Urine Leukocyte Esterase (Dipstick)

A dipstick check for an enzyme from white blood cells. A positive result can be a sign of inflammation in the urinary tract, such as a UTI.

AI-verified against cited sources. Awaiting expert reviewAlso called LE, LEULOINC 5799-2

What it is

Leukocyte esterase is an enzyme made by white blood cells called neutrophils. When many white cells are in your urine, a pad on the dipstick changes color. Results are reported as negative, trace, small, moderate or large (or 1+ to 3+), and some analyzers print cells per microliter. This is not a white blood cell count. A separate look under the microscope (urine WBC) counts the cells.

Why it matters

Clinicians use this test as a quick first check for inflammation in the urinary tract, most often a urinary tract infection (UTI). A positive result doesn't prove an infection, and a negative one doesn't completely rule it out. Your clinician weighs it with your symptoms, the nitrite result, a microscope exam and sometimes a urine culture.

If it’s high

A positive result means the dipstick found signs of white blood cells in your urine, called pyuria. The most common reason is a urinary tract infection, but a contaminated sample and several non-infectious causes can also do it. A positive result doesn't always mean an infection.

Common causes

A urinary tract infection (bladder or kidney infection)
A sample that picked up contamination during collection
Urethritis or other infections, including some sexually transmitted infections such as chlamydia
Kidney stones or a foreign body in the urinary tract
Hard exercise
Inflammation next to the urinary tract, such as appendicitis or diverticulitis
Some medicines, including corticosteroids and cyclophosphamide
Kidney inflammation, such as glomerulonephritis, and some autoimmune conditions
Less often, tuberculosis of the urinary tract, viral infections or bladder tumors

What can help

Give a midstream clean-catch sample, following the steps on the collection kit
Tell your clinician about symptoms such as burning when you pass urine, needing to go often or urgently, or pain in your lower belly or side
Ask whether a repeat sample or a urine culture is needed
Mention recent antibiotics and vitamin C supplements, since both can change the result

What can affect your result

How the sample was collected: contamination can raise the result, and a midstream clean-catch sample lowers that risk
Menstruation: tell the person collecting the sample if you are having a period
Hard exercise
Vitamin C, very concentrated urine, glucose, ketones or protein in the urine, and some antibiotics can lower the reading
Strip brand and timing: each brand has its own read time and grading steps
A contaminated sample can cause a false-positive result; a midstream clean-catch sample lowers the risk.
Vitamin C, very concentrated urine, and glucose, ketones or protein in the urine can make the reading lower than it should be.
Some antibiotics (cephalexin, nitrofurantoin, tetracycline, gentamicin) can also lower the reading.
The pad needs 30 seconds to 2 minutes to develop depending on the brand, so reading it too early can under-read.
Strongly colored urine, such as from phenazopyridine, can interfere with the color pads.

Any time. A midstream clean-catch sample is preferred, and the sample should be examined within about two hours or kept refrigerated. Reflects white cells in urine since your bladder was last emptied, so it follows changes over hours.

When to talk to a clinician

See a clinician soon if a positive result comes with symptoms such as burning or pain when you pass urine, needing to go often or urgently, or lower belly pain. Contact a clinician right away if you also have fever, nausea, vomiting, shaking chills or pain in your belly, side or back, if you can't pass urine, or if you are passing blood clots.

Questions you could ask

Should my leukocyte esterase be read together with my nitrite and microscope results?
Should we send a urine culture or repeat the test with a clean-catch sample?
Could the way I collected the sample explain this result?
What symptoms should make me call you?

Questions people ask

Does a positive leukocyte esterase mean I have a UTI?

Not by itself. It means white blood cells or their enzyme were found in your urine. A urinary tract infection is a common reason, but a contaminated sample, exercise, kidney stones and several other conditions can also cause it. Clinicians read it with your symptoms, the nitrite test, a microscope exam and sometimes a urine culture.

Can my result be negative even though I have symptoms?

Yes. The strip can miss some cases, and vitamin C, very concentrated urine or some antibiotics can lower the reading. If you have symptoms, tell your clinician even when the strip is negative.

What is the difference between leukocyte esterase and WBC in urine?

Leukocyte esterase is a chemical clue on the dipstick. 'WBC' on a urinalysis usually comes from looking at the urine under a microscope and counting cells. They often agree, but not always.

My result is positive but I have no symptoms. What does that mean?

Several things can cause a positive strip without symptoms, including a sample that picked up contamination. Whether anything more is needed depends on your symptoms, your other results and your situation, so it is a good question to bring to your clinician.

How do I give a good sample?

Wash your hands, clean the genital area with the wipe you were given, start urinating into the toilet for a few seconds, then catch the middle of the stream in the container without touching the inside. Finish in the toilet and return the sample as instructed. If you are having your period, tell the person collecting it.

Show the science and sources

For clinicians and researchers

Leukocyte esterase is produced by neutrophils, and the pad develops over 30 seconds to 2 minutes depending on the brand (AAFP). It detects pyuria, not bacteria, and is read together with nitrite. In studies reviewed by AAFP (2005), a positive leukocyte esterase had a sensitivity of 72 to 97% and a specificity of 41 to 86% for culture-confirmed UTI, and a positive leukocyte esterase or nitrite had a sensitivity of 46 to 100% and a specificity of 42 to 98%. A 2026 narrative review describes leukocyte esterase and nitrite as the main dipstick markers for UTI and notes that their performance varies with pathogen, urine concentration and patient factors, and that other conditions also raise leukocytes. False positives come from contamination; false negatives from elevated specific gravity, glycosuria, ketonuria, proteinuria, oxidizing drugs (cephalexin, nitrofurantoin, tetracycline, gentamicin) and vitamin C. Causes of sterile pyuria include urethritis (Chlamydia, Ureaplasma), tuberculosis, bladder tumors, viral infection, nephrolithiasis, foreign bodies, exercise, glomerulonephritis, and corticosteroid or cyclophosphamide use. Labcorp notes that leukocyturia may reflect genitourinary inflammation, glomerulonephritis, autoimmune disease or adjacent inflammation such as appendicitis or diverticulitis. On the Siemens Multistix strip read in one 2019 study, steps corresponded to trace 15, + 70, ++ 125 and +++ 500 leukocytes/µL; other brands differ. Quest lists 'Negative' as the expected result for Urinalysis, Complete (5463), with urine WBC by microscopy at 5 or fewer per high-power field. Labcorp's urinalysis (003772) reports it as 'WBC Esterase' under LOINC 5799-2.

LOINC 5799-2 (primary), 60026-2, 105103-6, 110367-0, 27297-1. Specimen: urine.

Sources

Urinalysis: A Comprehensive Review, American Family Physician (2005)
Urinalysis (MedlinePlus Medical Encyclopedia), MedlinePlus, U.S. National Library of Medicine (2025)
Urine - bloody (MedlinePlus Medical Encyclopedia), MedlinePlus, U.S. National Library of Medicine (2025)
Diagnostic tests for urinary tract infections and antimicrobial resistance—a reality check between diagnostic innovation and implementation: a critical narrative review, Frontiers in Cellular and Infection Microbiology (2026)
Ketones in Urine (MedlinePlus Medical Test), MedlinePlus, U.S. National Library of Medicine
Urinalysis, Complete (test code 5463), Quest Diagnostics
Urinalysis, Complete With Microscopic Examination (test 003772), Labcorp
Evaluation of the Clinitek, a point-of-care urinalysis system for the measurement of clinically significant urinary metabolites and detection of haematuria in Schistosoma haematobium infected children in southern Côte d'Ivoire, Parasites & Vectors (2019)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.