Lab result explainedUrinalysisLast updated November 10, 2026

Leukocytes in urine: the normal range, what a high white blood cell count means and causes

Leukocytes (white blood cells) in urine (Urine WBC) · Urinalysis (microscopy) · reported in WBC per high-power field (WBC/hpf) on spun sediment; some automated analyzers report cells per microlitre (cells/µL)

Leukocytes in urine are white blood cells that have moved from the bloodstream into the urinary tract, and a urinalysis counts them under the microscope, reported as white blood cells per high-power field (WBC/hpf). The normal range is 0 to 5 per high-power field (some labs use 0 to 2, and automated analyzers report under 10 cells per microlitre). More than that is called pyuria, and the two most common reasons for it are a urinary tract infection and contamination of the sample by vaginal secretions, which carry white cells of their own.

This page is about the microscopic cell count. The dipstick pad that turns purple for white cells measures leukocyte esterase, an enzyme the cells release; the two usually agree, but the count is the more precise test and is what the lab uses to confirm a positive strip. A count of 6 to 10 is borderline. Counts above 10 with burning, urgency and frequency almost always mean cystitis, and counts above 50 to 100 are typical of a kidney infection or an abscess.

White cells in urine without bacteria or with a negative culture, often searched as leukocytes in urine with no infection, is called sterile pyuria. It is common and has a long list of explanations: a recently treated infection, chlamydia or another sexually transmitted infection, a kidney stone, interstitial cystitis, prostatitis, an allergic reaction to a medicine in the kidney, and simple contamination. This is why a high white-cell count sometimes leads to more questions rather than an antibiotic.

Urine WBC at a glance

What it is: white blood cells, mostly neutrophils, counted under the microscope in a spun urine sample; a direct measure of inflammation in the urinary tract.
Normal range: 0 to 5 WBC per high-power field (some labs 0 to 2); on automated counters under 10 cells per microlitre. Labs differ, so use the printed range.
6 to 10 WBC/hpf is borderline; more than 10 is pyuria and usually means infection or inflammation. More than 50 to 100 suggests kidney infection, abscess or a stone with infection.
High white cells with bacteria, nitrite and symptoms is a UTI; high white cells with a negative culture (sterile pyuria) points to an STI, a recently treated infection, a stone, interstitial cystitis, prostatitis or contamination.
A high count with no symptoms is not automatically treated; asymptomatic bacteriuria is left alone except in pregnancy and before urologic surgery.
Next step: a clean-catch repeat with a urine culture if there are symptoms; STI testing, imaging or urology review if white cells persist with negative cultures.

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What Urine WBC measures

White blood cells, overwhelmingly neutrophils, leave the capillaries and migrate into the urinary tract whenever its lining is infected, inflamed or injured. To count them, the lab centrifuges about 10 mL of urine, discards most of the fluid, resuspends the sediment and examines it at 400x magnification. The technologist counts the cells in several fields and reports an average or a range per high-power field. Automated analyzers instead pass unspun urine through a flow cell or a camera system and report cells per microlitre; roughly 10 cells per microlitre of unspun urine corresponds to 5 per high-power field of spun sediment, though the conversion is approximate.

Three details on the report refine the count. White-cell clumps (several cells stuck together) are strongly associated with bacterial infection. White-cell casts, cylinders of white cells molded in a kidney tubule, mean the inflammation is in the kidney itself, as in pyelonephritis or interstitial nephritis, rather than the bladder. And the number of squamous epithelial cells tells you whether the sample is trustworthy: more than 15 to 20 per low-power field means genital contamination, and the white cells may have come from the vagina or foreskin rather than the urinary tract.

The count depends on how the sample was handled. White cells break down in urine that is dilute, alkaline or left at room temperature for more than two hours, so an old sample under-counts them. Very concentrated urine, menstruation, vaginal discharge and a sample taken from the start of the stream all over-count. A midstream clean catch, tested within two hours or refrigerated, gives the most reliable result.

