UTI or Cancer: What To Know About Blood in the Urine

MSK surgeon and urologic cancer specialist Eugene Pietzak

Surgeon and urologic cancer specialist Eugene Pietzak says anyone who detects blood in the urine should notify their primary care doctor or a urologist to investigate it further.

  • Blood in the urine can be a sign of infection, kidney stones, or cancer, especially bladder cancer.
  • Anyone with blood in their urine should have a doctor investigate the cause.

Blood in the urine, also called hematuria, is a sure sign that something is wrong. But it can be hard to tell what caused this symptom. Is it just a urinary tract infection (UTI), which can be treated with antibiotics, or something more serious, like cancer?

Here’s what you should know about blood in the urine — and why you should never ignore it.

Two Types of Blood in the Urine

The two types of blood in the urine (hematuria) are:

  • Gross hematuria — when the blood is visible. It may be very faint with a pink tinge, or the blood may be obvious. The color comes from hemoglobin in red blood cells. The blood may not be present in the urine all the time — it may come and go.
  • Microscopic hematuria — the urine appears normal, but an increased number of red blood cells can be seen under a microscope. This symptom may show up on a urine analysis you would have as part of an annual physical or any standard checkup.

What Causes Blood in the Urine?

There are several possible causes for this symptom, explains Memorial Sloan Kettering Cancer Center (MSK) surgeon and urologic cancer specialist Eugene Pietzak.

  • Urinary tract infections. UTIs are more common in women than men, explains Dr. Pietzak, because a woman’s urethra (the tube from the bladder to where the urine comes out of the body) is shorter than a man’s. This makes it easier for bacteria to get into the bladder or kidney. Occasionally, a UTI can cause an increase of white blood cells in the urine, a condition known as pyuria. This can cause the urine to appear cloudy, but it is not what most people think of as “blood in the urine.”
  • Bladder or kidney stones. Solid masses that form from chemicals in the urine might scrape the lining of the bladder or kidney and damage blood vessels, causing them to leak.
  • Cancer of the bladder, kidney, or prostate. “A tumor may grow, and the blood vessels within it become fragile so that they rupture and bleed,” Dr. Pietzak says. “I’ve heard people tell vivid stories of having normal urine and then suddenly it becomes completely red.”
    • Often, the person has had no other symptoms before the blood appears. The most likely cancer is bladder cancer, although the blood also could be a sign or kidney cancer (renal cell cancer) or prostate cancer.
    • Blood in the urine is more likely to be cancer in men than in women, mainly because men develop bladder cancer at a much higher rate — about four times as much — than women. Unfortunately, this often leads women (and their doctors) to dismiss this cancer warning sign when the disease is at an early stage.
  • Other causes of blood in the urine. Other causes may include an enlarged prostate, kidney injury, certain medications, or vigorous exercise.

What To Do if There Is Blood in Your Urine

Whether it is gross hematuria or microscopic hematuria, you should not ignore it, Dr. Pietzak emphasizes. Notify your primary care doctor, who can refer you to a urologist for a more thorough evaluation. The primary care doctor or urologist will order tests to help determine whether it is a UTI. This involves examining urine under a microscope for bacteria or white blood cells, which are signs of infection. A urine culture may also be taken to detect and identify bacteria and yeast in the urine.

Any visible blood in the urine is abnormal.
Eugene Pietzak surgeon and urologic cancer specialist

When Blood in the Urine Means UTI

If a UTI is detected, antibiotics are usually the first treatment and are effective at clearing up the infection.

When Blood in the Urine Means Cancer

If no UTI is detected, the doctor may do a test called a urine cytology, which checks for cancer cells. “If it comes back positive or suspicious for cancer cells in the urine, that is very concerning,” Dr. Pietzak says. Patients also may have an imaging test, such as a CT, an ultrasound, or an MRI to look for abnormal growths in the bladder or kidney.

If you notice blood in the urine yourself, do not delay getting it checked out, even if it seems to go away.

“Any visible blood in the urine is abnormal,” Dr. Pietzak says. “In the cancer patients we treat, we often hear horror stories where someone noticed blood and even the primary care doctor was notified but no lab workup or evaluation was done for a long time. If someone does have bladder cancer, the earlier it is detected, the less intense the treatment needs to be.”

If you have cancer, Dr. Pietzak recommends treatment at a specialized cancer center such as MSK. “We have various treatment options and clinical trials that aren’t available at most places,” he says. “This allows us to tailor our care to the individual patients. We also have an active research program that is trying to understand the biology of cancer. This includes looking at mutations in urine to make it easier to diagnose what’s happening — including whether the blood in the urine is from cancer or another cause.”