Urine Leukocyte Esterase (U-LEU)

What is Urine Leukocyte Esterase?

Leukocyte esterase is an enzyme produced by white blood cells (neutrophils). This test detects the presence of white blood cells in urine, which typically indicates infection or inflammation somewhere in the urinary tract.

Why is it Tested?

Healthcare providers use this test to screen for urinary tract infections (UTIs), evaluate symptoms like painful urination or frequent urges, and monitor patients with recurrent UTIs. It’s often performed alongside nitrite testing for comprehensive UTI screening.

Normal Ranges

Results are typically reported as:

Negative: No detectable leukocyte esterase (normal result)
Trace/1+: Minimal white blood cell activity
2+ to 4+: Increasing levels of white blood cell presence

A negative result is normal. Any positive result suggests white blood cell activity in the urinary tract.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Positive Results (Any Level)

Positive leukocyte esterase suggests:

Urinary tract infection (UTI)
Bladder infection (cystitis)
Kidney infection (pyelonephritis)
Urethral inflammation
Contamination from vaginal secretions

Strongly Positive Results (3-4+)

High levels often indicate:

Significant bacterial infection
Severe UTI requiring prompt treatment
Possible kidney involvement
Need for antibiotic therapy
Risk of complications if untreated

How to Track Over Time

Monitoring leukocyte esterase helps track UTI treatment effectiveness and detect recurrent infections. Persistently positive results after treatment may indicate antibiotic resistance, incomplete treatment, or underlying urological problems requiring further investigation.

Urine Leukocyte Esterase