Leukocytes in Urine: Causes, Symptoms, Diagnosis, and Treatments

Leukocytes are an important part of the immune system that help fight off infection and disease in the body. Usually, only a small number of leukocytes are present in the urine. However, an increased level of leukocytes in the urine can indicate inflammation or infection of the urinary tract, kidneys, or other structures.

Understanding the implications of leukocytes in urine can help guide proper treatment to resolve the underlying condition. This comprehensive overview covers the details of how leukocytes end up in urine, the associated symptoms, and when to see a doctor.

What Are Leukocytes and What Do They Do?

Leukocytes, often called white blood cells (WBCs), are one of the main types of immune cells involved in the body’s response to invasion by foreign organisms or pathogens. The primary role of leukocytes is to defend the body from infection and fight disease.

There are several different types of leukocytes, including:

  • Neutrophils – The most common type of white blood cell that engulfs and destroys bacteria and fungi
  • Lymphocytes – Include both T cells and B cells involved in the immune response
  • Monocytes – Large WBCs that can ingest microbes and become macrophages
  • Eosinophils – Help fight parasites and control allergic reactions
  • Basophils – Secrete histamine and other chemicals during inflammatory reactions

Normally, leukocytes circulate in the bloodstream and lymphatic system. However, with an infection or inflammatory response, they can move into tissues and organs where pathogens, damaged cells, or other irritants are located. Higher than normal levels of leukocytes may enter the kidneys or urinary tract when fighting an infection in those areas.

What Do Leukocytes in Urine Mean?

The presence of leukocytes in urine, known as leukocyturia, usually indicates some type of inflammation, irritation, or infection occurring in the kidneys, bladder, ureters, urethra, or other areas of the urinary tract.

Some key points about what leukocytes in urine typically signify:

  • An elevated level of leukocytes is abnormal and requires further evaluation to determine the cause.
  • It often means there is an inflammatory response to an infection somewhere in the urinary system. Common infections that cause leukocytes in urine include urinary tract infections (UTIs), kidney infections, prostatitis, and some sexually transmitted diseases.
  • Non-infectious inflammatory conditions like interstitial cystitis and autoimmune disorders can also lead to increased leukocytes in the absence of infection.
  • Particularly high leukocyte counts usually correlate with more active or severe inflammation and infection.
  • The more leukocytes present, the more likely a bacterial infection is the underlying cause rather than just irritation or injury alone.
  • The presence of nitrites and bacteria in urine along with leukocytes further points to a UTI or kidney infection.
  • For women, leukocytes in urine most often indicate a UTI, while in men they may signal an inflamed prostate or STD like chlamydia.
  • Symptoms accompanying leukocyturia can help identify the location of inflammation such as the bladder or kidneys.
  • Persistent leukocytes without infection may be a sign of kidney disease, damage, or cancer needing evaluation.

In general, leukocytes in urine are a key indicator that further diagnostic tests and prompt medical care are required to determine the cause and guide appropriate treatment.

Leukocytes in Urine
Leukocytes in Urine: Symptoms, Causes & Treatments

What Causes Leukocytes in the Urine?

A variety of conditions can prompt leukocytes to appear in the urine, signaling inflammation or infection of part of the urinary system. Some of the most common causes include:

1. Infections

  • Urinary tract infections (UTIs) – The most frequent cause of leukocytes in urine, resulting from bacteria infecting anywhere along the urinary tract including the urethra, bladder, ureters, or kidneys. Women tend to get UTIs more often due to their shorter urethras.
  • Kidney infections (pyelonephritis) – Bacterial infection of one or both kidneys, typically caused by E. coli traveling up from the bladder. Can cause flank pain, fever, chills, nausea, and vomiting along with leukocytes and bacteria in the urine.
  • Prostatitis – Inflammation of the prostate gland, sometimes from a bacterial infection. May prompt leukocytes and bacteria to enter the urinary tract.
  • Sexually transmitted diseases (STDs) – Chlamydia, gonorrhea, trichomoniasis, and other STDs can infect the urethra, reproductive tract, or pelvic region, resulting in inflammation and leukocytes in urine.

