Leukocyte Esterase in Urine (Urine Leukocytes): What Your Result Means

What a positive leukocyte esterase dipstick means, how trace to 3+ results are reported, when a result can be false, and how it differs from a microscopic white cell count.

Published

August 10, 2024

Last updated

September 30, 2026

Read time

9 min read

Medically reviewed by

Rhonda Collins, FNP-C

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A positive leukocyte esterase result means the urine dipstick found an enzyme made by white blood cells, so white blood cells are probably present in your urine. The most common reason is inflammation in the urinary tract, often from a urinary tract infection (UTI). A positive result does not diagnose a UTI by itself: vaginal secretions and some other infections can also turn the test positive, and a follow-up microscopic exam or urine culture is what confirms the cause. UCSF explains the leukocyte esterase urine test, and the Merck Manual describes it as a sign of inflammation.

What is leukocyte esterase in urine?

Leukocyte esterase is an enzyme released by neutrophils, a type of white blood cell (leukocyte). A urinalysis dipstick has a color-sensitive pad that reacts with this enzyme, so the test is an indirect way to check for white blood cells in urine, a finding called pyuria. AAFP’s urinalysis review covers the chemistry. On a lab report it may appear as “leukocyte esterase,” “LE,” “urine leukocytes,” or “WBC esterase.” UCSF lists the alternative names.

What do negative, trace, and 1+ to 3+ results mean?

Leukocyte esterase is reported as negative, trace, or a positive grade, depending on how strongly the dipstick pad changes color. Positive grades are written as 1+, 2+, and 3+ on some reports and as small, moderate, and large on others, as in this published dipstick study. Read your result against the reference range printed on your own report.

• Negative: the expected result. UCSF describes a negative test as normal.
• Trace: a borderline reaction. Cleveland Clinic lists “negative or trace” as the normal finding for leukocyte esterase on a urinalysis. Cleveland Clinic’s urinalysis guide lists these values.
• 1+ to 3+ (small to large): a positive result that suggests white blood cells are in the urine and indicates a possible urinary tract infection. UCSF explains what an abnormal result means.

A higher grade means a stronger color reaction on the pad. No grade confirms an infection on its own: when the test is positive, the urine is typically examined under a microscope for white blood cells and other signs of infection. UCSF describes this follow-up.

Leukocyte esterase results at a glance

These are general patterns from the sources cited, not a diagnosis. Your symptoms and the rest of your urinalysis change what a result means.

UCSF, Cleveland Clinic, MedlinePlus, NIDDK, and AAFP cover these patterns.

What does it mean when leukocyte esterase and nitrite are both positive?

A positive leukocyte esterase with a positive urine nitrite points toward a urinary tract infection: leukocyte esterase is a sign of white blood cells, and nitrite is a sign of bacteria. Many bacteria that cause UTIs change nitrates in urine into nitrites, so nitrites in urine usually mean a UTI. MedlinePlus explains the nitrite test.

The two tests have opposite strengths. In studies summarized by the American Academy of Family Physicians, leukocyte esterase detected most culture-confirmed UTIs but was also often positive without one. Nitrite was rarely positive without an infection but missed many infections. AAFP’s urinalysis review summarizes this accuracy data. A negative nitrite therefore does not rule out a UTI, because some bacteria do not produce nitrites. MedlinePlus explains why.

Can a leukocyte esterase result be a false positive or false negative?

Yes. The dipstick can react without a urinary tract infection, and it can miss one.

Causes of a positive result without a UTI named by the cited sources:

• contamination of the sample, including vaginal secretions such as blood or heavy mucus discharge;
• Trichomonas infection (trichomoniasis).

UCSF lists these causes, and AAFP lists contamination.

Causes of a negative or weaker result despite a UTI named by the cited sources:

• high levels of protein or glucose (sugar) in the urine;
• ketones in the urine;
• very concentrated urine (high specific gravity);
• high vitamin C;
• some medicines, including cephalexin, nitrofurantoin, tetracycline, and gentamicin.

AAFP’s table of false results lists these, and UCSF names protein and vitamin C. Tell whoever orders the test about everything you take, but do not stop a medicine unless your provider tells you to. MedlinePlus gives the same instruction.

Timing matters too. Urine that sits for more than two hours before testing, without refrigeration, often gives unreliable results. AAFP notes this handling limit.

How do you collect a clean-catch urine sample?