Normal range for Urine WBC

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

Group	Typical range (WBC per high-power field (WBC/hpf) on spun sediment; some automated analyzers report cells per microlitre (cells/µL))	Notes
0–2 WBC/hpf	Normal	Typical result in men and in a well-collected sample from a woman without symptoms.
3–5 WBC/hpf	Normal (upper end)	Within most labs' reference range, especially in women. Repeat only if symptoms are present.
6–10 WBC/hpf	Borderline	Often contamination, an early or resolving infection, or mild inflammation. Interpreted with squamous cells, nitrite, bacteria and symptoms.
11–20 WBC/hpf	Pyuria (abnormal)	With symptoms and bacteria, a bladder infection is likely. With a negative culture, consider STI, stone, interstitial cystitis or recent antibiotics.
21–50 WBC/hpf	Marked pyuria	Common in acute cystitis and kidney infection; also seen with a stone, prostatitis or an infected catheter.
More than 50 WBC/hpf, or too numerous to count	Heavy pyuria	Suggests kidney infection, abscess, severe cystitis or an obstructed infected kidney, particularly with fever.
Automated counters	Under 10 cells/µL normal; 10–25 borderline; above 25 abnormal	Cut-offs vary by analyzer; 10 cells/µL of unspun urine is the research definition of pyuria.
White-cell clumps or white-cell casts	Abnormal at any count	Clumps favor bacterial infection; white-cell casts place the inflammation in the kidney (pyelonephritis, interstitial nephritis).
Squamous epithelial cells above 15–20 per low-power field	Contaminated sample	The white-cell count cannot be trusted; repeat with a clean catch.

High leukocytes (white blood cells) in urine

A white-cell count above the lab's range means something is inflaming the lining of the urinary tract. In an otherwise healthy woman with burning, urgency and frequency, more than 10 WBC/hpf together with bacteria on microscopy or a positive nitrite makes a bladder infection very likely, and a culture usually confirms it. Counts above 50, fever, flank pain or white-cell casts shift the picture to the kidney. In men, children and pregnant women, any clear pyuria with symptoms is taken seriously and cultured, because infections in these groups are more often complicated.

White cells without symptoms are a different matter. Up to 20 percent of women over 80, many residents of care homes, most people with diabetes and poor glucose control, and nearly everyone with a long-term catheter have white cells and bacteria in their urine with no illness. The Infectious Diseases Society of America advises against treating this asymptomatic bacteriuria, because antibiotics do not help and breed resistance, with two exceptions: pregnancy, where it is screened for and treated to prevent kidney infection and preterm birth, and before procedures that will cut or scope the urinary tract.

White cells with a negative culture, sterile pyuria, is a recognized clinical problem rather than a reassuring result. In sexually active adults the leading cause is chlamydia, gonorrhea, Mycoplasma genitalium or trichomonas, none of which grow on a routine urine culture. Other causes are an infection treated in the past two weeks (cells take days to clear), a kidney stone, interstitial cystitis, prostatitis, an allergic kidney reaction to antibiotics, proton-pump inhibitors or NSAIDs (interstitial nephritis), genitourinary tuberculosis, a bladder tumor, pelvic inflammatory disease or appendicitis lying against the bladder, lupus nephritis, a urinary catheter, and contamination. The pattern, the history and a few targeted tests usually sort out which.

