Blood in Urine

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What causes blood in urine, what should I do if I notice this? Is there a chance it could be cancer?

If You Find Blood in Your Urine - Hematuria

Finding blood in your urine can be a frightening experience. Any time you discover it, it is important to see your doctor. Blood in the urine (hematuria) is a symptom of many diseases and conditions that often require treatment. The good news is that in most cases, cancer is not responsible.

Blood in the urine is more likely to be caused by a minor, treatable condition such as a bladder infection.

If you have found blood in your urine, your doctor will often give you a cup to urinate in which can then be evaluated in the lab.  With some conditions, your doctor may want to obtain a urine sample by inserting a catheter through your urethra into your bladder, but this is fairly uncommon.

Is It Really Blood?

You should know that there are instances where it may look like blood is in your urine, but really isn't. For women, an example would be vaginal bleeding that flows from the vagina during urination, giving the false appearance of blood in the urine.

Foods like beets and rhubarb and can alter the color of urine, but most people have to eat a lot of these foods to give their urine the appearance of containing blood. Medications can also cause the color of urine to change.

What Does Blood in the Urine Look Like?

Blood can appear in the urine as a pink, brown, or red hue, and may also contain clots.

Gross hematuria - When you can physically see blood in your urine, it is called gross hematuria. 

Microscopic hematuria - Frequently, blood in the urine is not visible to the naked eye and is only seen under the microscope.  Scientists describe the presence of microscopic hematuria as a urine sample that contains more than 5 red blood cells per high power field.


The causes of gross and microscopic hematuria can be similar, but there are also important differences.  While microscopic hematuria may arise from anywhere in the urinary tract, beginning with the kidneys and ending with the urethra (the passage from the bladder to the outside of the body), gross hematuria is usually due to problems in the lower, collecting system portion of the urinary tract.

Single vs Multiple Episodes of Hematuria

Hematuria is a very common symptom, occurring in roughly a third of people at some time in their life.  A single episode of hematuria - especially microscopic hematuria - may be related to mild conditions such as trauma, whereas persistent or recurrent hematuria is more likely to suggest a significant medical problem is going on.

Diagnosing Blood in Urine

If your doctor finds blood in your urine, she will first take a careful history and perform a physical exam. 

A full urinalysis will be done to look not only for red blood cells, but protein, glucose, signs of infection, and more.  The presence of protein (proteinuria) in particular may help to narrow down the possible causes of hematuria.

Blood tests to evaluate kidney function (creatinine (CR) and blood urea nitrogen (BUN)), as well as other tests may be ordered.

Imaging tests may include an intravenous pyelogram, ultrasound, CT or MRI are often done next if a specific cause has not been determined.

A cystoscopy is a test in which a narrow flexible catheter attached to a camera is inserted through the urethra into the bladder, to look for signs of inflammation or tumors. 

A biopsy may also be done to evaluate any suspicious findings in your kidneys or bladder.

Blood in Urine and Cancer

Certainly, cancer is not the most likely cause of blood in urine, but it is an important cause to evaluate if other causes are not found.  We will start with these causes of hematuria since they can be the most serious.

Bladder Cancer and Hematuria

While bladder cancer certainly isn't the most common cause of blood in the urine, blood in the urine can be the most common symptom of bladder cancer.  Sometimes people also develop symptoms such as frequent urination and painful urination, but it's common for this cancer to present with painless hematuria.  Blood in urine which is painless, especially in a man over the age of 50 who has smoked, needs to be evaluated carefully, usually with cystoscopy, to check for this possibility.

Bladder cancer is most treatable in the early stages of the disease, so following up on this symptom is very important.  Currently, around half of people are diagnosed with bladder cancer when it is still in these early stages.  Risk factors for bladder cancer may include a history of smoking (felt to be responsible for half of these cancers) as well as occupations such as being a hairdresser or printer.

Kidney Cancer and Hematuria

Blood in urine can also be a sign of kidney cancer.  Risk factors for kidney cancer (also called renal cell carcinoma) include those found with bladder cancer, but it also tends to run in families and there are genetic syndromes which raise the risk.

Prostate Cancer and Hematuria

Prostate cancer is not a common cause of blood in urine but is important to look for if there are otherwise not reasons to explain this symptom.

Non-Cancerous Causes of Blood in Urine

Other than cancer, there are many other reasons why blood may be present in your urine.  This includes:

  • Bladder infections (urinary tract infections) - Urinary tract infections are very common and can cause both gross and microscopic hematuria.  While pain is common, these can be painless, especially in elderly people and children.
  • Kidney stones - Kidney stones can cause blood in the urine.  As these stones travel down the ureters (tube between the kidneys and the bladder) and the bladder they can cause pain which may begin as a dull ache and can progress to severe pain which has been likened to that of childbirth.
  • Exercise-induced hematuria (march hematuria) - Vigorous exercise is a fairly common cause of microscopic hematuria, and its presence in military recruits earned it the name "march hematuria."
  • Interstitial cystitis - Interstitial cystitis is a condition which often produces significant pain with urination as well.
  • Trauma
  • Sexually transmitted diseases
  • Polycystic kidneys
  • High blood pressure
  • Medications
  • Diabetes
  • Tuberculosis
  • Prostatitis
  • Kidney glomerular disease
  • Bleeding disorders such as hemophilia, or blood thinners such as aspirin, Plavix, or coumadin.

Do Not Ignore Blood in Your Urine

If you think that you have blood in your urine, you need to report it to your doctor, even if you are not sure. A simple urinalysis can confirm the presence of blood in your urine. If you have other symptoms that accompany blood in your urine, like a fever and pain on your side, then you should seek emergency care.

Secondly, you should avoid treating hematuria with home remedies or herbal supplements. Remember that blood in the urine is a symptom of a disease or other condition. To resolve hematuria, you need to treat the cause, not just symptoms. It really is best to see a doctor and allow them to evaluate why you are having blood in your urine.


American Society of Clinical Oncology. Bladder Cancer: Symptoms and Signs. 06/2015.

Nielsen, M., and A. Qaseem. Hematuria as a Marker of Occult Urinary Tract Cancer: Advice for High-Value Care From the American College of Physicians. Annals of Internal Medicine. Published online 26 January 2016.

Mercieri, A. Exercise-induced hematuria. UpToDate. Updated 10/14/15.

Niemi, M., and R. Cohen. Evaluation of microscopic hematuria: a critical review and proposed algorithm. Advances in Chronic Kidney Disease. 2015. 22(4):289-96.

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