Seeing white blood cells in urine on a lab report is one of the most common reasons people go looking for an explanation, and the number beside the line is rarely explained on the page itself. Most laboratories call 0 to 5 cells per high-power field a normal result, and anything above that range gets described as pyuria. That single number, though, does not tell you whether you have an infection: it tells you that immune cells have reached the urine somewhere between the kidneys and the point of collection. In this article you will learn how the reference range is built, how the leukocyte esterase square on the dipstick relates to the count seen under the microscope, which causes other than a urinary tract infection can raise the number, and what a clinician usually does next.
What white blood cells in urine actually represent
White blood cells, also called leukocytes, are the cells your immune system sends toward tissue that is irritated, injured, or infected. They circulate constantly in the bloodstream, and a full account of their role in blood work is covered in our guide to leukocyte blood test results. Urine is a different story: it starts as a filtrate of blood inside the kidneys, and healthy filtration leaves almost all cells behind. A handful of leukocytes still slips through or is shed from the lining of the urinary tract, which is why the normal range is a small number rather than zero.
When the count rises, it means leukocytes are being recruited somewhere along the path urine travels. That path is long. It runs from the filtering units of the kidney, down the ureters, into the bladder, and out through the urethra, and inflammation at any point can push cells into the sample. The bladder and urethra portion of that path is what clinicians call the lower urinary tract.
Why the cells are counted, not weighed
A urinalysis has three layers: a visual check of color and clarity, a chemical dipstick, and a microscopic examination of the sediment left after the sample is spun in a centrifuge. Leukocytes are reported from that third layer. A technologist or an automated analyzer looks at the sediment through a high-power objective and counts the cells visible in one field of view, then averages several fields. Because the result depends on how much urine was spun and how concentrated it was, the number is an estimate of concentration rather than an exact census. Our overview of urine microscopy results walks through the other elements reported alongside them.
The normal range for white blood cells in urine
Most United States laboratories report 0 to 5 white blood cells per high-power field as the reference range for a clean-catch sample. Some laboratories report 0 to 2, some report fewer than 10 for samples collected from people with catheters, and a few report cells per microliter of uncentrifuged urine instead, where roughly 10 cells per microliter is the usual cutoff. The units matter more than the number, so read the column beside your result before comparing it with anything you find online.
The table below shows how a raised count is generally described and what tends to follow. It is a guide to the vocabulary on your report, not a set of thresholds that decide treatment on their own.
| White blood cells per high-power field | How it is usually described | Typical next step |
|---|---|---|
| 0 to 2 | Normal, often written as none seen or rare | No further testing for this line |
| 3 to 5 | Still inside the reference range, sometimes flagged as borderline | Interpreted with your symptoms; usually nothing further |
| 6 to 10 | Mildly raised, mild pyuria | Checked against the dipstick and, if the sample looked contaminated, repeated |
| 11 to 25 | Clearly raised pyuria | A urine culture is commonly ordered when symptoms fit |
| More than 25, or too numerous to count | Marked pyuria | Culture plus assessment for kidney involvement or another inflammatory cause |
Two details are worth holding onto. First, a count on the high side with no symptoms is treated very differently from the same count in someone with burning and urgency. Second, a very dilute sample lowers the apparent count, which is why technologists read the result next to the specific gravity line that records how concentrated the urine was.
Reading the units on your report
Reports use several formats for the same finding. Cells per high-power field, abbreviated HPF, is the most common in the United States. Cells per microliter appears on automated analyzers. Some reports use semi-quantitative words instead of numbers, running from rare through few, moderate, and many. If your report mixes formats, the reference range printed beside the result is the one your laboratory validated, and it is the only one worth comparing your number against.
How leukocyte esterase relates to the microscopic count
The dipstick does not see cells. It carries a pad that detects leukocyte esterase, an enzyme released by neutrophils, the most numerous type of white blood cell. When leukocytes are present and have started to break down, the enzyme leaks into the urine and turns the pad purple. The result is reported as negative, trace, or one to three plus signs. Our dedicated page explains the chemistry and the pitfalls of leukocyte esterase test results in detail.
In practice the two results usually agree, and a positive dipstick is what prompts many laboratories to run the microscopic examination in the first place. Where they disagree is informative rather than alarming.
