Epidemiology and natural course of idiopathic nephrotic syndrome.

The term "idiopathic nephrotic syndrome" is poorly defined and is used to refer to a variety of glomerular lesions. This article seeks to clarify the situation by considering the case for treating minimal-change nephropathy, focal and segmental glomerulosclerotic lesions, and mesangioproliferative lesions with predominantly IgM deposition as separate disease entities. In children, nephrotic syndrome has a pattern different from that in adults, in whom a wider pathogenetic spectrum is seen. There is support for the use of prospective clinicopathological data as the basis of identifying those patients with nephrotic syndrome who will progress to end-stage renal failure. Very heavy, persisting proteinuria is one marker of such progression and is also an indicator of metabolic complications, such as cardiovascular disease, which further increase the risks of mortality and morbidity in this group of patients.