2. Inflammatory Disorders

  • Interstitial cystitis – Chronic inflammation of the bladder lining resulting in pelvic pain, increased urinary frequency and urgency, and other symptoms along with recurrent leukocytes without infection. More common in women.
  • Autoimmune conditions – Diseases like lupus, rheumatoid arthritis, or Sjogren’s syndrome that involve immune system attacks on the body’s own tissues can sometimes affect the kidneys and urinary system, leading to leukocytes in urine.

3. Structural Abnormalities

  • Kidney stones – Sharp crystalline masses that form in the kidneys and can pass down into the ureters and bladder, cutting and irritating tissue along the way and prompting leakage of leukocytes into the urine.
  • Benign prostatic hyperplasia (BPH) – Noncancerous enlargement of the prostate that may obstruct urine flow and cause inflammation resulting in leukocytes.
  • Bladder stones – Mineral buildups in the bladder that can irritate the lining and trigger inflammation. More common in men.
  • Bladder diverticula – Small pouches or sacs that protrude from weak spots in the bladder wall, which can collect urine and become inflamed and infected.
  • Bladder fistula – An abnormal opening between the bladder and a nearby structure like the vagina or rectum, allowing leakage of urine and sometimes bacteria that can prompt leukocytes.

4. Cancers

  • Bladder cancer – Can cause inflammation, irritation, and leukocytes as tumors develop in the bladder lining. More common in men over age 55 who smoke.
  • Kidney cancer – Tumors in the kidneys may bleed or release chemicals leading to inflammation and leukocytes in urine. Usually occurs over age 60.
  • Prostate cancer – Advanced prostate cancer can spread to and block parts of the urinary tract, causing inflammation that results in leukocyturia.

5. Other Causes

  • Injury to the urinary tract – Damage from trauma, medical procedures like catheterization, kidney injury, etc. can prompt inflammation and leakage of leukocytes into the urine.
  • Vigorous exercise – Extreme physical exertion can temporarily result in a small amount of leukocytes and protein in urine, called “athlete’s urine.” Harmless unless chronic.
  • Unknown cause – In some cases, no specific cause can be found for the recurrent or persistent presence of leukocytes without infection. Further testing is needed.

What Symptoms May Occur with Leukocytes in Urine?

Some possible symptoms associated with increased leukocytes in the urine include:

  • Cloudy or foul-smelling urine – Due to the discharge of leukocytes, bacteria, pus, or blood into the urine.
  • Burning with urination – Pain or stinging sensation while peeing called dysuria, resulting from inflammation or irritation.
  • Increased urge/frequency – Needing to urinate more often with greater urgency, which may involve only small amounts.
  • Pelvic pain or discomfort – Aching sensations in the abdomen, pelvis, sides, lower back, or groin area.
  • Visible blood in urine – Pink, red, or brownish urine color from bleeding into the urinary tract.
  • Low-grade fever – Slightly elevated temperature up to about 101°F indicating possible infection.
  • Chills, fatigue, and weakness – Can accompany fever with a spreading kidney infection.
  • Lower back/flank pain – May signal kidney inflammation or infection on one or both sides.

However, leukocytes may also be present without any noticeable symptoms, especially with recurring, chronic, or minor cases. Symptoms often depend on the underlying cause.

How Are Leukocytes Detected in Urine?

Doctors have a few different tests they can use to check for the presence of elevated leukocytes in urine:

  • Urinalysis – A routine urine dipstick test followed by microscopic examination detects leukocytes, as well as indicators of infection like nitrites and bacteria.
  • Urine culture – Lab analysis where the urine sample is cultured to grow and identify any pathogenic bacteria or fungi causing an infection.
  • Cytology – Microscopic inspection and staining of urine sediment to analyze cells, which can reveal abnormal leukocyte counts.
  • Flow cytometry – Advanced technique that rapidly counts and classifies cells in a urine sample using fluorescent tags.
  • Imaging – A CT scan, ultrasound, or MRI of the urinary tract may be used to check for any structural abnormalities that could be prompting leukocytes.
  • Cystoscopy – A small camera on the end of a tube is inserted to directly visualize the urethra and bladder lining for signs of inflammation, tumors, etc.
  • Biomarker tests – Newer urine tests check for specialized molecules and antigens associated with certain cancers.

Follow-up urinalysis and urine cultures after treatment are important to confirm the leukocytes have resolved and that the infection or inflammation has been cured.

