Causes of blood in a child's urine, also known as hematuria, include cysts or other blockages in the urinary tract, mineral imbalances, diseases that impede the filtration of blood in the kidneys, and inherited kidney diseases, reports the National Kidney Foundation. Doctors are sometimes unable to isolate the cause of the hematuria. Bladder and kidney infections also may cause blood in children's urine, adds WebMD.
Doctors use ultrasound to find out if cysts or other abnormal structures are blocking kidneys, explains NKF. Pain in the kidney area or burning urination may accompany hematuria if a child has a high percentage of calcium in his blood. This may result from a genetic propensity toward kidney stones, but the child should continue to imbibe dietary calcium to ensure strong skeletal structures.
Diseases called glomerulonephritis that block the kidneys from filtering blood can be acute or chronic, according to NKF. The acute form comes on suddenly, often after a throat or skin infection, and symptoms may be mild to severe. The chronic form develops slowly, often without symptoms until blood shows in the urine, and can lead to kidney failure. Hematuria is a symptom of inherited kidney diseases such as nephritis, Alport's syndrome, polycystic kidney disease and sickle cell disease. Methods to determine the cause of hematuria in children include blood tests, urinalysis and biopsies.