The place of cyclosporin in the management of primary nephrotic syndrome

The 3 main causes of primary nephrotic syndrome are minima change nephropathy, focal segmental glomerulosclerosis and membranous nephropathy. Corticosteroids result in remission of proteinuria in most patients with minimal change nephropathy. Many patients, however, develop corticosteroid dependency. A course of cytotoxic drugs can also achieve remission but these agents cannot be administered for prolonged periods or in repeated cycles because their toxicity is cumulative. Review of the available literature indicates that cyclosporin may maintain remission of nephrotic syndrome in about 80% of patients with corticosteroid-sensitive disease, indicating an important role for this drug in patients with frequent relapses or corticosteroid dependency. Although cyclosporin is less effective in patients with focal segmental glomerulosclerosis, which is often corticosteroid-resistant, a number of studies indicate that it may be successful both in the few steroid-sensitive patients with frequent relapses and in some corticosteroid-resistant patients. In patients with membranous nephropathy, a 6-month course of corticosteroids and cytotoxic agents may favour remission of nephrotic syndrome and protect renal function. Several studies have shown that cyclosporin can improve proteinuria, and there is a tentative suggestion that it might also protect against renal function deterioration. The risk of nephrotoxicity can be minimised if cyclosporin is used at the correct doses and if renal function is carefully monitored during treatment. In summary, cyclosporin can be considered a useful tool for treating patients with nephrotic syndrome associated with primary glomerulonephritis.