Nephrotic Syndrome Due to Primary Nephropathies

Abstract

The nephrotic syndrome is characterized by massive proteinuria, hypoproteinemia, and usually hyperlipemia and generalized edema, with or without varying degrees of hematuria, hypertension, and azotemia. Normally, children excrete less than 60 mg of protein in an overnight 12-hour collection of urine, and less than 150 mg in a 24-hour sample. In the nephrotic child, the magnitude of proteinuria exceeds 200 mg in an overnight sample and 1.5 gm in a 24-hour collection. Recognition that the underlying renal histopathology in a nephrotic child has significant implications for response to treatment and for prognosis has led to attempts to predict the type of lesion using various criteria. The associated presence of hematuria, hypertension, or azotemia in individual nephrotic children is remarkedly inconsistent and does not correlate accurately with the underlying histopathology. However, consideration of these plus additional readily obtained data frequently will permit a more reliable prediction of the probable histopathology and potential response to therapy. Such information will include the age of the patient, ancillary physical findings, and selected laboratory studies. From that perspective, the purpose of this review is to discuss the implications of the composite clinical and laboratory findings for diagnosis and management in the child with the nephrotic syndrome. These will include indications for renal biopsy, which is the definitive test in these conditions.