The result is edema and hypovolemia, which stimulates tubular reabsorption of sodium and water to increase intravascular volume. These pathologic processes and others that are less well understood bring about the symptoms of nephrotic syndrome. The first sign noted is usually swelling about the eyes on rising in the morning that subsides during the day. As edema worsens there is a gradual weight gain, which parents may mistake for healthy growth. The fluid shift progresses and eventually causes abdominal swelling from ascites, respiratory difficulty from pleural effusion, and generalized edema.
Intestinal edema can cause diarrhea and anorexia.
A diminished output of dark, frothy urine also occurs. Laboratory analyses of urine and blood reveal proteinuria, elevated specific gravity of the urine, decreased serum proteins, and elevated serum cholesterol levels. Renal biopsy and the appearance of renal tissue under microscopic examination can establish the diagnosis and identify the type of nephrotic syndrome present. Corticosteroid therapy is gradually decreased until the urine is free of proteins and edema subsides. About 80 per cent of children with nephrosis have a favorable prognosis.