What causes blood in urine?

DEAR DOCTOR K:

My doctor did a urine test and says I have hematuria. What is this? And what could have caused it?

DEAR READER:

Hematuria is the presence of red blood cells in the urine. It means there is bleeding somewhere in your kidneys, your prostate (if you’re a man) or your bladder. If there are a lot of red blood cells, you will see them: They will turn your urine pink or red. If there are only a small number of red blood cells, you won’t see them, but they will show up when the doctor looks at your urine under the microscope.

There are many possible causes of hematuria. Usually they are not serious problems, but sometimes they are very serious. So doctors always try to find what’s causing the hematuria.

  • Strenuous exercise can produce blood in the urine, believe it or not. You won’t usually see it, but if you go to your doctor for a checkup right after exercising, blood may show up in your urine. This is harmless.
  • Urinary tract infection in your bladder or kidney often causes hematuria, although it’s the pain with urination and having to go frequently, not a change in urine color, which is the most common reason that people call the doctor.
  • Kidney stones can form inside the kidney and get stuck there or in the tubes draining the kidney, causing bleeding. Some kidney stones cause severe pain, but some stones are “silent” — with hematuria being the only clue they are there.
  • Traumatic injury to any part of the urinary tract often causes hematuria. I had one teenage patient who had hematuria after being hit hard in the back during a football game.
  • Bleeding disorders such as hemophilia can cause hematuria.
  • Blood thinners can cause hematuria.
  • Glomerulonephritis, a family of diseases that damage the filtering units of the kidneys, can cause red blood cells to leak out of the kidney.
  • Tumors in the kidney or bladder are what we worry about most when we see hematuria.

Depending on your symptoms, there are a number of tests your doctor is likely to order. These include simple tests like a repeat urinalysis, a urine culture (to look for bacterial infection), or blood tests to check for signs of infection, kidney failure, anemia, bleeding disorders or conditions that lead to kidney stones.

The tests may be more complicated, such as a CT scan or an ultrasound to take a picture of your kidneys, ureters and bladder. The most complicated test is a cystoscopy, in which you receive anesthesia and have a tube passed into your bladder to look for tumors or other causes of bleeding.

Finally, you should know about a surprisingly common condition that turns your blood pink or red but is not hematuria. It’s called “beeturia.” If you eat beets, the red coloration in the beets can briefly turn your urine red and scare you half to death, but it’s nothing to worry about.

Related Information: Harvard Men’s Health Watch