When blood gets into a person's urine (pee), doctors call it hematuria (hee-ma-TUR-ee-uh). Hematuria is pretty common, and most of the time it's not serious.
Peeing is one way our bodies get 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 we pee it out. If blood cells leak into the urine at any part of the process, it causes hematuria.
There are two kinds of hematuria:
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 may sound nasty, but it's usually not — in medicine, "gross" is just a word that describes when something is large or happens in bigger amounts. Gross hematuria just means that enough red blood cells are in a person's urine to turn it red or tea-colored. Like microscopic hematuria, gross hematuria often clears up on its own with no problems. Sometimes, though, it can be a sign of a more serious condition.
Teens can get hematuria for many reasons. The more common causes are:
bladder or kidney infections
defects in the structure of the urinary tract
mineral imbalances in the urine, like too much calcium
taking certain medicines, like some over-the-counter pain relievers
Other reasons why teens get hematuria are menstruation, vigorous exercise, and injuries to the kidneys or urinary tract. 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 will usually be one of many other symptoms.
Very occasionally, what looks like hematuria might be something else. It's possible (though unlikely) that things like food dye, some foods (like beets or blackberries), or certain prescription medicines can make a person's urine look red.
If you ever see blood in your urine, don't panic. Chances are, it's no big deal. But you'll want to be sure, so tell your mom or dad and see a doctor. If you need treatment, it's good to get started right away.
If you see a doctor about blood in your urine or if microscopic hematuria shows up on a urine test, the doctor will give you a physical examination. He or she will ask you and your parent questions about recent activities and family medical history. You'll probably need to provide a urine sample, which means peeing in a cup.
If the urine test comes back negative, the doctor will probably want another urine sample 1-2 weeks later to make sure the urine is free of red blood cells. If hematuria only happens once, there's usually no need for any treatment.
What if tests show you have microscopic hematuria? If you don't have any symptoms like pain or fever, you haven't had a recent injury, and there's no protein in your urine, your doctor will do more urine tests over a few months to see if you still have blood in your urine.
If urine samples point to something more serious or you've had a recent injury, you'll probably need additional tests, such as a urine culture (more peeing in a cup!), or imaging tests like a kidney ultrasound, an MRI, or a CT scan. Occasionally, doctors need to remove a tiny piece of kidney tissue for testing (biopsy) or use instruments to check inside the body.
Most teens who have hematuria won't need any kind of treatment for it. 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 yearly after that as a precaution. Hematuria that is due to an infection will be treated with antibiotics.
If you've been treated for hematuria, your doctor will probably want you to get follow-up tests to make sure your urine is free of red blood cells. If the hematuria goes away, your doctor may still want to check your pee once a year.
When hematuria is a sign of something more serious — like kidney stones or a specific kidney disease — doctors will treat that condition.