Cyclosporine in the treatment of idiopathic nephrosis.

Within the past decade, there have been numerous reports on the use of cyclosporine in idiopathic nephrosis. In this review, the results of both uncontrolled and controlled studies of the therapeutic effects of cyclosporine in steroid-sensitive/dependent idiopathic nephrosis and in steroid-resistant idiopathic nephrosis are analyzed. Cyclosporine is efficient in up to 80% of patients with steroid-sensitive/dependent idiopathic nephrosis. Most patients, however, relapse when the drug is withdrawn, thus necessitating prolonged treatments. Although cyclosporine is less efficient in patients with steroid-resistant idiopathic nephrosis, a few studies seem to indicate that this drug may be successful in some patients, especially if combined with corticosteroids. There is no evidence that cyclosporine can prevent the recurrence of nephrotic syndrome on the graft after renal transplantation. However, in patients in whom disease has recurred, high doses of cyclosporine may be effective alone or in combination with plasma exchanges. The main worrisome side effect of cyclosporine is chronic nephrotoxicity, which should be differentiated from acute or "functional" toxicity. Follow-up studies including pretreatment and posttreatment renal biopsies show a lack of correlation between structural damage and renal function, suggesting that a histologic examination of the renal parenchyma is the only reliable way of evaluating chronic cyclosporine nephrotoxicity.