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 tubes that carry urine from the kidneys to the bladder (ureters), the prostate gland (in men), the bladder, or the tube that carries urine from the bladder out of the body (urethra).

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 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.

Reddish urine that is not caused by blood in the urine 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.