A Sign of a Urinary Tract Infection: Leukocytes in Urine

Urine samples can sometimes reveal leukocytes. These are a type of cell not normally found in the urine in great numbers.

Having leukocytes in the urine may signal an infection. A test for this may be done routinely for some people, such as pregnant women.

What are leukocytes?

Leukocyte is the technical name for a white blood cell, often seen shortened to WBC. They are central to immune responses that protect people from infection.

These white blood cells come in a number of forms, including phagocytes and lymphocytes.

Phagocytes are produced in the bone marrow. Their job is to engulf foreign particles like bacteria. This means surrounding a particle, internalizing it, and destroying it.

Lymphocytes are the white blood cells that recognize foreign particles based on previous encounters. They are the cells that make up the "adaptive" immunity. This is the complex ability of the immune system to remember an infection and launch more specific responses to it.

Lymphocytes also produce antibodies, which bind to foreign particles so that they may be recognized for destruction.

There are other types of leukocyte. Cytotoxic white blood cells, for example, have the ability to kill other cells.

What do high leukocytes in urine mean?

Having a high number of leukocytes in the urine indicates inflammation in the bladder or kidney.

Having some leukocytes in the urine does not always mean infection, though. The level must be high. The urine sample also needs to be given carefully, because contamination can come from the genitals, for example.

Leukocytes and nitrites

When doctors use a dipstick test for urine infection, these detect certain chemicals in the urine.

Chemical test strips can pick up substances known as leukocyte esterase and nitrite in the urine. Both of which are potential indicators of infection.

The presence of nitrite in the urine is highly specific of a bacterial infection. This does not pick up all bacteria, though.

If there is no leukocyte esterase in the urine, this means an infection is unlikely.

What is leukocytes in the urine without nitrite?

If the test for leukocyte esterase is positive but the nitrite one is negative, this can still mean there is an infection.

The reason for this is a limitation of the nitrite test. It is very specific, which means it can pick up a bacterial infection with certainty. However, it is not very sensitive, which means that not all bacterial infections can be picked up.

Having leukocytes in the urine without nitrite can also mean a false-positive result. This is a result suggesting a bacterial infection when there is none. In this case, further lab tests can be done.

Having leukocytes in the urine does not always mean there is an infection. If there are leukocytes but no nitrite, it could be a negative result.

This is particularly true for cases in which there is another reason for the presence of inflammation in the urinary tract, or for women who may have leukocytes introduced into the urine from their genital canal when giving a sample.

Women need to clean the area around the urethral opening before giving the sample, using clean water and holding their labia aside. Men should hold back their foreskin.

Samples need to be taken halfway through urinating. The initial amount of urine that comes out may be contaminated and so should not be captured.

Diagnosis and treatment of urinary tract infections

Doctors tend to shorten urinary tract infection to UTI. A UTI can affect the upper or lower tract. Upper UTIs can involve the kidneys.

Lower urinary tract infections may also have these specific names:

Cystitis, meaning bladder infection

Urethritis, meaning infection of the urethra, which is the tube carrying urine away from the bladder

Prostatitis, involving the prostate

This article is most concerned with bacterial lower UTIs because they are a common cause of leukocytes in the urine.

After doctors check for symptoms, diagnosis of lower UTIs is made using a urine dipstick or urinalysis test. A urine culture may also be used.

Symptoms vary, and often overlap, but might include:

Urinating more often, and a sensation of needing to urinate

Burning or painful passing of only small amounts of urine

Difficulty urinating or pain when passing

Discharge or cloudy urine

More general symptoms can include fever and chills, flank or lower abdominal pain, nausea, and vomiting. It is important to get medical care if such symptoms occur with a urinary infection

Most simple urinary tract infections that cause symptoms can be treated with antibiotics prescribed by a doctor. A number of different antibiotics may be used, although the doctor will avoid some in pregnant women.

More serious infections with complications such as abscesses may need more intensive treatment such as surgery or catheter drainage.

Infections that do not produce symptoms will be left without treatment unless there is a higher risk. High risk includes having a suppressed immune system.

Antibiotic drugs may be changed to match the specific bacteria causing the infection if tests are done that identify the bacteria involved

Prevention of urinary infections in women

Some women have urinary tract infections often. Some preventive measures may prevent these, including:

Drinking more fluid

Emptying the bladder without delay

Urinating straight after sex

Taking measures around sex, such as avoiding spermicides

Hygiene, including wiping front to back after pooping

Using unperfumed, mild soaps for cleansing the genital area

Wearing breathable, natural fabrics such as 100 percent cotton

Source: MNT