Hematuria is the presence of blood, specifically red blood cells, in the urine. Whether the blood is visible only under a microscope or visible to the naked eye, hematuria is a sign that something is causing bleeding in the genitourinary tract: the kidneys, the ureters (tubes that carry urine from the kidneys to the bladder), the prostate gland (in men), the bladder, or the urethra (tube that carries urine from the bladder out of the body).

Bleeding may happen once or it may be recurrent. It can indicate different problems in men and women. Causes of this condition range from non–life threatening (e.g., urinary tract infection) to profoundly serious (e.g., cancer, kidney disease). Therefore, a physician should be consulted as soon as possible.

Types

There are two types of hematuria, microscopic and gross (or macroscopic). In microscopic hematuria, the amount of blood in the urine is so small that it can be seen only under a microscope. A small number of people experience microscopic hematuria that has no discernible cause (idiopathic hematuria). These people normally excrete a higher number of red blood cells.

In gross hematuria the urine is pink, red, or dark brown and may contain small blood clots. The amount of blood in the urine does not necessarily indicate the seriousness of the underlying problem. As little as 1 milliliter (0.03 ounces) of blood will turn the urine red.

"Joggers hematuria" results from repeated jarring of the bladder during jogging or long-distance running.

Hematuria that is not blood related is called pseudohematuria. Excessive consumption of beets, berries, or rhubarb; food coloring; and certain laxatives and pain medications can produce pink or reddish urine.

Incidence

Hematuria occurs in up to 10% of the general population.

Causes

Many conditions are associated with hematuria. The most common causes include the following:

• Benign prostate hypertrophy (BPH) in men over 40
• Kidney and bladder stones
• Kidney disease
• Medications (e.g., quinine, rifampin, phenytoin)
• Trauma (e.g., a blow to the kidneys)
• Tumors and/or cancer in the urinary system
• Urinary tract blockages
• Viral infections of the urinary tract and sexually transmitted diseases, particularly in women

There are rare diseases and genetic disorders that also cause hematuria. Some of these are:

• Sickle cell anemia (inherited blood disorder found in African Americans)
• Systemic lupus erythmatosus (chronic inflammatory disorder of connective tissue)
• von Hippel-Landau disease (hereditary disease in which benign tumors form on the spinal cord, kidneys, testicles, and other organs)

Signs and Symptoms

In many cases, blood in the urine (gross or microscopic) is the only sign of a disorder. In others, a variety of symptoms, such as the following, may be present.

• Abdominal pain
• Decreased urinary force, hesitance, incomplete voiding
• Fever
• Frequent urination (polyuria)
• Pain during urination (dysuria)
• Pain in the flank or side
• Urinary urgency