Common causes

Bladder infection (acute cystitis)
Bacteria, most often E. coli, attach to the bladder lining and draw in neutrophils. This is the most common cause of pyuria in women; nitrite and bacteria are usually present and symptoms are typical.
Contamination from vaginal secretions, menstrual blood or foreskin
Vaginal discharge, bacterial vaginosis, yeast infection and smegma all contain white cells. The clue is many squamous epithelial cells; the fix is a clean-catch repeat.
Kidney infection (pyelonephritis)
Infection that has reached the kidney produces heavy pyuria, often white-cell casts and clumps, fever, flank pain and a raised blood neutrophil count and CRP.
Sexually transmitted urethritis
Chlamydia, gonorrhea, Mycoplasma genitalium and trichomonas inflame the urethra and give white cells with a negative routine culture, the classic cause of sterile pyuria in adults under 40.
Kidney stones
A stone scrapes and inflames the ureter or bladder, drawing in white cells and red cells with or without infection; pain in the flank radiating to the groin is typical.
Interstitial cystitis, radiation cystitis and bladder tumors
Non-infectious inflammation of the bladder wall produces persistent white cells with negative cultures; persistent pyuria with blood in anyone over 40 needs urology review and cystoscopy.
Prostatitis and epididymitis in men
An inflamed prostate or epididymis sheds white cells into urine, often with pelvic or testicular pain; pyuria in a man is always cultured and usually investigated further.
Drug-induced interstitial nephritis
An allergic reaction in the kidney to penicillins, cephalosporins, fluoroquinolones, proton-pump inhibitors, NSAIDs or allopurinol causes sterile pyuria, sometimes with eosinophils in the urine, a rising creatinine, rash and fever.
Urinary catheter, asymptomatic bacteriuria and diabetes
A catheter irritates the urethra and nearly always produces white cells and bacteria. Asymptomatic bacteriuria with pyuria is common in older women, residents of care homes and people with diabetes, and is not treated unless symptomatic.
Tuberculosis, fungal infection, lupus nephritis and other systemic disease
Genitourinary tuberculosis is the classic cause of persistent sterile pyuria with an acidic urine; Candida in immunosuppressed people, lupus nephritis, Kawasaki disease in children and inflammation next to the bladder (appendicitis, diverticulitis, pelvic inflammatory disease) also raise white cells.

Symptoms that can go with it

Burning or stinging when passing urine
Urgency, needing to go far more often, passing small amounts
Pressure, ache or cramping low in the belly or pelvis
Cloudy, strong-smelling or blood-tinged urine
Fever, chills, nausea, vomiting or pain in the flank or back (kidney involvement)
Vaginal or penile discharge, or pain at the urethral opening (suggests an STI or contamination)
In older adults: new confusion, falls, reduced appetite or drowsiness with few urinary symptoms
No symptoms at all (asymptomatic bacteriuria or a contaminated sample)

Read it alongside

Leukocyte esterase — the dipstick enzyme test for the same cells; a positive strip with a normal count suggests cells that have already broken down or a false positive, and a negative strip with a high count can occur with vitamin C or antibiotics in the urine.
Nitrite — positive nitrite with white cells is strong evidence of a gram-negative bacterial UTI; negative nitrite does not exclude infection because many organisms do not produce it.
Bacteria on microscopy and urine culture — the culture decides whether an infection is present (usually 100,000 colony-forming units per mL, or lower with symptoms) and which antibiotic works; a negative culture with white cells defines sterile pyuria.
Squamous epithelial cells — more than 15 to 20 per low-power field means the sample is contaminated and the white-cell count cannot be relied on.
Blood in urine — white cells with red cells suggest infection or a stone; blood that persists after the white cells clear needs its own work-up.
Protein in urine — more than a trace of protein with white cells raises the possibility of kidney inflammation (pyelonephritis, interstitial nephritis, glomerulonephritis) rather than simple cystitis.
Hyaline casts and white-cell casts — white-cell casts place the problem in the kidney; hyaline casts alone are usually benign.
Neutrophils, CRP and creatinine in blood — a rising neutrophil count or CRP suggests infection beyond the bladder; a rising creatinine with sterile pyuria suggests interstitial nephritis.

What usually happens next

If you have symptoms of a bladder infection and the count is above 10 WBC/hpf, most clinicians treat and send a culture, which takes 24 to 72 hours to identify the organism and its antibiotic sensitivities.
If you have no symptoms, the usual advice is to repeat with a careful midstream clean-catch sample rather than treat; the exceptions are pregnancy and planned urologic surgery.
If the culture is negative and white cells persist, expect a first-catch urine test for chlamydia, gonorrhea and Mycoplasma genitalium, a review of recent antibiotics and other medicines, and sometimes an ultrasound or CT scan for stones.
Persistent sterile pyuria with blood, with weight loss, or in anyone over 40 leads to urology referral for cystoscopy and imaging; with an acidic urine and night sweats, tuberculosis cultures are sent.
Ask: was this a clean catch, how many squamous cells were there, was nitrite positive, is a culture pending, and do I need treatment given my symptoms?
In pregnancy, a positive screening culture is treated even without symptoms, and a repeat culture is done after treatment to confirm it has cleared.