When the dipstick and the microscope disagree
A positive esterase pad with a low microscopic count often means the cells broke apart before the sample reached the analyzer, which happens when urine sat at room temperature for hours, or when the urine is very alkaline. The enzyme survives; the intact cells do not. Urine acidity is worth checking on the same report, since an alkaline sample destroys cells faster.
The opposite pattern, a negative pad with visible cells, occurs when the count is only slightly raised, when the urine is very concentrated, or when high levels of glucose, protein, or vitamin C interfere with the chemistry. High sugar in urine is common enough that many reports carry a note about the interference it causes. Because neither method is perfect on its own, a clinician who suspects infection also reads the nitrite square, which turns positive when certain bacteria convert dietary nitrate, and orders a culture when the picture is unclear.
Causes of a raised count beyond urinary tract infection
A bladder infection is the most frequent explanation, and the combination of raised leukocytes, a positive nitrite square, and bacteria in the sediment makes it likely. Anyone comparing symptoms should read our full guide to urinary tract infection symptoms and testing. But a raised count is a marker of inflammation, not a marker of bacteria, and several other situations produce it.
Kidney and urinary tract causes
Stones scrape and irritate the lining of the ureter and bladder as they move, and they commonly raise both leukocytes and red cells without any infection being present; our page on kidney stone symptoms and treatment describes the typical pattern. Interstitial nephritis, an allergic-type inflammation of the kidney tissue that is most often triggered by a medication, raises the count and frequently adds white cell casts to the sediment, a finding explained in our guide to urinary casts in test results. Longstanding kidney disease, an indwelling catheter, recent urological surgery, and a resolving infection that has already been treated can all leave leukocytes behind for a while.
Genital and sexually transmitted causes
Chlamydia and gonorrhea inflame the urethra and produce leukocytes in urine with a urine culture that grows nothing, because the standard culture does not detect these organisms. This is a well-recognized reason for a raised count in sexually active adults with urinary symptoms, and our article on chlamydia symptoms and treatment covers the specific testing required. In men, inflammation of the prostate produces a similar picture with pelvic discomfort, described in our guide to prostatitis symptoms and treatment. A pattern of raised leukocytes with a repeatedly negative culture has its own name and its own workup, set out on our page about sterile pyuria and its causes.
Explanations that are not disease at all
Strenuous exercise in the hours before collection raises leukocytes and sometimes protein and red cells too, and the effect fades within a day or two of rest. Fever from any source, dehydration, and menstruation can all nudge the number upward. The largest non-disease cause, though, is contamination: cells and secretions from the vulva, foreskin, or perineum enter the cup and are counted along with everything else. The giveaway is squamous epithelial cells in the same sediment, which is why laboratories report them, as explained in our page on epithelial cells in urine results. Yeast in the sample points the same way, toward vaginal rather than urinary origin.
What usually happens after a raised result
The first question a clinician asks is whether you have symptoms. Burning, urgency, frequency, cloudy or strong-smelling urine, flank pain, or fever change the meaning of the same number completely. The second question is whether the sample was collected cleanly. The third is what else the report shows: nitrite, bacteria, red cells, protein, and casts each pull the interpretation in a different direction.
A culture is the usual next test when infection is plausible. It grows whatever organism is present, identifies it, and tests which antibiotics work against it, and our guide explains how to read urine culture results. If the culture is negative and the leukocytes persist, testing usually widens to sexually transmitted infections, imaging for stones, a review of medications, and sometimes kidney function tests. Blood in the sample alongside leukocytes deserves attention on its own terms, particularly in adults over 40 or with a smoking history, and our page covers blood in urine test results.
When to see a doctor
Contact a clinician promptly if a raised leukocyte count comes with fever, chills, back or flank pain, nausea, or vomiting, since these suggest the kidneys are involved rather than the bladder alone. Seek care the same day if you are pregnant, have diabetes, have a weakened immune system, have a urinary catheter, or have had a kidney transplant, because infections progress faster in these situations. Book a routine appointment if the count stays raised across two samples, if there is visible blood, or if urinary symptoms persist despite a course of antibiotics.
