| Hematuria refers to blood in the urine. Often, if a child complains of painful urination or abdominal pain, his doctor may want to test the child's urine using a paper test strip. This is known as a dipstick urinalysis.
One of the tests that can be performed with these test strips is a test for blood. Sometimes the blood is obvious like a clot and this is called gross hematuria. It is important to always test the urine even when it appears red because not all obviously red urine has blood in it. For example, certain foods like beets and certain medicines like metronidazole (an antibiotic) can make the urine turn red.
Other times the amount of blood is invisible to the naked eye and is called microscopic hematuria. Microscopic hematuria without other symptoms, such as edema or swelling, high blood pressure, renal insufficiency or proteinuria (protein in the urine), is very common and occurs in almost 2% of children. Since it is so common, your Pediatrician may just repeat the urine test in a few weeks or months to see if it goes away on its own (unless the hematuria is gross or your child has other symptoms or clinical findings).
In either case, whether microscopic or gross, there are a lot of reasons why a person can get blood in her urine. In addition to a microscopic examination of the urine as described below, other tests may include a complete blood count (CBC), a urine culture, a serum creatinine level (which is a test of how well the kidney is working), a serum C3 level, and a urine test for the level of protein, calcium and creatinine (this urine test may be a 'spot' test on a sample of urine or it may be on a 24 hour urine collection). Further testing depends on what other symptoms a child has and may include further blood tests, a voiding cystourethrogram (VCUG), renal sonogram, cystoscopy, and sometimes a biopsy of the kidney.
One of the most common causes of hematuria is a urinary tract infection or UTI. A culture of the urine to look for bacteria will determine if that is the cause. Other common but harmless conditions are irritation of the urethra, the opening where the urine comes out. Masturbation is another reason. Insertion of a foreign body into the urethra like a catheter and trauma (sometimes minor) are other reasons. Menstrual bleeding should be considered in young girls who have entered puberty. In these conditions sometimes the blood is visible to the naked eye and sometimes it is not. Also, exercise can sometimes cause hematuria and your doctor may test for this by getting a first voided sample in the morning before your child has gotten out of bed.
If the cause of the bleeding is not easily identified, further examination of the urine with a microscope can help sort out the cause. Under the microscope, if the laboratory technician sees whole red blood cells (RBCs) without any distortion of their shape and no clumps of RBCs (called casts), then the cause of the bleeding is from somewhere in the urinary tract outside the kidneys themselves, such as the ureters (the tubes that carry urine from the kidney to the bladder), the bladder or the urethra. Other causes can be kidney stones and excessive calcium and cysteine (an amino acid) in the urine. Doctors can check for kidney stones with an x-ray of the abdomen known as a KUB (which stands for kidneys, ureters, and bladder). They can also determine the amount of calcium and cysteine in the urine by requesting special chemical analyses of the urine. Finally, a sonogram of the kidneys can be helpful to determine if there are any malformations of the kidneys, cysts (fluid filled sacs within the kidney) or tumors that may be the cause of the hematuria.
If the microscopic examination of the urine reveals both misshapen RBCs and casts, then the bleeding is said to be glomerular, or from the kidney. A glomerulus is the filtering body within the kidney. One of the most common causes of this kind of bleeding is post-streptococcal glomerulonephritis. After an infection with some strains of Group A Streptococcus (Streptococcus pyogenes), the bacteria that causes strep throat, the body can develop an immune reaction that causes damages to the glomerular bodies. These strains of streptococcus do not infect the kidney but can infect the throat and the skin. Even if the throat or skin infection was treated with antibiotics, these strains of bacteria can still can an immune reaction that temporarily damages the kidneys. The reaction usually shows up one to three weeks after the throat or skin infection. Other causes of hematuria that result in both RBC casts and misshapen RBCs are Henoch-Schonlein purpura, hemolytic-uremic syndrome, Alport syndrome, and a host of other conditions. These conditions are associated with protein in the urine (proteinuria) as well as hematuria.
Finally microscopic examination of the urine can reveal no RBC casts and few to no intact RBCs. This result is consistent with hemoglobinuria or myoglobinuria. Hemoglobinuria means there is hemoglobin, the protein found in RBCs that gives the red coloring. Myoglobinuria means there is myoglobin, the protein found in muscles. When RBCs or muscle breakdown, these proteins are released into the blood stream where they can then be filtered by the kidneys and go into the urine. Therefore any condition that can cause destruction of red blood cells or muscles can lead to either hemoglobinuria or myoglobinuria.
It is important to remember that there are usually other symptoms associated with the most serious causes of hematuria, such as swelling or edema and/or high blood pressure.
The cause of hematuria usually can be identified from the information the patient (or in the case of children, their parents or caregivers) supply the doctor as well as the physical exam and urinalysis. In about ten to twenty percent of cases, the cause remains unknown and the patient is followed at regular intervals.
Internet Resources:
- National Kidney Foundation: "a major voluntary health organization, seeks to prevent kidney and urinary tract diseases, improve the health and well-being of individuals and families affected by these diseases, and increase the availability of all organs for transplantation."
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