Possible Causes of Blood in Urine (Hematuria)

Finding blood in your urine can be frightening, but you should know that there are many different causes of hematuria (blood in urine), some of which are relatively benign and easily treated. Others may be indicative of a serious medical condition warranting further investigation.

Beets sitting on a wooden table

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As such, you should never discount blood in urine as being "minor," particularly if it is persistent and accompanied by other symptoms.

Having hematuria does not always mean you have an underlying abnormality. It may simply be the result of a minor injury to the urethra (the tube through with urine leaves the body) or a side effect of a drug that needs to be changed.

Here are 10 of the most common causes worth considering:

Vaginal Bleeding

In women, the most common cause of blood in urine is vaginal bleeding, including normal menstrual bleeding. This is rarely a cause for alarm and will eventually normalize without treatment.

Although many women are accustomed to seeing a little blood in urine during her period, hematuria that occurs outside of menses should raise a red flag.

If vaginal bleeding is the cause of hematuria, the doctor will perform tests to determine the underlying cause.


Certain drugs, including blood thinners such as warfarin, can lead to blood in the urine. Doctors often prescribe blood thinners if you have a heart or blood vessel disease, or if you have poor blood flow to your brain.

Blood thinners reduce the risk of heart attack and stroke by reducing the formation of blood clots in your arteries and veins. You may also take a blood thinner if you have an abnormal heart rhythm, have undergone heart valve surgery, or have congenital heart defects.

Certain Foods

Some foods, such as beets, can cause discoloration of your urine. This red color is the result of unmetabolized pigments in your food that is passed from the kidneys into your urine.

As such, the redness in urine is not hematuria but simply a benign discoloration that will eventually normalize.

Low Platelets

Platelets are the small cells in your body that stick to the wall of a blood vessel following injury. They clump together and prevent bleeding. If you have low platelets in your blood, your ability to form clots and stop bleeding may be impaired. This is called thrombocytopenia.

The causes of thrombocytopenia are many and include aplastic anemia, alcohol abuse, viral infections (like chickenpox and Epstein-Barr), liver cirrhosis, leukemia, and iron, folate, or vitamin B-12 deficiency.

Urinary Stones

Kidney stones and bladder stones are small, hard deposits that develop when minerals in your urine start to crystallize. As they are passed from the body in urine, they can cause extreme pain and bleeding.

The urine may be pink or reddish, or the blood may only be visible only with a urine dipstick testing or microscopic examination of the urine.

Recent Urinary Tract Procedures

There are a number of procedures that exist to check the functioning of the kidneys, the bladder, and your urethra, or to eradicate other health conditions.

These include cystoscopy, pyelograms, and voiding cystourethrogram. One side effect of these procedures can be blood in the urine.

Urinary Tract Infections

A urinary tract infection (UTI) is a bacterial infection that occurs when bacteria invade the urinary tract system and then multiply.

UTIs are more common in women and principally affect the bladder and urethra. Bladder infections (cystitis) are usually caused by Escherichia coli (E. coli), a type of bacteria commonly found in the gastrointestinal tract.

Urinary Tract Injury

The kidneys and the rest of the urinary tract can become injured due to blunt force (such as a motor vehicle crash, a fall, or a sports injury), a penetrating force (such as gunshot or stab wounds), or surgery.

Injuries to the urinary tract often occur together with injuries to other organs, especially the abdominal organs.

Renal Blood Clots

Also known as renal vein thrombosis (RVT), this is a blockage of the renal vein, which carries blood away from the kidney via a blood clot. RVT is not common and can cause severe damage to the kidneys and other life-threatening injuries.

Bleeding Disorders

Hemophilia is a disorder in which your blood fails to clot normally. If an injury or infection occurs somewhere in the urinary tract, it may cause bleeding that people without hemophilia may be able to control.

By contrast, the same infection or injury may result in sustained bleeding and the development of hematuria.

Polycystic Kidney Disease

Polycystic kidney disease (PKD) is an inherited disorder that causes many fluid-filled sacs, called cysts, to form in both kidneys. In addition to blood in urine, symptoms of PKD include high blood pressure, back or side pain, and a swollen abdomen.

Should you notice blood in your urine that is not caused by menstrual bleeding, see your doctor as soon as possible for evaluation and diagnosis.

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  2. Mladenov BS, Mariyanovski V, Hadzhiyska V. Macroscopic hematuria in patients on anticoagulation therapy. Cent European J Urol. 2015;68(3):330-3. doi:10.5173/ceju.2015.658

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Additional Reading
  • Medline Plus. Urine - Bloody.