Blood in the Urine

The sight of blood in your urine — the toilet water turned a shade of red — is understandably an alarming one. The good news is that it’s usually not serious. In fact, even something as innocent as exercise can cause it. But there’s a possibility it may also be a symptom of a more serious problem such as cancer, so you should always see a doctor about it.

What is blood in the urine?

Red blood cells (RBCs) in the urine (called hematuria) can be hard to ignore when they turn your toilet bowl pink, bright red, or the color of cola. Intermittent spots of blood in the water may be also be seen. This overt form of blood in the urine is called “gross” or “frank” hematuria. It doesn’t take much blood — or about a fifth of a teaspoon — to turn a half-quart of urine an obvious shade of red.

In other cases, the presence of blood may be so minute that it’s not visible to the eye. This is called microscopic hematuria, and doctors usually detect it during a routine urine test. Sometimes, what you assume to be blood in the urine may be something else altogether: women may mistake menstrual blood for blood originating in the urine; men may confuse blood in the urine with blood in an ejaculation (which usually suggests a prostate problem).

What causes it?

Blood in the urine can have a variety of causes. As a rule, blood visible to the eye is caused by a problem in the lower urinary tract (ureter, bladder, or urethra), and microscopic blood in the urine usually originates in the upper tract (kidneys).

Here’s a list of possible causes:

Kidney and urinary tract problems

  • Kidney stones
  • Urinary tract infection (cystitis) (Along with kidney stones, UTIs are the most common cause of blood in the urine of people under 40)
  • Bladder infection
  • Inflammation of the bladder, urethra, or kidney (called glomerulonephritis)
  • Cancer of the bladder, kidney, or prostate
  • Injury to the upper or lower urinary tract
  • Recent urinary tract procedure, such as catheterization, circumcision, surgery, or kidney biopsy
  • Polycystic kidney disease
  • Prostate gland enlargement
  • Kidney failure (acute or chronic)
  • Kidney disease following strep throat (post-streptococcal glomerulenephritis) a common cause of blood in the urine in children
  • Medications such as antibiotics (rifampin), analgesics (aspirin), phenytoin, quinine, and blood-thinning drugs like warfarin

Blood disorders

  • Hemophilia or other clotting disorders
  • Sickle cell disease
  • A blood clot in the kidneys
  • Low platelet count

The biggest worry with blood in the urine is bladder cancer — the classic patient is an older person who is a smoker and notices blood in his urine but has no other symptoms. These folks need aggressive evaluation.

What should I do?

People with blood in their urine should ALWAYS consult their doctors. If you have a urinary tract infection or a kidney stone, you should drink a lot of water; blood in the urine also means that you should avoid acidic drinks such as coffee, tea, or citrus juices, all of which can irritate the bladder. Depending on the symptoms, a referral to a specialist such as a urologist may be necessary. In addition to blood that may or may not be visible in the toilet, other potential signs of infection may include:

  • Unexplained weight loss
  • Burning sensation when urinating
  • Frequent or urgent urination
  • Fever, nausea, vomiting, shaking chills, or pain in the abdomen, side or back
  • Inability to urinate
  • Passing blood clots through the urine
  • Pain during sex or heavy menstrual bleeding
  • Dribbling urine, excessive nighttime urination, or difficulty starting to urinate

Although these symptoms may be caused by another health problem, you should consult a physician to find out what the problem is and what needs to be done to treat it.

How can I find out what’s causing blood in the urine?

A doctor may order a series of tests to find the cause. These tests may include:

  • Urinalysis, an examination of urine for various cells and chemicals
  • Blood test, an examination of blood to reveal kidney disease
  • Intravenous pyelogram, an x-ray of the urinary tract, which uses a dye to detect a tumor, a kidney or bladder stone, an enlarged prostate, or another blockage of the urine
  • Cystoscopic examination, inserting a tiny camera at the end of a tube into the urethra to gain a better view of a tumor or bladder stone
  • Kidney x-ray, an x-ray to detect kidney abnormalities

Other tests that may be necessary include: urine culture; a 24-hour urine collection to measure creatinine, protein, and calcium levels; a test for strep throat; a test for the blood disease lupus; an abdominal ultrasound; a computerized tomography (CT) scan of the abdomen; a magnetic reasonance imaging, or MRI, of the kidneys and lower urinary tract.

Typically, the patient gets a urinalysis, CT scan, and cystoscopy (done by a urologist). More studies may be added depending on the particular situation and on the findings of these first three studies.

How is blood in the urine treated?

Treatment depends on the cause. In some cases the origin is not serious, and treatment may not be necessary. If the cause is kidney stones, your doctor may tell you to take pain relievers and drink plenty of water to help pass the stone; sometimes surgery to relieve the blockage is needed. For urinary tract infections, your doctor will prescribe antibiotics for up to two weeks. If it’s cancer, early treatment has a chance of a good outcome.

You’ll typically be asked to go in for a follow-up appointment one to two weeks later, when you’ll have your urine tested again. If the problem hasn’t cleared up, your doctor may send you to see a specialist.


American Academy of Family Physicians. Family What is Microscopic Hematuria?

American Kidney Fund. Important Facts about Blood in the Urine.

American Academy of Family Physicians. American Family Physician. Urine Dipstick vs. Urinalysis to Identify UTIs in Women

MedlinePlus. National Kidney and Urologic Diseases Information Clearinghouse. Hematuria: Blood in the Urine.

eMedicineHealth. “Blood in the Urine”

MedlinePlus. National Institutes of Health. “Urine — bloody”

Mayo Clinic. Bladder stones: tests and diagnosis.

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