Diet, lifestyle and natural levers with evidence

What can move Urine WBC once the cause is known. Nothing here replaces finding the cause.

Drink more water if you get recurrent bladder infections

Moderate evidence

In a 12-month randomised trial of 140 premenopausal women with at least three cystitis episodes a year who normally drank under 1.5 liters a day, adding 1.5 liters of water daily roughly halved infections (1.7 versus 3.2 episodes per year) and antibiotic courses. More frequent voiding flushes bacteria before they can establish, which lowers the white-cell count over time.

Not a treatment for an active infection with fever or flank pain. People with heart failure, advanced kidney disease or on fluid restriction should check first.

Cranberry (juice or proanthocyanidin capsules)

Moderate evidence

A 2023 Cochrane review of 50 randomised trials found cranberry products reduced symptomatic, culture-verified UTIs by about 26 percent in women with recurrent infections and by about 54 percent in children, with no clear benefit in older people in care homes or people with catheters or neurogenic bladders. Proanthocyanidins stop E. coli attaching to the bladder lining; most positive trials used about 36 mg a day.

Prevention only; it does not treat an existing infection. Sweetened juice adds sugar, and cranberry can increase the effect of warfarin.

D-mannose

Preliminary evidence

An early 6-month trial of 308 women found 2 g of D-mannose a day cut recurrent UTIs from 60 percent on no treatment to 15 percent, similar to nitrofurantoin. However, a larger 2024 placebo-controlled trial of 598 women in UK general practice found no significant difference (51 percent versus 56 percent had a further infection over 6 months). The sugar is thought to coat E. coli so it cannot bind the bladder wall, but the evidence is now mixed.

Generally well tolerated; loose stools at higher doses. It is a sugar and may slightly affect glucose readings in diabetes.

Collect a clean catch and test it promptly

Strong evidence

This changes the number more than anything else. Midstream samples collected after cleaning, with the labia separated or foreskin retracted, have far fewer contaminating squamous cells and white cells than samples caught from the start of the stream, and contamination rates of 20 to 40 percent in routine samples fall sharply with instruction. Samples tested within two hours, or refrigerated, avoid both the loss of white cells in old urine and overgrowth of bacteria.

Avoid collecting during a period or within a few hours of sex, vaginal creams or lubricant. Vitamin C supplements can give a falsely negative dipstick but do not change the microscopic count.

When to see a clinician promptly

White cells in urine with fever above 100.4°F (38°C), shaking chills, flank or back pain, vomiting or confusion: possible kidney infection or sepsis, needs same-day assessment and urgent care if you cannot keep fluids down or feel faint.
Any urinary symptoms with white cells in pregnancy, in a man, in a child, or in anyone with diabetes, a kidney transplant, one kidney or a weakened immune system.
Burning, urgency or frequency lasting more than two days, or symptoms returning within two weeks of finishing antibiotics.
White cells that persist on two samples with a negative culture, especially with blood in the urine, weight loss, night sweats or age over 40.
White cells with a new rash, joint pains, a rising creatinine or recent start of an antibiotic, proton-pump inhibitor or NSAID: possible interstitial nephritis.
Severe one-sided pain spreading to the groin with white cells and blood, or inability to pass urine: possible obstructing stone with infection, an emergency.

Frequently asked questions

What is the normal range for leukocytes in urine?

Most labs report 0 to 5 white blood cells per high-power field as normal; some use 0 to 2, and automated analyzers use fewer than 10 cells per microlitre. Women tend to run slightly higher than men because of genital contamination. More than 10 per high-power field is called pyuria and usually means inflammation or infection, but always check the printed range on your own report because cut-offs differ.

What does a high WBC count in urine mean?

It means white blood cells are entering the urinary tract, most often because of a bladder infection. If you have burning, urgency and frequency and the report also shows bacteria or a positive nitrite, a UTI is the likely answer and a culture confirms it. If the culture is negative, the cells may come from a sexually transmitted infection, a recently treated infection, a kidney stone, interstitial cystitis, prostatitis, a medication reaction in the kidney or simple contamination.

What causes leukocytes in urine with no infection?