A clean-catch (midstream) sample reduces the chance that germs or cells from the skin, penis, or vagina get into the urine and cause a misleading result. MedlinePlus describes these steps:

1. Wash your hands with soap and water and dry them.
2. Open the container without touching the inside.
3. Clean the genital area with the wipe provided. For a penis, wipe the head, pulling back the foreskin if you have one. For a vagina, separate the labia and wipe the inner sides from front to back.
4. Urinate into the toilet for a few seconds, then stop the flow.
5. Start urinating again into the container, without letting it touch your body.
6. Collect the amount marked on the container, then finish urinating into the toilet.
7. Cap the container and return it as instructed.

If you are having your period or have bleeding hemorrhoids, tell the lab or your provider before the test. MedlinePlus lists these instructions, and MedlinePlus also has a clean-catch guide.

Is leukocyte esterase the same as white blood cells in urine?

No. They are two measurements of the same question. Leukocyte esterase is a chemical dipstick test that detects an enzyme from white blood cells. The microscopic urine white blood cell count counts the cells directly under a microscope. A positive leukocyte esterase is usually followed by that microscopic exam. UCSF describes this sequence.

The two can disagree, because the dipstick has its own false positives and false negatives (see above). Microscopy also shows things the dipstick cannot, such as casts, crystals, and bacteria. AAFP’s review covers dipstick and microscopy together.

When does a positive result need prompt care?

A positive leukocyte esterase matters most when it comes with symptoms. Symptoms of a bladder infection include burning when you urinate, frequent or intense urges to urinate, lower abdominal pain or discomfort, and cloudy, bloody, or strong-smelling urine. Contact a health care professional if you have these symptoms. NIDDK lists bladder infection symptoms.

• Fever, chills, nausea, vomiting, or pain in the back, side, or groin can signal that an infection has spread to the kidneys. NIDDK advises that quick treatment is important in that case. NIDDK explains kidney infection warning signs.
• Pregnancy changes the approach. The US Preventive Services Task Force recommends screening pregnant people for bacteria in the urine with a urine culture, even without symptoms. USPSTF’s recommendation covers pregnancy.
• Repeat infections may lead to further tests, such as urinary tract imaging or cystoscopy, to look for a cause like a kidney stone. NIDDK describes testing for repeat infections.
• Older adults may have confusion, weakness, or fatigue instead of typical urinary symptoms. MedlinePlus lists these symptoms.

Whether antibiotics are needed is a decision for the treating clinician, and a urine culture often informs it. NIDDK explains the role of urine culture.

Without symptoms, the picture is different. For adults who are not pregnant, the USPSTF recommends against screening for bacteria in the urine. USPSTF explains that recommendation.

Frequently asked questions

Can leukocytes in urine be normal?

A negative result is the expected finding, and Cleveland Clinic lists “negative or trace” as normal for leukocyte esterase. Cleveland Clinic lists these values.

Does leukocyte esterase in urine always mean a UTI?

No. It suggests white blood cells are present, which is most often from a UTI, but vaginal secretions, Trichomonas infection, and contamination of the sample can also cause a positive result. UCSF lists these causes.

What does a positive leukocyte esterase with a negative urine culture mean?

White cells in urine without bacteria on a standard culture is called sterile pyuria. AAFP lists causes including Chlamydia and Ureaplasma infections, urethritis, kidney stones, exercise, some medicines such as corticosteroids, and less common kidney and bladder conditions. AAFP lists causes of sterile pyuria.

Can a vaginal infection or discharge cause leukocytes in urine?

Yes. UCSF names vaginal secretions, such as blood or heavy mucus discharge, and Trichomonas infection as causes of a positive result without a UTI. A careful clean-catch sample helps reduce this contamination. UCSF lists these causes.

Are at-home UTI test strips accurate?

Home strips check the same nitrite and white blood cell markers, but MedlinePlus notes they do not always give accurate results and can miss an infection. A lab urinalysis or urine culture gives a more complete picture. MedlinePlus covers at-home UTI tests.

Can you lower leukocytes in urine?

Leukocyte esterase is a sign of a cause, such as an infection, rather than a level to target on its own. For habits studied in urinary tract health, see how to improve your urine leukocytes naturally.

Testing leukocyte esterase with Mito

Leukocyte esterase is measured as part of a routine urinalysis, alongside urine nitrite and the other dipstick markers. It is also included in the Mito Core Panel.

Related urine markers

• Urine white blood cells (microscopic count)
• Urine nitrite
• How to improve your urine leukocytes naturally