Am Fam Physician. 2010;82(6):652
See related article on proteinuria
What is proteinuria?
The kidneys remove waste from the blood. This waste leaves the body in urine. Usually, proteins are too big to go through the kidneys and into the urine. But sometimes, protein can leak into the urine. This is called proteinuria.
Proteinuria is usually harmless. However, it can be caused by kidney problems, such as infection or chemicals that can damage the kidneys.
How do I know if my child has it?
Your doctor may test your child's urine to measure how much protein is in it. He or she may also do blood tests.
If there is only a little protein in the urine, your child probably has a harmless kind of proteinuria. A lot of protein may be a sign of a more serious kidney problem and can cause swelling or high blood pressure.
What are the different kinds?
Most children have transient or orthostatic proteinuria. These kinds aren't caused by kidney problems and usually don't cause symptoms.
Transient proteinuria is most common. It is temporary and can be caused by fever, stress, dehydration, exercise, or exposure to cold temperatures.
Orthostatic proteinuria happens in some older children and teenagers. It causes protein to go into the urine only when the child is standing up. The cause is unknown.
How is it treated?
If your child has a small amount of protein in the urine, no treatment is needed. The doctor may check your child's urine again after a few months. If the amount of protein in the urine doesn't change or goes up, your child may need to see a kidney specialist called a nephrologist. The nephrologist may do more testing, like examining a small piece of your child's kidney, to find out what is causing the proteinuria. He or she can then treat the cause.
Eating less salt and taking medicine can reduce any swelling caused by proteinuria. It's also important that your child visits the doctor for regular checkups. It's okay for your child to do normal activities.