Nephrotic Syndrome

Nephrotic syndrome (NS) is a condition that is often caused by any of a group of diseases that damage the kidneys' filtering system, the glomeruli. The structure of the glomeruli prevents most protein from getting filtered through into the urine. Normally, a person loses less than 150 mg of protein in the urine in a 24-hour period. Nephrotic-range proteinuria, the urination of more than 3.5 grams of protein during a 24-hour period, or 25 times the normal amount, is the primary indicator of NS.

Causes

Nephrotic syndrome can be caused any disease that causes inflammation of the glomeruli. These types of diseases are called glomerulopathies. Minimal change disease (MCD) is the most common cause of nephrotic syndrome in children, and is usually mild. In other cases, the cause appears to be a malfunction of the immune system, which could result from a virus or autoimmune disorder such as systemic lupus erythematosus. The immune system produces infection-fighting proteins, called antibodies, that attack the glomeruli. Other causes of nephrotic syndrome include certain cancers, diabetes, allergic reactions to insect bites or poisonous plants, allergic reactions to drugs such as intravenous heroine and nonsteroidal anti-inflammatory drugs, and infectious illnesses such as hepatitis B and HIV.

Signs and symptoms

The following are the most common symptoms of nephrotic syndrome. However, each child may experience symptoms differently. Symptoms may include:

• fatigue and malaise
• decreased appetite
• weight gain and facial swelling
• abdominal swelling or pain
• foamy urine
• fluid accumulation in the body spaces (edema)
• pale fingernail beds
• dull hair
• ears cartilage may feel less firm
• food intolerances or allergies

The symptoms of nephrotic syndrome may resemble other conditions and medical problems. Always consult your child's physician for a diagnosis.

Diagnosis

Consistent proteinuria in excess of 3.5 g/24 hours strongly suggests NS; examination of urine also reveals an increased number of hyaline, granular, and waxy, fatty casts, and oval fat bodies. Serum values that support the diagnosis are increased cholesterol, phospholipids, and triglycerides and decreased albumin levels. Histologic identification of the lesion requires a kidney biopsy.

Treatment

Effective treatment of NS necessitates correction of the underlying cause if possible. Supportive treatment consists of protein replacement with a nutritional diet of 1.5 g protein/kg of body weight, with restricted sodium intake; diuretics for edema; and antibiotics for infection.

Some patients respond to an 8-week course of corticosteroid therapy (such as prednisone), followed by a maintenance dose. Others respond better to a combination course of prednisone and azathioprine or cyclophosphamide.

Prevention

Treatment of causative disorders may prevent development of nephrotic syndrome.