Definition

Blood in the urine is also called hematuria. Normally, urine does not contain blood.

There are two kinds of hematuria:

• Microscopic hematuria—Urine contains a very small amount of blood, which is not visible to the naked eye.
• Gross hematuria—Urine is visibly discolored by blood, appearing red or tea-colored.

Causes

In some cases, the cause of hematuria is never found. The list of known causes is lengthy. Some more common causes include:

• Injury to the abdomen, pelvis, or internal organs of the urinary tract
• Vigorous exercise (resolves with rest)
• Urinary tract infection or kidney infections
• Cancer of the prostate, kidney, or bladder
• Kidney disease
• Kidney stones
• Bleeding disorders (eg, hemophilia)
• Certain congenital diseases (eg, polycystic kidneys)
• Radiation of the pelvis (for cancer treatment)
• Certain medications

Risk Factors

Risk factors include:

• Smoking
• Medicines (eg, certain antibiotics and pain medicines)
• Recent upper respiratory tract infection
• Family history of kidney problems

Kidney Stones Can Cause Microscopic Hematuria

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Symptoms

In some cases, there may not be additional symptoms.

But, if you have an underlying condition, you may have other symptoms. For example, kidney stones can cause blood in the urine, along with pain in the side, abdomen, or groin.

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. You may be referred to a doctor who specializes in kidney disease (nephrologist) or the urinary system (urologist).

Your doctor may need to test your bodily fluids. This can be done with:

• Urine tests—tests to confirm the presence of blood and look for protein, bacteria, or cancer cells in the urine
• Blood tests—tests to check how well the kidneys are functioning and to look for medical conditions that cause hematuria

Your doctor may need to view your bodily structures. This can be done with:

• X-ray
• Ultrasound
• CT scan
• MRI scan
• Cystoscopy

Treatment

Treatment will depend on the cause of hematuria. Some causes of hematuria require no treatment (eg, exercise-induced) or will resolve on their own (eg, passage of a kidney stone). Other causes will respond to medicine. For example, treating a urinary tract infection with antibiotics will stop the hematuria. Still other causes may require surgery, such as the removal of a bladder or treatment for prostate cancer.

Prevention

Treating the underlying condition that causes hematuria may help prevent it from occurring.