Leukocytes are white blood cells that are vital to immune system defenses. Leukocytes in the urine can indicate an infection or inflammation in the urinary tract.

Having leukocytes in the urine may be a sign of infection. A urinary tract infection (UTI) is often responsible for increasing leukocyte levels in the urine.

UTIs are one of the most common infections worldwide, with an estimated 404 million cases estimated to have occurred in 2019.

This article will explain what an excess of white blood cells in the urine means, as well as how to treat a UTI.

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Leukocytes are white blood cells. They are heavily involved in immune responses that protect people from infection.

There are several types of white blood cells. The two main leukocytes are phagocytes and lymphocytes.

Phagocytes are produced in the bone marrow. Their job is to engulf foreign particles, such as bacteria or parasites. This means surrounding, absorbing, and destroying a particle.

Lymphocytes are the white blood cells that recognize foreign particles based on previous encounters. They contribute to “adaptive” immunity, the sophisticated ability of the immune system to remember and produce tailored and effective responses to an infection.

Lymphocytes produce antibodies. These bind to foreign particles and allow the immune system to remember them later on, should the same infection occur.

An unusually high number of leukocytes in the urine indicates inflammation or infection along the urinary tract.

These will show in a urine test. The doctor may carry out a dipstick test, in which a chemical strip detects an enzyme called leukocyte esterase that points to the presence of white blood cells, typically related to an infection. The dipstick test also highlights nitrites, which are a waste product from the breakdown of certain bacteria.

The presence of nitrites in the urine is highly specific to certain bacterial infections. Nitrites do not occur with all types of bacteria.

An absence of leukocyte esterase in the urine means that the urine is not likely to contain white blood cells, so it is not likely to be carrying infectious agents.

The doctor or laboratory technician may also perform a urine culture. This involves growing bacteria from the urine to identify the cause of the infection.

During pregnancy, women receive testing for urinary infections during their first prenatal visit, and they might need testing at other times during their pregnancy.

Indeed, UTIs are common during pregnancy and doctors will often find leukocytes in the urine that suggest the presence of an infection. However, some women who are pregnant have a bacterial infection in the urine without symptoms.

This is known as asymptomatic bacteriuria.

Normal results

Normal urine pH is slightly acidic, with usual values of 5.5 to 7.5. However, the normal range falls between 4.5 to 8.0.

A urine pH of 8.5 to 9.0 indicates the presence of bacteria, such as Proteus, Klebsiella, or Ureaplasma urealyticum, which cause UTIs.

Leukocytes in the urine without nitrite

If the test for leukocyte esterase is positive but finds no nitrite, an infection may still be present.

The test is particular to certain bacterial enzymes, which means it can pick up specific bacterial infections with more certainty. However, it is not highly sensitive, which means that the test does not pick up all bacterial infections. E. coli bacteria are most commonly associated with nitrites in the urine.

Having leukocytes in the urine without nitrites can also lead to a false-positive result that points to a bacterial infection when there is none. The pathologist or technician will carry out further testing to confirm the presence of an infection.

This is particularly true when there are other causes of inflammation in the urinary tract. The genital canal can sometimes pass leukocytes into the urine during the process of giving a sample.

To avoid a false-positive result, people should clean the area around the urethral opening before giving the sample, using cleansing wipes and holding their labia or foreskin aside.

Take a sample halfway through urinating. The initial stream of urine may be contaminated by skin bacteria, so taking a sample this way also reduces the risk of a misleading outcome.

A UTI can affect the upper and lower urinary tracts, kidneys, bladder, urethra, and prostate.

Lower urinary tract infections may also have these specific names:

Both upper and lower UTIs can lead to leukocytes in the urine.

Symptoms vary and often overlap, but they might include:

Symptoms of more serious infections can include:

It is important to seek medical attention right away if any of these symptoms occur.

Kidney stones

Kidney stones are crystals that form when calcium and other minerals build up in a person’s urine. They can vary from small to large. If it’s the latter, they may cause pain and get stuck along the way, causing the flow of urine to be blocked.

Signs of kidney stones include:

Inflammation in the body can trigger the release of leukocytes. This can come from an injury, infection, or disease.

Leukocytes in the urine can also be from sexually transmitted infections, fungal infections, genitourinary tuberculosis, certain autoimmune or inflammatory diseases, and even inflammation outside of the urinary tract.

Most UTIs cause manageable infections that an individual can treat with antibiotics. The doctor may prescribe a range of different antibiotics, although they will only prescribe certain antibiotics to women during pregnancy.

More severe or serious infections with complications, such as abscesses, kidney involvement, or any infections that occur during pregnancy, may need more intensive treatment, including hospitalization.

The doctor may need to change the course of antibiotic drugs once the bacteria are identified. Certain bacteria can only be treated with specific antibiotics.

Below are some commonly asked questions about leukocyte esterase in urine.

Should I worry about leukocytes in urine?

Leukocytes in the urine are often the result of inflammation or infection, such as a UTI.

A person should not be concerned about this, as most UTIs can be treated with antibiotics. If leukocytes in urine point to a more serious infection or complication, more intensive treatment may be needed.

Can you have leukocyte esterase in urine but no UTI?

Leukocyte esterase in the urine does not always mean a person has a UTI. It can also point to kidney stones or general inflammation from an injury, infection, or disease.

Can anxiety cause leukocytes in urine?

According to a 2017 study, there may be a reciprocal relationship between anxiety/depression and lower urinary tract symptoms. However, more research is needed on this topic.

Leukocytes in the urine can indicate an infection or inflammation in the urinary tract.

It can also point to kidney stones or general inflammation as a result of injury.

Treatment options for UTIs include antibiotics but, in more severe cases, may require intensive interventions.

Infections that are more severe or carry complications, such as abscesses, kidney involvement, or those occurring during pregnancy, might require more intensive treatment, potentially involving hospitalization.