The nephrotic syndrome

Abstract

The nephrotic syndrome is characterized by intermittent edema associated with considerable proteinuria, with low concentrations of certain plasma proteins, especially albumin and gamma globulin, and with hyperlipemia. The nephrotic syndrome may occur as a phase of classical glomerulonephritis or as part of certain systemic diseases not primary in the kidney. However, there is compelling evidence to support the belief that in children the nephrotic syndrome may, and almost always does, occur as a disease of unknown etiology but distinct from the glomerulonephritis associated with infection by the hemolytic streptococcus. The fact that the mortality rate does not change abruptly from childhood to adulthood suggests that apart from those few cases occurring as a stage of glomerulonephritis or as a part of certain systemic diseases, the nephrotic syndrome represents the same disease in adults as in children. Proteinuria in patients with the nephrotic syndrome is attributed to an alteration in the glomerular membrane which permits large amounts of protein to pass into the glomerular fluid, and the primary cause of hypoproteinemia is ascribed to urinary excretion of protein. In patients with the nephrotic syndrome, the concentration in serum of the low density beta lipoproteins rich in triglycerides, cholesterol, and phospholipids is usually increased. The cause of these alterations is not known, but recent evidence suggests that they may be related to the urinary loss of plasma albumin. Edema in patients with the nephrotic syndrome is due to renal tubular reabsorption of filtered sodium chloride and water in excess of that required to maintain a normal volume of extracellular fluid. The question of whether the primary alteration is a reduction in glomerular filtration rate or an increase in tubular reabsorption has not been resolved. A review of the course of patients with the nephrotic syndrome emphasizes the chronic nature of the disease. The median time from onset to recovery varied from 22 to 57 months in different age groups, with great variability within groups. In the group of patients who died, the median time from onset to death ranged from 29 to 82 months. The corrected mortality was slightly over 40 per cent in the group of patients under 10 years of age and increased with age to 86 per cent in patients over 30 years of age. Although general measures in treatment are of great practical importance, of greater significance at the present time are the problems concerning the use of corticotropin or adrenocortical steroids. Present evidence suggests that these agents should be used to induce diuresis and that they should be given for a prolonged period thereafter.