Childhood Nephrotic Syndrome
Nephrotic syndrome is also called nephrosis. These two terms describe a condition in which the kidneys leak large and abnormal amounts of protein into the urine. When protein is lost in the urine, this leads to puffiness or swelling (edema), often of the eyelids, feet and ankles, and eventually the abdomen. If left untreated, this can lead to problems with breathing, eating and infections.
Nephrotic syndrome is diagnosed by recognizing three findings:
- Swelling (edema)
- High levels of protein in the urine (proteinuria), and
- Low levels of protein (albumin) in the blood (hypoalbuminemia)
The onset or first "attack" of nephrotic syndrome can be a disturbing experience for parents and for the child. Because the swelling tends to develop slowly, it may not be recognized right away. By the time a diagnosis is made by a doctor, a child may be very swollen and may need to be hospitalized. Most children respond very well to treatment of nephrotic syndrome and, although most children have further attacks of the disease, the long-term prognosis for most children is very good.
Who is affected?
Childhood nephrotic syndrome can start at any age, but usually begins between the ages of two and five years. It is a rare condition that affects about 16 out of every 100,000 children at any given time, and it affects more boys than girls. It is extremely unlikely that other children in a family will also have nephrotic syndrome. While there are a few types of nephrotic syndrome which do run in families, these are very rare.
Causes of Childhood Nephrotic Syndrome
The exact cause of nephrotic syndrome is not known and it cannot be prevented. However, research into this condition is ongoing and researchers are trying to develop increasingly effective treatments. What we do know is that nephrotic syndrome is usually caused by an imbalance, from time to time, of the body’s immune system. This imbalance causes certain chemicals to disturb the filters of the kidneys. These filters begin to allow proteins to leak into the urine.
All the successful treatments for nephrotic syndrome work on the immune system in some way. Many, but not all, attacks of nephrotic syndrome are brought on by something that stimulates the immune system, such as a cold, flu or other infection.
Treatment for Childhood Nephrotic Syndrome
When a child is first diagnosed with nephrotic syndrome, the doctors will usually prescribe steroid drugs such as prednisone or prednisolone. The kinds of steroids used to treat nephrotic syndrome are not the same as the anabolic steroids that are sometimes abused by athletes.
Most children respond very well to steroid drug treatment. Usually, within one to two weeks the protein in the urine disappears and the swelling in the tissues goes away. This stage is called remission. A child that responds to steroids (steroid sensitive nephrotic syndrome) by going into remission is usually thought to have a clinical diagnosis of minimal change disease. Minimal change disease usually has a good prognosis.
There is a very small group of children who do not respond to steroid treatment (steroid resistant nephrotic syndrome), who continue to have lots of protein leaking into their urine, or who show serious adverse effects from prednisone. These children may require other treatments prescribed by their nephrologist.
Relapses and remissions
Most children will have at least one relapse or recurrence of protein in the urine. Each relapse will need a further course of steroid treatment. In general, steroid treatment for a relapse is for a shorter time than the initial treatment at the time of diagnosis of nephrotic syndrome. If a child has fairly frequent relapses then they might take a small dose of steroid medication on alternate days to prevent relapses. This is usually called maintenance treatment. However, as the child becomes older, the relapses usually happen less often.
It is not possible to accurately predict when the relapses will stop, but it is uncommon to have relapses after adolescence. It is also uncommon to have a relapse after the child has been free of protein in the urine (in remission) for five years.
It is important to remember that children with the usual type of nephrotic syndrome (minimal change disease) have no risk of kidney failure. Usually, as a child grows older, the nephrotic syndrome will become less troublesome. The great majority of children will eventually outgrow the problem and become teenagers and adults with normally functioning kidneys.
Adapted from Childhood Nephrotic Syndrome: A guide for parents on the management and treatment of Childhood Nephrotic Syndrome, The Kidney Foundation of Canada © 2007