From the Guidelines
The presence of leukocytes and blood in a child's urinalysis (UA) is a strong indicator of a urinary tract infection (UTI) and necessitates prompt antibiotic treatment to prevent potential complications such as kidney damage or sepsis. According to the most recent and highest quality study 1, the sensitivity and specificity of leukocyte esterase and nitrites in urine dipstick tests vary, but the presence of leukocytes or blood in the urine is a significant finding that warrants further investigation and treatment.
Key Findings
- The study found that leukocyte esterase had a higher sensitivity (84%) compared to nitrites (34.2% to 44.6%) in detecting UTIs in children under 2 years of age 1.
- The presence of leukocytes in urine, indicated by a white blood cell count greater than 20/hpf, had a high likelihood ratio (LR=19) for UTI, while the presence of blood (hematuria) can result from infection-related irritation of the urinary tract lining 1.
- A negative urinalysis result can help rule out UTI, but a positive result should prompt a urine culture obtained by catheterization or suprapubic aspiration to confirm the diagnosis 1.
Treatment and Management
- First-line treatment for UTI typically includes amoxicillin-clavulanate (40 mg/kg/day divided twice daily) or cephalexin (50-100 mg/kg/day divided three to four times daily) for 7-10 days 1.
- For febrile UTIs or pyelonephritis, consider ceftriaxone (50-75 mg/kg/day) initially, and ensure adequate hydration and fever control with acetaminophen (15 mg/kg every 4-6 hours) or ibuprofen (10 mg/kg every 6-8 hours) if the child is febrile.
- A follow-up urinalysis after treatment completion is recommended to confirm resolution, and further evaluation with renal ultrasound or voiding cystourethrogram may be necessary to identify anatomical abnormalities like vesicoureteral reflux in cases of recurrent UTIs.
From the Research
Significance of Leukocytes and Hematuria in Urinalysis
- The presence of leukocytes in the urine is of increasing diagnostic importance in urinary tract infections (UTIs) 2.
- A study found that pyuria, presence of bacteria, leukocyte esterase, and nitrite positivity in urinalysis should be considered together, and simultaneous urine culture test should be performed in the diagnostic evaluation of UTI 3.
- The absence of pyuria in urinalysis cannot exclude UTI in patients with suggestive clinical findings, and urine culture tests should be performed in children with suspected UTI even in the absence of pyuria 3.
Relationship between Urinalysis Findings and Responsible Pathogens
- A study found that E. coli more commonly caused leukocyturia, leukocyte esterase positivity, and pyuria, while pyuria might be lacking in UTIs associated with Klebsiella spp. and Enterococcus spp. 3.
- Another study found that positive leukocytes esterase had an LR of 2.5, positive nitrites had an LR of 2.8, and urine white blood cell count had an LR of 1.8 in predicting E. coli versus non-E. coli infections 4.
Diagnostic Importance of Urinalysis
- Urinalysis is not an accurate predictor of UTI, but a positive urine culture in the presence of negative UA most likely grew non-E. coli organisms, whereas most UA(+) results were associated with E. coli 4.
- A systematic review found that dipstick positive for both leukocyte esterase and nitrite or microscopy positive for both pyuria and bacteriuria can be used to rule in UTI, while dipstick negative for both LE and nitrite or microscopic analysis negative for both pyuria and bacteriuria can be used to rule out UTI 5.
Novel Biomarkers of UTI
- Several promising serum and urine biomarkers of UTI have been identified, including leukocyte esterase, C-reactive protein, procalcitonin, interleukins, and others 6.
- These biomarkers may help improve the diagnosis and management of UTIs, particularly in cases where clinical symptoms are uncharacteristic or asymptomatic 6.