Elevated Leukocyte Esterase in Urine: Causes with Treatment

Leukocyte esterase is an enzyme that is produced by white blood cells known as leukocytes. It plays an important role in the human immune system response. When an infection or inflammation occurs, leukocytes will release leukocyte esterase into the bloodstream and other areas of the body.

The main role of leukocyte esterase is to help leukocytes carry out their function. Leukocytes, which include neutrophils, lymphocytes, monocytes, eosinophils, and basophils. They are responsible for protecting the body from infection and disease. Leukocyte esterase assists with destroying the structural integrity of bacterial and other pathogen cell walls. This leads to their eventual death and aids the body in fighting infection.

One place where leukocyte esterase usually ends up is in the urine. This enzyme’s presence serves as a useful biomarker that can signal urinary tract issues. When the level of leukocyte esterase is higher than normal in a urine sample, it often indicates an underlying condition that has triggered the immune system.

Symptoms of High Leukocyte Esterase

When leukocyte esterase is elevated due to an infection or inflammatory condition, certain signs and symptoms often arise. Being aware of these common symptoms can help prompt people to seek medical evaluation and proper treatment:

• Pain or Burning During Urination: Also called dysuria, this is pain or a stinging sensation when trying to urinate. It is one of the hallmark symptoms of a UTI, usually stemming from inflammation in the urethra and bladder. The urine itself can irritate the inflamed tissues when it passes through.
• Increased Urinary Frequency and Urgency: People with a UTI often feel like they need to urinate more frequently, yet when they try, only small amounts come out. There is a constant urge (urgency) to urinate due to inflammation sending signals to the brain through the nervous system.
• Cloudy, foul-smelling, or Bloody Urine: Changes in urine appearance can indicate infection or inflammation. Cloudy urine suggests excess bacteria, white blood cells, or debris. Bad-smelling urine may be caused by concentrated bacteria increasing ammonia levels. Blood in the urine (hematuria) could stem from bleeding in the kidneys or urethra.
• Pelvic Pain or Pain in Lower Back: Pelvic pain or achiness indicates inflammation around the bladder, ureters, uterus, or prostate. Lower back pain, especially on one side, can mean a kidney infection is present. This flank pain occurs as swelling causes kidney distension.
• Fever, Chills, and Malaise: Systemic signs of infection like fever, sweats, chills, muscle aches, nausea, and fatigue are common if the infection spreads to the kidney or bloodstream. This is more likely with pyelonephritis or urosepsis.
• Incontinence or Leakage of Urine: Some people lose control over their bladder as a UTI symptom, leading to accidental leakage of small amounts of urine (incontinence). The inflammation makes it harder for the bladder to fully empty and hold urine normally.

What Causes Leukocyte Esterase Levels to Rise?

There are several possible underlying causes for increased levels of leukocyte esterase showing up in urinalysis results:

1. Urinary Tract Infections

The most common reason for elevated leukocyte esterase is due to urinary tract infections, shortened as UTIs. These infections occur when bacteria, most often from the digestive tract, get into the urinary system and begin to multiply.

Common UTI-causing pathogens include Escherichia coli (E. coli), Klebsiella species, Proteus species, and Enterococcus species. The immune system responds by sending leukocytes to the site of infection, where they release leukocyte esterase as part of the process of breaking down the bacteria.

2. Kidney Infections

Also referred to as pyelonephritis, kidney infections develop when bacteria travel from the bladder up to the kidneys themselves. Here they provoke a significant immune response as the body fights the infection, including increased leukocytes with elevated leukocyte esterase levels. Kidney infections are considered a complication of untreated lower urinary tract infections.

3. Bladder Infections

Bladder infections, medically termed cystitis, occur when bacteria infect the bladder but do not spread to other parts of the urinary tract.

This localized infection triggers inflammation as the bladder’s mucosal lining becomes irritated and swollen. White blood cells rush to the area, releasing leukocyte esterase as they attempt to rid the bladder of pathogens.

4. Prostatitis

In men, the prostate gland can become inflamed and infected, known as acute or chronic prostatitis. This frequently shows up as having higher leukocyte esterase readings on a urinalysis. The immune system responds to the infected prostate tissue by activating leukocytes.

5. Kidney Stones

Kidney stones are crystallized mineral deposits that form in the kidneys. They can cause damage and bleeding and often become infected. White blood cells will be sent to deal with the kidney stone, releasing leukocyte esterase as they are activated. Very painful kidney stone episodes can be associated with increased leukocyte esterase.

6. Interstitial Cystitis

This chronic bladder condition is believed to be caused by a defect in the bladder lining’s protective mucous coating. This allows toxic substances in the urine to irritate the bladder walls, causing scar tissue, inflammation, and ulcerations. Chronic inflammation can cause an elevated amount of leukocyte esterase even without active infection.

7. Chemical Irritation

Exposure to certain chemicals, toxins, or radiation therapy can cause inflammation and irritation of the bladder, ureters, or urethra. Examples include chemotherapy medications, products like spermicides or feminine hygiene sprays, and urinary catheters. The inflammation triggers increased leukocytes and leukocyte esterase.

8. Urinary Tract Tumors

Both cancerous and non-cancerous urinary tract tumors can provoke inflammation, irritation, and bleeding. As the body reacts, more leukocyte esterase will be released as leukocytes are recruited to the site of the tumor.

9. Other Diseases

Certain diseases that directly affect white blood cell counts in the body can result in increased leukocyte esterase in the urine. These include leukemia, which causes abnormal overproduction of white blood cells, and kidney failure, which allows leukocyte esterase to leak into the urine rather than being reabsorbed.

How Doctors Diagnose High Leukocyte Esterase

When elevated leukocyte esterase is detected on a urine dipstick or basic urinalysis, doctors can use other tests to confirm infection or inflammation and pinpoint the underlying cause:

• Microscopic Urinalysis: A trained technician will examine a urine sample under a microscope, looking for increased leukocytes, bacteria, and other abnormalities. An unusually high amount of leukocytes strongly suggests a UTI or inflammatory condition is present.
• Urine Culture: This test grows a urine sample in a special medium overnight to identify the specific type of bacteria present and determine which antibiotic would work best. A urine culture is needed to officially diagnose a UTI, rather than just suspected inflammation.
• Cystoscopy: A small, flexible camera is threaded through the urethra to the bladder, allowing doctors to visually inspect the urethra and bladder wall. Inflammation, tumors, stones, and other issues can be detected.
• Imaging Studies: Ultrasounds, CT scans, or MRIs can provide detailed views of the urinary tract. Doctors look for any obstructural abnormalities, tumors, kidney stones, or damage that could be provoking increased leukocyte esterase.
• Complete Blood Count: This common blood test determines if an infection has caused an elevated white blood cell count. With serious kidney infections, neutrophilia (high neutrophils) and leukocytosis (high white blood cells overall) are expected.
• Blood Cultures: If bacteria have spread to the bloodstream, causing urosepsis, blood cultures can isolate the pathogens. Positive blood cultures confirm a severe infection is present.
• Urinary Tract Endoscopy: Cystoscopy was described before, but other endoscopic procedures include ureteroscopy to examine the ureters and nephroscopy to view inside the kidneys. Endoscopy often includes biopsies of abnormal tissue.
• Antibody Testing: Some specific UTIs like chlamydia and mycoplasma can be confirmed through antibody tests detecting the body’s immune reaction. Helpful when the bacteria are difficult to culture.