What does a urinalysis showing moderate high leukocyte (white blood cell) esterase with 4-6 White Blood Cells (WBCs) and 0-3 epithelial cells indicate?

Interpreting a Urinalysis with Moderate-High Leukocyte Esterase, 4-6 WBCs, and 0-3 Epithelial Cells

A urinalysis showing moderate-high leukocyte esterase with 4-6 WBCs and 0-3 epithelial cells strongly suggests a urinary tract infection (UTI) that requires further confirmation with urine culture before initiating treatment. 1

Understanding the Significance of These Findings

Leukocyte Esterase

• Moderate-high leukocyte esterase indicates significant pyuria (presence of white blood cells in urine)
• Sensitivity: 83% (range 67-94%)
• Specificity: 78% (range 64-92%) 1
• Positive leukocyte esterase has a likelihood ratio of 2.5 for predicting E. coli infection 2

White Blood Cells (WBCs)

• 4-6 WBCs per high-power field represents pyuria
• According to guidelines, >5 WBCs/hpf is considered positive for pyuria 1
• This level of WBCs has a moderate likelihood ratio (LR=1-2.8) for predicting UTI 1

Epithelial Cells

• 0-3 epithelial cells is a low count, suggesting minimal contamination
• Higher epithelial cell counts would indicate potential contamination of the specimen

Diagnostic Algorithm

1. Assess the collection method:

   • Clean-catch midstream specimens are preferred for accuracy
   • Bag specimens have higher contamination rates (relative risk 2.7 times higher than catheterization) 1

2. Evaluate for clinical symptoms:

   • In symptomatic patients (dysuria, frequency, urgency), these findings strongly suggest UTI
   • In asymptomatic patients, consider asymptomatic bacteriuria (especially important in pregnancy) 1

3. Confirm with urine culture:

   • A urine culture is necessary to confirm UTI diagnosis 1
   • Culture should be obtained before starting antibiotics
   • Positive culture defined as ≥50,000 CFU/mL of a single uropathogen 1

Important Considerations

Age-Specific Interpretation

• In children under 2 years with fever: These findings warrant urine culture and empiric treatment 1
• In adults: These findings plus symptoms are sufficient to start empiric treatment while awaiting culture 1
• In elderly patients: Moderate-high leukocyte esterase with pyuria plus symptoms warrants treatment unless nitrite is negative 1

Potential Pitfalls

1. False positives:

   • Up to 50% of asymptomatic women may have abnormal urinalysis results including leukocyte esterase >trace and WBCs >5/HPF 3
   • Only nitrite shows high specificity (98%) 1, 3

2. False negatives:

   • Pyuria is absent in approximately 20% of febrile infants with culture-confirmed pyelonephritis 1
   • Negative leukocyte esterase and nitrite do not completely rule out UTI 1

3. Specimen quality matters:

   • Even with ideal collection technique, contamination rates can be high (63%) 3
   • Low epithelial cell count (0-3) suggests good specimen quality

Recommended Next Steps

1. Obtain urine culture before starting antibiotics if not already done 1

2. Consider empiric treatment while awaiting culture results if patient is symptomatic 1

   • For positive leukocyte esterase with pyuria, consider antibiotics targeting E. coli (cephalosporins show good sensitivity) 2

3. If treating empirically, choose antibiotics based on:

   • Local resistance patterns
   • Patient age and comorbidities
   • Pregnancy status
   • Previous UTI history and antibiotic exposure

4. Follow up to ensure resolution of symptoms and, if indicated, repeat urinalysis to document clearance

Remember that while these findings strongly suggest UTI, the gold standard for diagnosis remains a positive urine culture with clinical symptoms. The moderate-high leukocyte esterase with 4-6 WBCs is highly suggestive but not definitive without culture confirmation.