When blood gets into urine (pee), it's known as hematuria (hee-ma-TUR-ee-uh). Hematuria is pretty common, and most of the time it's not serious.
Peeing is one way the body gets rid of waste products. The process starts in the kidneys, which remove excess fluids and waste from the blood and turn them into urine. The urine then flows through tubes called ureters into the bladder, where it's stored until it's peed out. If blood cells leak into the urine at any part of the process, it causes hematuria.
The two kinds of hematuria are:
Microscopic hematuria is when blood in the urine is invisible to the naked eye; it only shows up under a microscope. In many cases, microscopic hematuria goes away without causing any problems. In fact, people might never know they have it unless they get a urine test.
Gross hematuria is when you can see the blood in the urine. This is because there are enough red blood cells in the urine to turn it red or tea-colored. Gross hematuria usually goes away on its own with no problems, but sometimes it's a sign of a more serious condition. In those cases, doctors will treat the underlying cause.
A person can get hematuria for many reasons. The more common causes are:
taking certain medicines, like some over-the-counter pain relievers
vigorous exercise (many athletes, especially distance runners, get hematuria from time to time)
In rare cases in children, hematuria can be a sign of kidney cancer or bladder cancer, a blood disease, or a blood clot. If something like that is going on, hematuria usually will be one of many other symptoms.
Very occasionally, what looks like hematuria might be something else. It's possible for things like food dye, some foods (like beets or blackberries), or certain prescription medicines to make a person's urine look red.
Signs & Symptoms
Technically speaking, hematuria is a symptom. Microscopic hematuria has no visible signs. Doctors will only know someone has it if a urine test finds it. Gross hematuria can be seen because it changes the color of urine, which can happen with just a little bit of blood. In many cases, red or tea-colored urine is the only symptom.
In more serious cases, hematuria can be just one of many symptoms of another condition. For instance, if a bladder infection is causing the hematuria, other symptoms might include fever, pain while peeing, and lower belly pain.
If you ever see blood in your child's urine, don't panic. Chances are it's no big deal. But you'll want to make sure, so take your child to see a doctor. It's important to find the cause in case any treatment is needed.
The doctor will do a physical exam and ask about symptoms, recent activities, and family medical history. Your child will give a urine sample for testing. If the urine test comes back negative, the doctor probably will do another test 1-2 weeks later, just to make sure the urine is free of red blood cells. Hematuria that only happens once won't require any follow-up with the doctor.
If your child has microscopic hematuria with no other symptoms (like pain or fever) and no protein in the urine, the doctor will do more urine tests over a few months to see if there's still blood in the urine.
If test results point to something more serious, or if your child has had a recent injury, more tests might be done. These can include a urine culture, or imaging tests like a kidney ultrasound, MRI, or CT scan that let doctors examine the urinary tract.
When to See a Specialist (Nephrologist)
Kids who have hematuria and protein in the urine should see a nephrologist (a doctor who specializes in kidney care). So should kids with microscopic hematuria that doesn't go away after a few months, or who have microscopic hematuria and high blood pressure and other symptoms.
Additional testing can help find the cause of blood in the urine. Tests may include:
blood tests to check kidney function
urine tests to look for protein, calcium, and creatinine (a waste product found in urine)
kidney biopsy (removing a tiny sample of tissue for testing)
cystoscopy (a procedure done by a urologist, who uses a thin, tube-like instrument with a tiny camera on the end to see the inside of the urethra and bladder)
Most of the time, hematuria doesn't need any treatment. If it only happens once, it's nothing to worry about.
Those who get blood in their urine more than once but have no other signs of illness may need urine tests and physical exams every few months for a year and then yearly after that as a precaution.
If another condition is causing the hematuria, doctors will treat that condition. For instance, hematuria that is due to a urinary tract infection (UTI) will be treated with antibiotics.
If your child has been treated for hematuria, the doctor probably will want to do follow-up tests to make sure your child's urine is free of red blood cells.