Giving a sample that produces a reliable count
Because contamination is the most common reason for a falsely raised result, collection technique changes the number more than almost anything else. A clean-catch midstream sample means washing your hands, cleaning the genital area front to back with the wipe provided, starting to urinate into the toilet, then moving the cup into the stream partway through and removing it before you finish. Women are usually asked to hold the labia apart; uncircumcised men are asked to retract the foreskin.
Timing helps too. A first-morning sample is the most concentrated and therefore the most sensitive, though any sample works. Get the cup to the laboratory within an hour, or ask whether it should be refrigerated, since cells break down at room temperature and the microscopic count falls even as the esterase pad stays positive. Avoid heavy exercise the day before, and mention any recent antibiotic, any catheter, and where you are in your menstrual cycle. If you want a walk-through of the whole panel, the National Library of Medicine publishes an accessible reference on urinalysis and what it measures.
Latest scientific advances
Research over the past three years has focused less on changing the reference range and more on clarifying what a raised count does and does not prove. The findings below are summarized in plain language.
Pyuria is not the definition of an infection
A 2023 systematic review, which is a study that pools and compares the methods of many earlier studies, examined how 47 recent research trials defined a urinary tract infection. Only about a quarter of them required pyuria at all; most relied on symptoms, and about half required a positive culture. What this means for you is that a raised leukocyte count is treated as one input among several, and finding one on a report without symptoms is not the same as being diagnosed with an infection.
The dipstick and the laboratory count perform differently
A 2025 study in infants aged two to six months compared the point-of-care dipstick with a full laboratory urinalysis against culture results. The two approaches did not perform identically, and the researchers concluded that the choice of test affects how many infections are caught and how many false alarms are raised. What this means for you is that a dipstick done in a clinic room is a screening step, and a laboratory examination or a culture is what settles an uncertain result.
The same number means different things in different people
A 2024 study across two centers looked at children with spina bifida, a group in whom urinary tract infection is frequently overdiagnosed because many use catheters. Standard urinalysis findings, including pyuria, were far less reliable at identifying a genuine symptomatic infection in this group than in the general population. What this means for you is that context matters: a catheter, a neurological bladder condition, or a history of frequent infections all change how much weight a clinician gives to a raised count.
Newer markers are being tested alongside the leukocyte count
A 2024 study measured urinary calprotectin, a protein released by white blood cells, and compared it with dipstick pyuria for detecting meaningful bacterial growth. Calprotectin picked up signal in some samples where the dipstick did not, suggesting it may add information when leukocyte numbers are low. What this means for you is that this work is still preliminary and needs confirmation in larger groups before it changes routine testing, so calprotectin is not yet something to ask for.
Glossary
| Term | Definition |
|---|---|
| Leukocyte | The medical word for a white blood cell, one of the immune cells that travels to sites of infection or inflammation. |
| Pyuria | A white blood cell count in urine above the laboratory reference range. It describes the finding, not its cause. |
| High-power field (HPF) | One circular view of urine sediment seen through the higher magnification lens of a microscope. Counts are averaged across several fields. |
| Leukocyte esterase | An enzyme released by white blood cells that a dipstick pad detects chemically, without seeing the cells themselves. |
| Nitrite | A dipstick square that turns positive when certain bacteria convert dietary nitrate in the bladder. A negative result does not rule out infection. |
| Clean-catch midstream sample | A collection method in which the genital area is cleaned and only the middle portion of the urine stream is caught, to limit contamination. |
| Sterile pyuria | A raised white blood cell count with a urine culture that grows no ordinary bacteria. |
| Asymptomatic bacteriuria | Bacteria present in urine without urinary symptoms. In most adults it is not treated with antibiotics. |
| Interstitial nephritis | Inflammation of the kidney tissue between the filtering units, most often triggered by a medication or an infection. |
| Urine culture | A laboratory test that encourages any bacteria in the sample to grow, then identifies them and tests which antibiotics work. |
FAQ
Can you have leukocytes in urine but no infection?
Yes, and it is common. Kidney stones, inflammation of the kidney tissue from a medication, a sexually transmitted infection that a standard culture does not detect, recent strenuous exercise, fever, a catheter, and contamination of the sample during collection all raise the count without a routine bladder infection being present. When the culture comes back negative and the leukocytes remain, clinicians call the pattern sterile pyuria and look for these other explanations rather than repeating antibiotics.
What counts as a high level of white blood cells in urine?