Treatments and Management of Leukocytes in Urine

The appropriate treatment depends on the underlying cause of the excess leukocytes found in the urine. Some general treatment options may include:

1. Medications

  • Antibiotics – Used to treat bacterial urinary tract infections, kidney infections, prostatitis, and some sexually transmitted diseases that can cause leukocytes in the urine.
  • Antifungals – Prescribed for fungal infections of the bladder, urinary tract, or reproductive organs that may lead to leukocyturia.
  • Alpha-blockers – Help relax the bladder and prostate muscles to improve urine flow; can help reduce recurrent UTIs and leukocytes.
  • Anti-inflammatories – Help reduce inflammation and pain associated with conditions like interstitial cystitis, bladder stones, or benign prostatic hyperplasia.
  • Immunosuppressants – These may be used to treat autoimmune and inflammatory disorders affecting the urinary system.

2. Procedures

  • Drainage and debridement – Inserting a catheter or needle to drain accumulated urine and pus from a blocked kidney, abscess, or cyst to help resolve the infection.
  • Surgery – Removal of kidney stones, tumors, diseased prostate tissue, etc. that may be causing recurrent leukocytes and urinary tract problems.
  • Bladder instillation – Instilling medications directly into the bladder that treat inflammation, pain, and irritation.

3. Lifestyle Approaches

  • Increased fluid intake – Drinking more water to dilute urine and avoid dehydration which can worsen urinary problems and leukocytes.
  • Urinary alkalinization – Making the urine less acidic to discourage bacterial growth; accomplished through diet or supplements.
  • Improved hygiene – Keeping the genital area clean; wiping front-to-back after using the toilet; avoiding potential irritants.
  • Pelvic floor therapy – Physical therapy to strengthen pelvic floor muscles and reduce inflammation and bladder pressure.
  • Stress management – Relaxation techniques, psychotherapy, or counseling for conditions worsened by stress.

Follow-up testing like urinalysis and urine culture should be conducted after treatment to confirm the leukocytes have resolved and the infection or inflammation has been cured. Further medical investigation may be needed for recurring or chronic cases not resolved with initial treatment.

What is the Typical Prognosis and Outlook for Leukocytes in Urine?

The prognosis for leukocyturia usually depends on the underlying cause:

  • Bacterial infections – Typically resolve completely with appropriate antibiotic treatment. However, some people may have recurrent UTIs requiring preventative care.
  • Interstitial cystitis – A chronic condition managed with medications and lifestyle changes, though gradual improvement is possible.
  • Kidney stones – Can recur over time, requiring repeat treatment and prevention strategies.
  • Cancers – Prognosis varies depending on cancer type and stage. Need consistent follow-up testing.
  • Injuries – Should heal with time after the initial irritation or trauma resolves.

With proper medical treatment guided by diagnostic testing, most causes of excess leukocytes in urine can be successfully cured or managed for improved quality of life. However, some chronic conditions like interstitial cystitis may require ongoing therapy.

If left untreated, leukocyturia may sometimes lead to complications like kidney infections, sepsis, kidney damage or failure. That’s why timely evaluation and follow-up testing is so important. Close monitoring and preventative care can help avoid recurrence and complications.

When Should You See a Doctor About Leukocytes in Urine?

It is advisable to see a doctor for evaluation if you have symptoms along with leukocytes in your urine. Even without symptoms, recurring or persistent leukocyturia on multiple urine tests warrants medical assessment to check for potential issues.

You should seek prompt medical care if symptoms like fever over 101°F, vomiting, chills, or shaking develop, as these can indicate a spreading kidney infection. Likewise, back pain accompanied by leukocytes can signal kidney inflammation.

Pregnant women should be evaluated for any leukocytes detected in urine, as they may represent a urinary tract infection that could lead to pregnancy complications if left untreated.

Seeking care is also important for at-risk groups like those over 65, diabetics, or immunocompromised patients in which even minor infections can become serious. Schedule an appointment with your doctor if unexplained leukocytes are found.


In summary, the presence of increased leukocytes in urine typically signifies inflammation or infection of part of the urinary tract. It should not be ignored, as it usually indicates some type of underlying medical condition needing further evaluation and appropriate treatment guided by a physician.

While in some cases leukocyturia may resolve on its own, persistent or recurring cases, especially with symptoms will require proper diagnosis and management. Catching the cause early provides the best chance for effective treatment and prevention of potential complications.

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