Treatment of the idiopathic nephrotic syndrome
Authors: B M Tune, S A Mendoza
Journal: Journal of the American Society of Nephrology (1997)

This review compares the biopsy patterns, complications, responses to therapy, and long-term outcomes of idiopathic NS in children and adults. On first examination, distinctions between the pediatric and adult diseases seem more quantitative than absolute. However, underlying determinants of outcome, including immunocompetence, growth, maturity, and senescence, can present very different challenges for pediatricians and internists. The major biopsy patterns in pediatric NS include MCD, FSGS, and DMP. MCD is overwhelmingly the most frequent and most steroid-responsive of the three but commonly presents problems of massive edema, serious bacterial infections, and multiple relapses. Because of the prompt response of pediatric MCD to corticosteroids, steroid resistance in children has generally been defined as persistence of proteinuria after 1 month of daily followed by 1 month of intermittent prednisone administration. By this criterion, nephrotic FSGS is usually steroid-resistant and, if not controlled by more aggressive therapy, typically progresses to ESRD. DMP is commonly steroid-resistant but may slowly resolve. It is not clear to what extent remissions of DMP represent a delayed response to steroids or would have occurred without treatment. Biopsies showing a few globally obsolescent glomeruli or mild mesangial hypercellularity may be associated with greater difficulty in management but have been included in the broad category of MCD. Moreover, evolution of patterns in serial biopsies, variable steroid-responsiveness of FSGS and DMP, and progression of some cases of MCD to ESRD suggest common features in the three major categories. Among adults with idiopathic NS, FSGS is the most frequent biopsy pattern, followed by MN (which is rare in children) and then by MCD. In contrast to its pediatric counterpart, MCD in adults is less regularly and more slowly responsive to corticosteroids and in the elderly is more commonly associated with hypertension and renal failure. MCD in adults is less likely to relapse once remission is achieved. Adults with FSGS present less commonly with severe edema than do children with this lesion. Although children and adults with FSGS present similar challenges of resistance to therapy and loss of renal function, the more aggressive oral steroid regimens used by internists preclude strict comparisons between pediatric and adult series. There is insufficient information to support a systematic analysis of DMP in adults. Cytotoxic agents and cyclosporine have been used with varying success in children and adults with difficult cases of NS. In MCD, an alkylating agent can increase the likelihood and duration of remission. Cyclosporine can also improve control in MCD, but continued treatment is often needed to maintain remission. Significant control of steroid-resistant FSGS has not been achieved with limited courses of an alkylating agent or cyclosporine. Longer courses of either of these immunosuppressants, especially when combined with intermittent steroid administration, can produce more complete and/or more sustained remissions. However, cyclosporine nephrotoxicity is more severe in FSGS than in MCD and in steroid-resistant than in steroid-dependent NS, regardless of biopsy pattern. A protocol combining iv M-P pulses, alternate-day prednisone, and an alkylating agent in steroid-resistant pediatric FSGS has produced the highest percentage of sustained remissions with normal renal function, of all reported regimens. Controlled trials of this and other combined drug protocols are needed in children and adults.