How to manage a patient with leukocytosis (elevated White Blood Cell (WBC) count) and neutrophilia (elevated neutrophil count) on Complete Blood Count (CBC) and pyuria (elevated WBC) on urinalysis?

Management of Leukocytosis with Neutrophilia and Pyuria

The presence of pyuria on urinalysis combined with leukocytosis and neutrophilia on CBC requires immediate assessment for urinary symptoms—if specific urinary symptoms (dysuria, frequency, urgency, fever, or gross hematuria) are present, obtain a properly collected urine culture before initiating antibiotics; if the patient is asymptomatic, do not treat, as this represents asymptomatic bacteriuria. 1

Immediate Diagnostic Steps

1. Assess for Specific Urinary Symptoms

• Determine if the patient has acute onset of UTI-associated symptoms: dysuria, urinary frequency, urgency, fever >38.3°C, or gross hematuria 1
• Non-specific symptoms like confusion, functional decline, or falls alone in older adults should NOT trigger UTI evaluation or treatment without specific urinary symptoms 1
• The presence of leukocytes combined with these symptoms strongly suggests UTI, with specificity increasing to 96% when accompanied by positive nitrite 1

2. Evaluate Specimen Quality

• Check for epithelial cell contamination on urinalysis—high epithelial cell counts indicate contamination and are a common cause of false-positive leukocyte esterase results 1
• If contamination is suspected with strong clinical suspicion for UTI, obtain a properly collected specimen:
  • Women: perform in-and-out catheterization for uncontaminated specimen 1
  • Men: use midstream clean-catch or freshly applied clean condom catheter 1

3. Obtain Urine Culture Before Antibiotics

• If symptomatic with pyuria (≥10 WBCs/HPF or positive leukocyte esterase), collect urine culture with antimicrobial susceptibility testing before starting antibiotics 1
• Do not delay culture collection—always obtain culture before antibiotics in cases with significant pyuria 1
• Process specimen within 1 hour at room temperature or 4 hours if refrigerated 1

Interpretation of CBC Findings

Assess for Left Shift and Absolute Band Count

• Manual differential count is essential for accurately assessing band forms and immature neutrophils—do not rely on automated analyzer flags alone 2
• An absolute band count ≥1,500 cells/mm³ has the highest likelihood ratio (14.5) for documented bacterial infection 2, 3
• A left shift (≥16% band neutrophils) has a likelihood ratio of 4.7 for bacterial infection, even with normal total WBC count 2, 3

Evaluate Neutrophil Percentage

• Neutrophil percentage >90% has a likelihood ratio of 7.5 for bacterial infection 3
• A neutrophil percentage of 84% is moderately elevated and warrants clinical evaluation, though it does not reach the highest-risk threshold 3
• Decreased lymphocyte percentage is consistent with acute bacterial process rather than viral etiology 3

Management Algorithm Based on Symptom Status

If Patient is SYMPTOMATIC (has specific urinary symptoms):

1. Obtain urine culture before antibiotics 1
2. Initiate empiric antibiotics based on suspected infection source and local resistance patterns after obtaining culture 2
3. For suspected pyelonephritis or urosepsis (fever, hypotension, rigors), proceed with culture despite any laboratory findings 1
4. Consider blood cultures if bacteremia is highly suspected clinically 2

If Patient is ASYMPTOMATIC:

• Do NOT order urinalysis or culture 1
• Do NOT treat with antibiotics—asymptomatic bacteriuria with pyuria should not be treated, even with positive culture (Grade A-II recommendation from IDSA) 1
• Asymptomatic bacteriuria is common, with prevalence of 15-50% in non-catheterized long-term care facility residents 1
• Pyuria accompanying asymptomatic bacteriuria provides no clinical benefit when treated and leads to unnecessary antibiotic exposure and resistance development 1

Additional Diagnostic Considerations

Evaluate for Alternative Infection Sources

• Respiratory tract: If respiratory symptoms present, consider pulse oximetry and chest radiography 2
• Skin/soft tissue: If skin findings present, consider needle aspiration or deep-tissue biopsy for unusual pathogens 2
• Gastrointestinal: If GI symptoms present, evaluate volume status and consider stool studies including C. difficile 2
• Intra-abdominal: In patients with cirrhosis and ascites, perform diagnostic paracentesis to rule out spontaneous bacterial peritonitis (neutrophil count >250 cells/mm³ in ascitic fluid indicates SBP) 3

Consider Non-Infectious Causes of Neutrophilia

• Medications: lithium, beta-agonists, epinephrine can cause neutrophilia with left shift 2, 3
• Physiologic stress: surgery, exercise, trauma, emotional stress can double peripheral WBC count within hours 4
• Other conditions: asplenia, smoking, obesity, chronic inflammatory conditions 4

Critical Pitfalls to Avoid

• Do NOT treat pyuria alone without symptoms—this is the most common error leading to antibiotic overuse 1
• Do NOT interpret cloudy or smelly urine as infection in elderly patients without specific urinary symptoms 1
• Do NOT ignore left shift when total WBC is normal—this combination still indicates significant bacterial infection requiring evaluation 2
• Do NOT rely solely on automated differential—manual count is essential for accurate band assessment 2
• Do NOT treat based on laboratory findings alone—correlate with clinical presentation and specific infection symptoms 2

Special Population Considerations

Older Adults and Long-Term Care Residents

• Left shift has particular diagnostic importance due to decreased basal body temperature and frequent absence of typical infection symptoms 2
• Evaluation is indicated only with acute onset of specific UTI-associated symptoms 1
• Prevalence of asymptomatic bacteriuria is 15-50% in this population—do not screen or treat 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
• Negative leukocyte esterase effectively excludes symptomatic UTI 1

Hemodialysis Patients

• Hyperleukocyturia (>10 WBC/HPF) occurs in 46.7% of asymptomatic HD patients 5
• Urinary WBC increases with decreased urinary volume—diagnostic criteria for pyuria in patients with normal renal function may not apply 5