Nephrotic syndrome refers to a group of symptoms with heavy protein in the urine, low protein level in the blood and swelling of the face, legs and abdomen. Children with nephrotic syndrome essentially have leaky kidneys that constantly lose protein into the urine. The amount of protein lost in the urine has to be large enough to cause low protein in the blood and subsequent swelling. Children with nephrotic syndrome can have significant weight gain because of fluid retention throughout the tissues.
Nephrotic syndrome develops when there is damage to the glomeruli, the structures in the kidneys that filter and "clean" the blood. It can be in variable forms caused by many different mechanisms. Most are still poorly understood. There is a particular condition called minimal change disease which is by far the most common form of nephrotic syndrome in toddlers and school-age children. Infants, older children or adolescents with nephrotic syndrome tend to have different forms. Some are related to congenital defect of the glomeruli, especially for infants.
Children with nephrotic syndrome usually require minimal blood and urine tests on initial presentation. Once a diagnosis is established, they only need a simple urine study called urine dipstick that can be easily done at home. In some cases, a kidney biopsy may be required to help with diagnosis and guide treatments.
The vast majority of children with nephrotic syndrome are treated with corticosteroid medications (like prednisone) and within 2-4 weeks achieve full remission. Remission means urine protein becomes normal and puffiness resolves. Over time the corticosteroid medication is weaned off; however, some patients will have relapses. The timing and frequency of these vary greatly from child to child. As a result, each family will be taught to check their child’s urine for protein at home. Periodic testing will allow early detection of relapses and early treatment before puffiness occurs.
Children that develop side effects related to frequent corticosteroid prescription or those that do not respond to corticosteroid with remission will require alternative treatment. Your pediatric nephrologist will discuss options with you.