If a lot of protein is found in your child's urine, a more serious kidney disease might be the problem. Proteinuria doesn't cause pain. But when a lot of protein is in the urine, the level of protein in the blood may go down. This can cause swelling in your child's eyelids, ankles and legs. High blood pressure is another sign of this problem.
Orthostatic proteinuria occurs in some older children and teenagers.
Children with this condition have no kidney damage but, for some unknown reason, they lose protein into the urine during the day when they are active. At night, while they sleep, their kidneys don't let any protein into the urine. Your doctor diagnoses this harmless condition by checking two urine samples. The first one is collected in the morning, right after your child gets up, and it's kept in one container. If your child has orthostatic proteinuria, the morning sample won't have protein in it.