ABSTRACT
Nephrotic syndrome (NS) is one of the most common glomerular disorders of childhood. It is characterized by proteinuria that is severe enough to cause hypoalbuminemia and edema. e rst description of a nephrotic child was published in 1484, when Cornelius Roelans of Belgium described “swelling of the whole body of the child” as one of 52 common diseases of children.1 Almost 250 years later, the kidney tubules were implicated in the pathogenesis of NS by eodore Zwinger, who also described deterioration of renal function in some patients.1,2 Richard Bright described NS in more detail in his classic text from 1827: however, the term “nephrotic syndrome” was not coined until 1929, in the writings of Henry Christian from Boston.3,4 Outcomes for children with NS were uniformly poor before the introduction of antibiotics in the 1930s, with mortality rates of approximately 67%.5 With widespread use of sulfonamides and penicillin to treat NS-associated infections, mortality dropped to 35% by 1950.5 e watershed moment in the history of NS was the introduction of steroids for the treatment of this disorder in the 1950s, which led to clinical remission in a majority of treated patients and a drop in mortality to 9% by 1960.5
NS is a clinical description of a constellation of ndings that can be caused by a large number of underlying primary and secondary disorders. e International Study of Kidney
Disease in Children (ISKDC) dened NS as massive proteinuria (greater than 40 mg/m2/h, or 1000 mg/m2/24 h) leading to hypoalbuminemia (less than 2.5 g/dL), edema, and hyperlipidemia.6 e urine protein-to-creatinine ratio greater than 2 also correlates well with nephrotic range or massive proteinuria. ere are many ways to categorize patients with NS, including by age at presentation, by kidney pathologic features, and by clinical response to corticosteroid therapy. Presentation of NS at less than 3 months of age is termed congenital NS and is oen caused by congenital infections or mutations in various podocyte proteins such as nephrin.7,8 Infantile NS is dened as clinical presentation between 3 months and 1 year of age and oen has a genetic basis as well (see Chapter 18). Childhood NS accounts for the majority of patients with NS and is dened as presentation between 1 and 18 years of age.
