation or an equation used to estimate the glomerular filtration rate (GFR), derived from the Modification of Diet in Renal Disease study. Chronic cyclosporine (CsA) nephrotoxicity causes structural lesions in the kidney and an impairment in the GFR. Determining the composition of the interstitial collagens may be helpful to establish the diagnosis. CsA trough levels are a poor indicator of drug exposure; drug exposure should be quantitated using more accurate methods. Although routine biopsies often show histopathological evidence of structural damage, the excellent kidney graft half-life and the documentation that the creatinine clearance usually remains stable over years in CsA-treated renal transplant patients suggest that its use in kidney transplant patients does not inexorably lead to graft failure. Protocol biopsies show a high incidence of chronic structural CsA toxicity but transplant nephrectomies show that CsA nephrotoxicity as the sole cause of graft loss is extremely rare.