This is sterile pyuria. The most common causes are a contaminated sample (vaginal discharge or foreskin secretions), an infection treated within the past two weeks, chlamydia or another STI that does not grow on a standard culture, a kidney stone, interstitial cystitis, prostatitis, and an allergic kidney reaction to a medicine. Less common causes include genitourinary tuberculosis, bladder tumors, lupus nephritis and inflammation next to the bladder such as appendicitis.

Is 10, 20 or 50 WBC in urine high?

Yes. Ten per high-power field is the usual threshold for pyuria; 10 to 20 is mild and often a bladder infection or contamination; 20 to 50 is moderate and typical of cystitis; above 50 suggests a kidney infection, abscess or an infected stone, especially with fever or flank pain. The number alone does not decide treatment; your symptoms, the nitrite and bacteria results and the culture do.

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

Leukocytes are the cells themselves, counted under a microscope. Leukocyte esterase is an enzyme those cells release, detected by a dipstick pad that turns purple. The dipstick is a quick screen (about 75 to 95 percent sensitive); the microscopic count is the confirmation. They usually agree, but the dipstick can be positive when the cells have already broken apart, and falsely negative when the urine contains vitamin C, high glucose or certain antibiotics.

Are leukocytes in urine during pregnancy serious?

They need checking but are often contamination from increased vaginal discharge. Pregnant women are screened with a urine culture early in pregnancy because bacteria in the urine, even without symptoms, raise the risk of kidney infection and preterm birth and are treated. If your prenatal urinalysis shows white cells, expect a clean-catch repeat and a culture; if the culture is negative and you have no symptoms, no treatment is needed.

Should white blood cells in urine be treated if I have no symptoms?

Usually not. White cells and bacteria without symptoms (asymptomatic bacteriuria) are common in older women, people with diabetes and anyone with a catheter, and the Infectious Diseases Society of America recommends against antibiotics because they do not improve outcomes and drive resistance. The exceptions are pregnancy and the days before a procedure on the urinary tract. A repeat clean-catch sample is the usual next step.

How long do white blood cells stay in urine after a UTI is treated?

Typically a few days to a week after the bacteria are cleared, sometimes longer. A urinalysis repeated within a week of finishing antibiotics often still shows white cells with a sterile culture, which does not mean treatment failed if symptoms have gone. A repeat culture after treatment is only routine in pregnancy; otherwise a repeat is reserved for symptoms that persist or return.

References

Urinalysis. MedlinePlus, US National Library of Medicine (2023)View source
Urinalysis. Mayo Clinic (2023)View source
Urinalysis. Merck Manual Professional Version (2024)
Simerville JA, Maxted WC, Pahira JJ. Urinalysis: a comprehensive review. American Family Physician (2005)
Wise GJ, Schlegel PN. Sterile pyuria. New England Journal of Medicine (2015)
Nicolle LE, Gupta K, Bradley SF, et al.. Clinical practice guideline for the management of asymptomatic bacteriuria: 2019 update by the Infectious Diseases Society of America. Clinical Infectious Diseases (2019)
Schmiemann G, Kniehl E, Gebhardt K, Matejczyk MM, Hummers-Pradier E. The diagnosis of urinary tract infection: a systematic review. Deutsches Ärzteblatt International (2010)
Bent S, Nallamothu BK, Simel DL, Fihn SD, Saint S. Does this woman have an acute uncomplicated urinary tract infection?. JAMA (2002)
Owens DK, Davidson KW, Krist AH, et al.. Screening for asymptomatic bacteriuria in adults: US Preventive Services Task Force recommendation statement. JAMA (2019)
Hooton TM, Vecchio M, Iroz A, et al.. Effect of increased daily water intake in premenopausal women with recurrent urinary tract infections: a randomized clinical trial. JAMA Internal Medicine (2018)
Williams G, Hahn D, Stephens JH, Craig JC, Hodson EM. Cranberries for preventing urinary tract infections. Cochrane Database of Systematic Reviews (2023)
Hayward G, Mort S, Hay AD, et al.. D-mannose for prevention of recurrent urinary tract infection among women: a randomized clinical trial. JAMA Internal Medicine (2024)

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.