What is hematuria?
Hematuria means that red blood cells are in the urine. Urine does not normally contain red blood cells because the filters in the kidney prevent blood from entering the urine. In hematuria, the filters or other parts of the urinary tract allow blood to leak into the urine. Microscopic hematuria means that the blood is detected only with a microscope, while gross hematuria means the urine appears red or the color of tea or cola. Microscopic hematuria in an otherwise healthy child does not usually need to be investigated unless it is present in at least three urine tests over several months. However, if the child has high blood pressure, chronic kidney disease or protein in the urine, then hematuria should be investigated promptly
What causes hematuria?
Hematuria is a common finding in children and has more than 100 different causes. These causes may include:
- abnormal structures in the urinary tract
- inherited diseases
- mineral imbalances in the urine
- in some cases, no cause of hematuria may be found.
Structural Causes of Hematuria
Kidneys that contain cysts (fluid-filled sacs) or are blocked may lead to any type of hematuria. An ultrasound of the kidney can determine if an abnormal structure is causing blood in the urine.
Inherited Causes of Hematuria
Several different diseases that run in families can cause hematuria. These include polycystic kidney disease, Alport's syndrome, inherited nephritis and sickle cell disease in the African-American population.
Mineral Imbalances in the Urine
High levels of calcium in the urine can cause hematuria. The hematuria may be painless or associated with pain in the area of the kidney and/or a burning feeling during urination. Children with high levels of calcium in the urine are more likely to have a family member with a history of kidney stones. Children who have this condition have a higher risk for the development of a kidney stone, but less than 10-15 percent actually develop a stone. Most children with microscopic hematuria do not need treatment unless they have developed a kidney stone. It is important not to reduce dietary calcium in children who have high levels of calcium in their urine. The risk of developing kidney stones later is less than the risk of not depositing enough calcium in the skeleton in growing children.
Glomerulonephritis is a common cause of blood in the urine. There are many types of glomerulonephritis. Some of these are mild and resolve on their own, while others are more severe and require medication. Blood tests can suggest some kinds of glomerulonephritis, but in some cases, a kidney biopsy may be needed to find the exact form of the disease. For more information about the different forms of glomerulonephritis, consult the National Kidney Foundation's publications on glomerulonephritis.
"Idiopathic" means that no specific cause can be found for blood in the urine. Idiopathic hematuria can run in families, and then it is called familial idiopathic hematuria. When there is not a family history of kidney failure and other medical tests are negative, usually no treatment is needed.
How is hematuria evaluated?
Children who have microscopic hematuria with normal blood pressure and kidney function should have their urine checked over several months. If blood in the urine continues:
- A kidney ultrasound may be performed
- Urine should be checked for protein and may be checked for calcium and creatinine.
- Blood test to determine kidney function and other tests may be performed.
- If all tests are negative and blood remains in the urine, yearly checkups should be done.
Children who have microscopic hematuria with high blood pressure, abnormal blood tests, a family history of kidney disease or high levels of protein in the urine may need to have a kidney biopsy.
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© 2015 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.