What does it mean to have 2+ esterase in urine?

What Does 2+ Esterase in Urine Mean?

2+ leukocyte esterase in urine indicates the presence of white blood cells (pyuria), but this finding alone does NOT diagnose a urinary tract infection and requires clinical correlation with symptoms before any treatment decision is made. 1

Understanding the Test Result

The leukocyte esterase dipstick test detects an enzyme released by white blood cells in urine, with results reported as negative, trace, 1+, 2+, or 3+ based on color intensity. 1 A 2+ result represents a moderate level of leukocyte esterase activity, correlating with pyuria (≥10 WBCs per high-power field on microscopy). 2, 1

Diagnostic Performance

• Sensitivity: 83% (range 67-94%) for detecting UTI 1
• Specificity: 78% (range 64-92%) when used alone 1
• Combined with nitrite: Sensitivity increases to 93% with specificity of 96% 1, 3
• Negative predictive value: Excellent (82-91%) when both leukocyte esterase and nitrite are negative 1

Clinical Significance: Symptoms Are Essential

The critical distinction is whether urinary symptoms are present. 1, 3

If Symptomatic (dysuria, frequency, urgency, fever, gross hematuria):

• Obtain urine culture before starting antibiotics 1, 3
• The combination of 2+ leukocyte esterase with symptoms strongly suggests UTI 1
• If nitrite is also positive, specificity reaches 96%, justifying empiric treatment while awaiting culture 3
• Start empiric antibiotics immediately after obtaining culture if symptomatic 3

If Asymptomatic:

• Do NOT treat—this represents asymptomatic bacteriuria 1, 3
• Asymptomatic bacteriuria with pyuria is extremely common (15-50% prevalence in long-term care residents) 1
• Treatment provides no clinical benefit and promotes antibiotic resistance 1, 3
• Do not pursue further testing or treatment 1

Common Causes of False-Positive Results

Contamination is the most frequent cause of misleading results. 1

• Vaginal contamination in women: Particularly prepubertal girls with vulvovaginitis 4
• Phimosis in boys: Significantly associated with false-positive leukocyte esterase 4
• Poor specimen collection: High epithelial cell counts indicate contamination 2
• Non-infectious inflammation: Genitourinary inflammation from many noninfectious causes produces pyuria 1

Proper Specimen Collection

• Women: Midstream clean-catch or in-and-out catheterization if unable to provide clean specimen 1
• Men: Midstream clean-catch or clean condom catheter 1
• Children: Catheterization or suprapubic aspiration (bag specimens have 85% false-positive rate) 3
• Process within 1 hour at room temperature or 4 hours if refrigerated 1

Critical Pitfalls to Avoid

Never treat based on urinalysis alone without symptoms. 1, 3 The positive predictive value of pyuria for infection is exceedingly low because it indicates inflammation, not necessarily infection. 1

Do not assume cloudy or smelly urine equals infection, especially in elderly patients—these observations alone do not indicate symptomatic infection. 1

In elderly patients with confusion or delirium alone: Do not order urinalysis or treat for UTI without specific urinary symptoms (dysuria, frequency, urgency, fever, gross hematuria). 1

Bagged urine specimens in children: Always confirm positive results with catheterized specimen before treating due to 85% false-positive rate. 3

When to Obtain Urine Culture

Culture is mandatory in these situations: 1, 3

• Any symptomatic patient before starting antibiotics 1, 3
• Febrile infants <2 years (10-50% of culture-proven UTIs have false-negative urinalysis) 3
• Suspected pyelonephritis or urosepsis 1
• Recurrent UTIs (to guide targeted therapy) 1
• Pregnant women (even if asymptomatic) 1

Do NOT obtain culture if: 1

• Patient is asymptomatic without specific urinary symptoms 1
• Elderly patient with only non-specific symptoms (confusion, falls) 1
• Catheterized patient without fever or hemodynamic instability 1

Special Population Considerations

Pediatric Patients

• Positive leukocyte esterase should prompt urine culture collection before initiating antimicrobial therapy in febrile infants and young children 1
• Lower sensitivity in infants who void frequently due to shorter bladder dwell time 2, 3
• Prepubertal girls with false-positive results often have vulvovaginitis—detailed history and physical examination can avoid unnecessary testing 4

Elderly and Long-Term Care Residents

• Evaluate only with acute onset of specific UTI-associated symptoms 1
• Absence of pyuria can exclude bacteriuria 1
• Presence of pyuria has low predictive value due to high prevalence of asymptomatic bacteriuria 1

Catheterized Patients

• Do not screen for or treat asymptomatic bacteriuria 1
• Reserve testing for symptomatic patients with fever, hypotension, or specific urinary symptoms 1