Most laboratories treat more than 5 cells per high-power field as above the reference range, though the threshold varies with the collection method and the analyzer. Counts in the 6 to 10 range are usually described as mild, and counts above 25 as marked. The number on its own does not set the response: a mildly raised count with clear symptoms may prompt treatment, while a higher count with no symptoms may simply be repeated on a properly collected sample.
Do white blood cells in urine mean cancer?
Almost never on their own. Bladder and kidney cancers are far more commonly signaled by visible or microscopic blood in the urine than by leukocytes, and a raised white cell count in isolation is overwhelmingly caused by infection, stones, or contamination. That said, a persistent raised count with blood, in an adult over 40 or with a history of smoking, is a combination clinicians investigate further with imaging and sometimes a look inside the bladder.
What causes white blood cells in urine during pregnancy?
Pregnancy makes urinary tract infections more likely, because hormonal changes slow the flow of urine through the ureters. Vaginal discharge, which increases in pregnancy, is also a frequent source of contamination in the cup. Because untreated infection during pregnancy carries real risks, prenatal care in the United States includes urine screening, and a raised count is followed up more actively than it would be outside pregnancy. Report any burning, urgency, or back pain to your obstetric team promptly.
Can a sexually transmitted infection cause white blood cells in urine?
Yes. Chlamydia and gonorrhea inflame the urethra and are a classic cause of leukocytes in urine with a culture that grows nothing, because the standard culture is not designed to detect them. If you have urinary symptoms, a raised count, a negative culture, and any recent change in sexual partners, ask specifically about nucleic acid testing for these organisms on a urine sample. It is a simple test and it is not part of a routine urinalysis.
How do you lower white blood cells in urine naturally?
There is no home remedy that lowers the count directly, because the count reflects an underlying cause rather than being a condition in itself. What helps is addressing that cause: drinking enough fluid, not delaying urination, and completing any treatment your clinician prescribes. Cranberry products have been studied mainly for preventing repeat infections, not for clearing an existing one. If symptoms are present, waiting to see whether the number falls on its own is not a safe approach.
Sources
- MedlinePlus, National Library of Medicine — Urinalysis — MedlinePlus Medical Encyclopedia, reviewed 2025 — medlineplus.gov
- Cleveland Clinic — Urinalysis: What It Is, Purpose, Procedure, Results and Types — Cleveland Clinic, reviewed 2024 — my.clevelandclinic.org
- Mayo Clinic — Urinalysis — Mayo Clinic, 2023 — mayoclinic.org
- Bilsen MP, Jongeneel RMH, Schneeberger C, et al. — Definitions of Urinary Tract Infection in Current Research: A Systematic Review — Open Forum Infectious Diseases, 2023 — doi.org/10.1093/ofid/ofad332
- Hunt KM, Green RS, Sartori LF, et al. — Urine Dipstick for the Diagnosis of Urinary Tract Infection in Febrile Infants Aged 2 to 6 Months — Pediatrics, 2025 — doi.org/10.1542/peds.2024-068671
- Forster CS, Miller RG, Gibeau A, et al. — Accuracy of Urinalysis for UTI in Spina Bifida — Pediatrics, 2024 — doi.org/10.1542/peds.2023-065192
- Waldecker-Gall S, Waldecker CB, Babel N, et al. — Urinary calprotectin as a diagnostic tool for detecting significant bacteriuria — Scientific Reports, 2024 — doi.org/10.1038/s41598-024-62605-y
Further reading
- Compare the chemical screen with the cell count by reading our leukocyte esterase results guide.
- Explore what a raised count with a negative culture means in our sterile pyuria explainer.
- Check the square that points toward bacterial infection with our urine nitrite test guide.
- Identify what grows in a sample and which antibiotics work using our urine culture results guide.
- Review the bacteria line that sits beside the cell count in our bacteria in urine test guide.
Understand your lab results with BloodSense
A leukocyte count makes sense only next to the nitrite square, the bacteria line, the red cell count, and the epithelial cells that reveal how clean the sample was. BloodSense reads your urinalysis, urine culture, and related blood work together and explains in plain language what each line contributes and which combinations usually prompt a follow-up. It helps you understand your results and prepare better questions for your appointment; it does not diagnose, and it does not replace your clinician.
