Blood in the urine (hematuria) can make urine appear pink, red, or brown, depending on the amount of blood, how long it has been in the urine, and how acidic the urine is. An amount of blood too small to change color of the urine (microscopic hematuria) may be found by chemical tests or microscopic examination. Microscopic hematuria may be found when a urine test is done for another reason.
People with hematuria may have other symptoms of urinary tract disorders Overview of Urinary Tract Symptoms Kidney and urinary tract disorders can involve one or both kidneys, one or both ureters, the bladder, or the urethra, and in men, the prostate, one or both testes, or the epididymis. Problems... read more , such as pain in the side or back (flank), lower abdominal pain, an urgent need to urinate, or difficulty urinating, depending on the cause of blood in the urine. If sufficient blood is present in the urine, the blood may form a clot. The clot can completely block the flow of urine, causing sudden extreme pain and inability to urinate. Bleeding severe enough to cause such a clot is usually caused by an injury to the urinary tract.
Red urine is not always caused by red blood cells. Red or reddish brown discoloration may also result from the following:
Hemoglobin (which carries oxygen in red blood cells) in the urine due to the breakdown of red blood cells
Muscle protein (myoglobin) in urine due to the breakdown of muscle cells
Porphyria (a disorder caused by deficiencies of enzymes involved in the production of heme, a chemical compound that contains iron and gives blood its red color)
Foods (for example, beets, rhubarb, and sometimes food coloring)
Drugs (most commonly phenazopyridine, but sometimes cascara, diphenylhydantoin, methyldopa, rifampin, phenacetin, phenothiazines, and senna)
Blood in the urine may be caused by problems anywhere along the urinary tract from the kidneys to the ureters, bladder, or urethra. Some women at first mistake vaginal bleeding Vaginal Bleeding Abnormal vaginal bleeding includes any vaginal bleeding that occurs Before puberty During pregnancy After menopause Between menstrual periods read more for blood in the urine.
The most common causes differ somewhat by the person's age but overall are
Less common causes include
Cancer (of the kidneys Kidney Cancer Kidney cancer may cause blood in the urine, pain in the side, or fever. Cancer is most often detected by accident when an imaging test is done for another reason. Diagnosis is by computed tomography... read more , bladder Bladder Cancer Bladder cancer most often causes blood in the urine. To make the diagnosis, a thin, flexible viewing tube (cystoscope) is inserted through the urethra into the bladder. Many cancers are treated... read more , or prostate Prostate Cancer The risk of prostate cancer increases as men age. Symptoms, such as difficulty urinating, a need to urinate frequently and urgently, and blood in the urine, usually occur only after the cancer... read more )
Noncancerous enlargement of the prostate (benign prostatic hyperplasia Benign Prostatic Hyperplasia (BPH) Benign prostatic hyperplasia (BPH) is a noncancerous (benign) enlargement of the prostate gland that can make urination difficult. The prostate gland enlarges as men age. Men may have difficulty... read more )
Disorders of the small blood vessels of the kidneys (called kidney filtering disorders Overview of Kidney Filtering Disorders Each kidney contains about 1 million filtering units (glomeruli). The glomeruli are made up of many microscopic clusters of tiny blood vessels (capillaries) with small pores. These blood vessels... read more or glomerular disorders)
Narrowing scars (called strictures Urethral Stricture A urethral stricture is scarring that narrows the urethra. A urethral stricture may be Present from birth Develop after an infection or injury A urethral stricture most commonly results from... read more ) or other abnormalities of the ureters
Cancer and benign prostatic hyperplasia may cause blood in the urine. These disorders are a concern mainly in people over 50, although younger people with risk factors (smoking, family history, or chemical exposures) may develop cancer.
Disorders of the microscopic blood vessels of the kidneys (glomeruli) can be a cause at any age.
Kidney filtering disorders (glomerular disorders Kidney Filtering Disorders read more ) may be part of a kidney disorder or may occur as a result of a disorder elsewhere in the body. These disorders are more likely if the urine has protein, clumps of red blood cells (called red blood cell casts), or malformed red blood cells. Such disorders include infections (such as a heart valve infection), connective tissue disorders (such as systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more ) and vasculitis Overview of Vasculitis Vasculitic disorders are caused by inflammation of the blood vessels (vasculitis). Vasculitis can be triggered by certain infections or drugs or can occur for unknown reasons. People may have... read more , blood disorders (such as serum sickness), or certain chronic disorders (such as diabetes Diabetes Mellitus (DM) Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more ). Also, almost any kind of kidney damage may cause small amounts of blood in the urine.
