When should you worry about blood in your urine?

Patients should consult their doctor if they detect blood in their urine.
Blood in your urine may be a symptom of a serious health problem, including cancer, so it’s important to determine the cause as quickly as possible.

Seeing blood in your urine would scare just about anyone. Although many causes for the bleeding are typically treatable, you shouldn’t ignore it—even if it’s only a small amount of blood and it goes away. Bloody urine may be a symptom of a serious health problem, including cancer, so it’s important to determine the cause as quickly as possible.

Blood in the urine, clinically known as hematuria, is caused when red blood cells from the kidneys, ureters, bladder or urethra have entered the urine stream.

Hematuria is clinically classified as either:

  • Gross, or visible while urinating or in the toilet water
  • Microscopic, or detected only through a urine test or under a microscope

Too often, patients go to the emergency room with visible, painless signs of blood in their urine that’s misdiagnosed as a urinary tract infection (UTI) and treated with an antibiotic.

“This is terribly, catastrophically common,” says Farshid Sadeghi, MD, Medical Director of the Genitourinary Center at City of Hope Phoenix. “If it’s a UTI, there should be pain, there should be discomfort, there should be changes in urination, not just blood in the urine alone.”

Is blood in the urine always cancer? No. But cancer is always a concern with painless, gross hematuria, says Dr. Sadeghi. And that’s why it must be properly evaluated.

In this article, we’ll explore the causes of blood in the urine, including which types of cancer may cause the condition. Topics include:

If you’ve been diagnosed with bladder or kidney cancer and are interested in a second opinion on your diagnosis and treatment plan, call us or chat online with a member of our team.

What may cause blood in the urine

Numerous medical conditions may cause blood in the urine, and they’re typically treatable or pass on their own. These include:

Bladder or kidney stones: Bladder and kidney stones develop when minerals concentrate in the urine and form crystals on the walls of the bladder or kidneys. These stones may be painful, but they don’t always come with symptoms unless they cause a blockage or are being passed. Stones may cause both gross and microscopic bleeding.

Enlarged prostate: This condition naturally occurs as men begin to age, and it may compress the urethra, partially blocking the flow of urine and causing both gross and microscopic bleeding, in addition to difficulty urinating and a persistent or urgent need to urinate.

Inherited disorders: Conditions like hemophilia and sickle cell anemia, which affect hemoglobin—the protein responsible for transporting oxygen—may cause blood in the urine that’s both gross and microscopic. Other symptoms may include dizziness, fatigue and jaundice.

Kidney disease: This condition is often caused by diabetes, infections or a compromised immune system. Other symptoms include changes in the frequency, color or consistency of urine; swelling in the limbs; anemia; a rash and severe itching; and nausea and vomiting.

Kidney infections (pyelonephritis): These infections develop when bacteria travel to the kidneys from the bloodstream or from the ureters to the kidneys. Kidney infections may cause symptoms similar to UTIs, but they may also commonly cause a fever, flank pain, nausea and vomiting.

Kidney injury: An injury to the kidneys, such as a blow during a sports game, may cause gross bleeding in the urine. A kidney injury may also cause a fever, pain and swelling in the abdomen, and nausea and vomiting.

Urinary tract infections: UTIs develop when bacteria enter the body through the urethra and multiply in the bladder. Other symptoms may include a strong need to urinate, pain and burning while urinating, and strong-smelling urine.

Other factors that may cause blood—or the appearance of blood—in the urine, include:

Medications: Blood thinners may cause blood in the urine—as may aspirin, penicillin and the chemotherapy drug cyclophosphamide.

Foods: Certain foods, like beets and rhubarb, may temporarily give urine a pink or red hue when eaten in excess.

Strenuous exercise: Visible blood in the urine is rare with exercise, but it may occur with intense workouts, especially long-distance running. It was likely caused by trauma to the bladder, dehydration or the breakdown of red blood cells.

Surgery: Procedures that involve catheterization or surgery on the urinary tract may cause blood in the urine.

It’s worth noting that, in women, menstrual blood may also sometimes be mistaken for blood in the urine.

Why painless blood is cause for concern

Painless, visible blood in the urine requires a urologic evaluation following a two-part process:

  • Imaging, such as a CT scan, that examines the lining of the upper urinary tract and ureters.
  • Cystoscopy, a procedure that uses a scope and a camera to examine the bladder and urethra

“Many patients protest that if their bladder looks clear on imaging, they shouldn’t need the cystoscopy, but the scan may miss signs of cancer, which is why the cystoscopy is non-negotiable,” Dr. Sadeghi says.

Fortunately, the cystoscopy isn’t as scary as many people expect it to be. The local anesthetic is a gel, not an injection, and the procedure itself takes two to three minutes. Patients are also able to comfortably walk out of the procedure when it’s finished. “Patients are often very worried about the cystoscopy, but I’ve performed thousands of them, and I can tell you that 99.99 percent of patients tell me afterward that it’s not as bad as they feared,” he says.

Microscopic hematuria without also requires a urologic evaluation.  The evaluation may be initiated by a primary care physician and handed off to a urologist.

And, contrary to what some think, visible or microscopic blood in the urine with bladder pain is actually less concerning than blood without pain. That’s because the painful kind was likely caused by something less serious than cancer, such as a UTI.

Blood in the urine and cancer

The most common cancers that may produce blood in the urine include:

Bladder cancer

In most cases, hematuria is the first sign of bladder cancer. It may change the urine to orange or pink and, less commonly, dark red. With bladder cancer, blood may appear in the urine one day and disappear the next, but it always reappears eventually. “The No. 1 way bladder cancer is diagnosed is through visible, painless blood in the urine,” Dr. Sadeghi says.

Hematuria may indicate the early stages of bladder cancer and is most often painless. Other symptoms of bladder cancer that tend to appear after hematuria include changes in urination, such as:

  • A strong and persistent need to urinate
  • Pain or burning during urination
  • Trouble urinating

Kidney cancer

Blood in the urine—usually appearing as rusty or dark red—is the most common symptom of kidney cancer. But the disease may also include symptoms such as:

  • Anemia
  • Low back pain on one side that’s not caused by injury
  • Unexplained weight loss

Because smoking increases the risk of bladder and kidney cancer, smokers who have microscopic hematuria without pain must undergo more careful evaluation than their non-smoking counterparts. If someone who doesn’t smoke is found to have microscopic blood in their urine, a urologist wouldn’t order a full exam unless the blood showed up on three different occasions, Dr. Sadeghi says. Someone who smokes would be referred after a single occurrence.  

Prostate cancer

Blood may also appear in the urine of patients with advanced prostate cancer.

Because of the concern about a possible cancer diagnosis, hematuria, especially the painless kind you can see, must always be taken seriously, Dr. Sadeghi says.

“If you have painless blood in the urine you can see, you must visit a urologist,” he says. “There‘s no way around it. The condition can’t be diagnosed by a primary care physician. And if you go to the ER and they send you home with an antibiotic for a UTI, you need to call your PCP and say you need to see a urologist.”

If you’ve been diagnosed with bladder or kidney cancer and are interested in a second opinion on your diagnosis and treatment plan, call us or chat online with a member of our team.