High leukocyte levels in the urine may mean a urinary tract infection or other underlying inflammatory medical problems, such as kidney infection and kidney stones.

Leukocytes, also known as white blood cells, are a central part of the immune system. They help to protect the body against foreign substances, microbes, and diseases.

It is uncommon to have high levels of leukocytes passing into the urine. However, high leukocyte levels in the urine may indicate an underlying infection or disruption to the urinary system.

This article will look at common causes of leukocytes in the urine.

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Leukocytes can occur in urine for various reasons.

Urinary tract infections

A urinary tract infection (UTI) is a common cause of leukocytes in the urine. These infections can affect any part of the urinary system, including the bladder, urethra, and kidneys. The lower urinary tract—especially the bladder and urethra—are common sites.

A UTI usually happens when bacteria enter the urinary tract through the urethra. They then multiply in the bladder.

If a UTI occurs in the bladder and the person does not seek treatment, the infection can spread to other sites, including the urinary tract and kidneys.

Learn more about the differences between bladder infections and UTIs here.

Kidney infection

The number of white blood cells in the urine can increase if there is a kidney infection.

Kidney infections often start in the lower urinary tract but spread to the kidneys. Occasionally, bacteria from other body parts reach the kidneys through the bloodstream.

Risk factors for kidney infections include

Learn about the differences between kidney infections and UTIs here.

Kidney stones

A high number of leukocytes can indicate a person has kidney stones.

Kidney stones can travel to the urinary tract and can disrupt the flow of urine. Blockages here can cause an increase in leukocyte production and leukocytes passing into the urine.

Other blockages to the urinary tract can also increase the risk of infection and the presence of leukocytes.

Discover 10 ways to prevent kidney stones here.

Holding in urine

Holding in urine can cause the bladder to weaken, making it difficult to empty. Doctors refer to this as urinary retention.

Urine accumulation increases the risk of bacterial infection in the bladder. This can raise the levels of leukocytes in the urine.

Learn more about the side effects of holding in urine here.

The following can also cause raised levels of leukocytes in the urine:

Leukocytes in the urine cause different symptoms depending on the cause.

Urinary tract infections typically cause cloudy or foul-smelling urine. Other signs include frequent urination, pain or burning sensation when passing urine, or blood in the urine.

Other symptoms of infection or dysfunction in the urinary tract include:

If a person presents with symptoms of a UTI or other urinary tract dysfunction, doctors will perform tests to diagnose the underlying cause.


Doctors will first order a urine analysis (urinalysis) to screen the urine for abnormalities which may be enough to detect any problems.

People who suspect leukocytes in the urine provide a urine sample that their doctor can analyze in three ways: Visual exam, dipstick test, and microscopic exam.

  • Visual exam: Technicians examine the appearance of the urine. Cloudiness or an unusual odor may signal an infection or another potential problem. The food that a person eats can also affect urine color.
  • Dipstick test: A thin, plastic stick with strips of chemicals is placed in the urine to detect abnormalities. The chemicals on the strip will change color to indicate if certain substances are present.
  • Microscopic exam: Professionals examine urine drops under a microscope. The presence of leukocytes might be a sign of infection.

Other tests

If blood or other substances are present in the urine, the physician may perform more tests to identify the cause of the problem.

The problem may be any of the above conditions or a more serious noninfectious illness, such as a blood disorder, autoimmune disease, or cancer. The doctor will order additional tests as needed.

Learn more about the different causes of blood in urine in males and females here.

Sterile pyuria

It is possible to have white blood cells in the urine without a bacterial infection. Sterile pyuria is the persistent presence of white blood cells in the urine without a bacterial cause.

A correct diagnosis is vital for identifying a path of treatment.

Treatment for leukocytes in the urine depends on the cause and if there is an infection. Antibiotic therapy will clear up the infection for some conditions, such as a bacterial UTI, relatively quickly.

Patients may require more in-depth treatment for severe infections, and in some cases, hospitalization may be necessary.

Lifestyle changes can help reduce the symptoms of some conditions that cause leukocytes to enter the urine.

These include:

  • drinking more water
  • urinating when you have to go
  • staying as healthy as you can

Taking acetaminophen, ibuprofen, or prescription drugs may also help to ease pain in the urinary system.

High levels of leukocytes in the urine typically indicate an infection in the urinary system. Leukocytes are white blood cells that the body produces to combat infection.

Symptoms of urinary tract infections include cloudy or foul-smelling urine, pain, cramps, and nausea.