Severe injuries, such as from a fall or a motor vehicle crash, can injure the kidneys or bladder and cause bleeding.
Schistosoma haematobium, a parasitic worm that causes disease in Africa and, to a lesser extent, in India and parts of the Middle East, can invade the urinary tract, causing blood in the urine. Doctors consider schistosomiasis Schistosomiasis Schistosomiasis is infection caused by certain flatworms (flukes), called schistosomes. People acquire schistosomiasis by swimming or bathing in fresh water that is contaminated with the flukes... read more only if people have spent time in areas where the worm is found. Tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs. Tuberculosis is spread mainly when people breathe air... read more may cause blood in the urine.
Doctors first try to establish that bleeding is the cause of red urine. Then they look for the cause of the bleeding, including where in the urinary tract (or occasionally elsewhere) the bleeding is originating. The following information can help people know when to see a doctor and what to expect during the evaluation.
In people with blood in the urine, certain symptoms and characteristics are cause for concern. They include
Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What they find during the history and physical examination often suggests a cause of the blood in the urine and the tests that may need to be done (see table Some Causes and Features of Blood in the Urine Some Causes and Features of Blood in the Urine Blood in the urine (hematuria) can make urine appear pink, red, or brown, depending on the amount of blood, how long it has been in the urine, and how acidic the urine is. An amount of blood... read more ).
Doctors ask how long blood has been present and whether there have been any previous bleeding episodes. They ask about fever, weight loss, or symptoms of urinary blockage, such as difficulty starting urination or inability to completely empty the bladder. Pain or discomfort is an important finding. Burning during urination or dull pain in the lower abdomen just above the pubic bone suggests a bladder infection. In men, mild to moderate pain in the lower back or pelvis is often the result of a prostate infection Prostatitis Prostatitis is pain and swelling, inflammation, or both of the prostate gland. The cause is sometimes a bacterial infection. Pain can occur in the area between the scrotum and anus or in the... read more . Extremely severe pain is usually due to a stone or a blood clot blocking the flow of urine.
Doctors then do a physical examination. Usually, a pelvic examination is necessary in women. If women have blood in the vagina, a catheter may need to be inserted into the bladder to see whether the source of blood is the bladder or the vagina. In men, doctors usually do a digital rectal examination to check the prostate.
Sometimes doctors can make a diagnosis based on the person's symptoms and the results of the physical examination. More often, because symptoms of many disorders overlap, testing is needed to determine the cause (or sometimes the presence) of blood in the urine. Urinalysis Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more is the first test done. Urinalysis can detect blood (confirming that the red color of the urine is caused by blood) and may show evidence of a kidney filtering disorder. If infection is suspected, urine culture is usually done.
In all people over 50 and in people who have risk factors for cancer, doctors typically use a flexible viewing tube to look inside the bladder (cystoscopy Cystoscopy A doctor can diagnose some disorders of the bladder and urethra (for example, bladder tumors, stones in the bladder, benign prostatic enlargement) by looking through a flexible viewing tube... read more ) to determine the cause of bleeding.
People of any age who do not have an infection or a kidney filtering disorder as the cause of visibly bloody urine typically have imaging studies, such as computed tomography (CT), ultrasonography, or magnetic resonance imaging (MRI) of the abdomen and pelvis. For people under 50 who have only microscopic hematuria and no other abnormalities detected during the physical examination, blood tests, or urinalysis, doctors may simply repeat the urinalysis in 6 or 12 months. If blood is still present, they will do further tests.
If doctors suspect a kidney filtering disorder (based of the results of urinalysis), they usually do blood tests to evaluate kidney function and sometimes a kidney biopsy Kidney biopsy Site-specific biopsies and cell sampling are also used in the evaluation of people with suspected kidney and urinary tract disorders. (See also Overview of the Urinary Tract.) A kidney biopsy... read more . Blood tests for sickle cell disease Sickle Cell Disease Sickle cell disease is an inherited genetic abnormality of hemoglobin (the oxygen-carrying protein found in red blood cells) characterized by sickle (crescent)-shaped red blood cells and chronic... read more may be needed in people of African or Mediterranean descent who are not known to have the disease.
In men who are 50 or older, doctors usually measure the level of prostate-specific antigen (PSA) Diagnosis The risk of prostate cancer increases as men age. Symptoms, such as difficulty urinating, a need to urinate frequently and urgently, and blood in the urine, usually occur only after the cancer... read more in the blood.