From the Guidelines
The presence of WBC esterase in a 5-year-old female's urinalysis is highly suggestive of a urinary tract infection (UTI), and I strongly recommend empiric treatment with an oral antibiotic such as cefixime 8 mg/kg once daily or amoxicillin-clavulanate 45 mg/kg/day divided twice daily for 7-10 days while awaiting urine culture results. According to a Class II meta-analysis of diagnostic tests for urinary tract infection, which evaluated 95 studies in 95,703 children aged 18 years or younger, the sensitivity and specificity of leukocyte esterase or nitrite were 88% (95% CI 82% to 91%) and 79% (95% CI 69% to 87%), respectively 1. This suggests that WBC esterase is a reliable marker for UTI in children.
Key Considerations
- Ensure adequate hydration and follow-up with a repeat urinalysis after completing the antibiotic course.
- Parents should be advised to encourage the child to urinate frequently, practice proper front-to-back wiping, avoid bubble baths, and wear cotton underwear.
- If the child has fever, flank pain, or appears toxic, immediate medical evaluation is necessary as this could indicate pyelonephritis requiring more aggressive treatment.
Diagnostic Approach
- A Class III retrospective review of 375 pediatric ED patients aged 0 to 10 years found that urine dipstick sensitivity was 92.5% (95% CI 84.3% to 100%) and specificity was 39.4% (95% CI) 1.
- However, a positive urinalysis result should prompt a urine culture obtained by catheterization or suprapubic aspiration to confirm the diagnosis, as a positive bagged urinalysis result may be a false positive 1.
Treatment and Prevention
- WBC esterase is an enzyme released by white blood cells and serves as a marker for pyuria (white blood cells in urine), which typically indicates an inflammatory response to bacterial infection in the urinary tract.
- In young females, UTIs are relatively common due to their shorter urethra and anatomical proximity to the rectum, which facilitates bacterial entry into the urinary system.
- A study by Waseem et al found that 30% of children with a positive urine culture result had a negative urinalysis result, highlighting the importance of urine culture in confirming the diagnosis 1.
From the Research
WBC Esterase in a 5-Year-Old Female
- The provided studies do not directly address the topic of WBC esterase in a 5-year-old female.
- However, some studies discuss the use of white blood cell (WBC) counts in diagnosing infections in children 2, 3, 4.
- A study from 1991 found that WBC counts greater than or equal to 35,000/microliters in children presenting to a pediatric emergency department may be considered extreme leukocytosis 2.
- Another study from 2019 found that eosinopenia, a parameter of the WBC count, can be a valuable tool for diagnosing bacterial infections in the emergency department 3.
- A 2014 study evaluated the accuracy of total white blood cell and absolute neutrophil counts for detecting serious bacterial infections in febrile children under 5 years of age, but found that these counts are not sufficiently accurate triage tests 4.
- There is no direct information available on WBC esterase in the provided studies, and the available information on WBC counts may not be directly applicable to the specific context of WBC esterase in a 5-year-old female 5, 6.