Management of Mild Leukocytosis with Neutrophilia (WBC 11.4, Neutrophils 6.74)
These values represent mild elevation that requires clinical correlation but does not mandate immediate intervention in an asymptomatic patient. 1, 2
Immediate Assessment Priority
Your first step is to determine if this patient has any signs of infection or sepsis, as this fundamentally changes management:
- Check vital signs immediately for fever (>38°C or <36°C), hypotension (<90 mmHg systolic), tachycardia, tachypnea, or altered mental status 1, 3
- Obtain lactate level urgently if any systemic signs are present—a level >3 mmol/L confirms severe sepsis and mandates immediate broad-spectrum antibiotics within 1 hour 1, 3
- Monitor urine output as oliguria (<30 ml/h) indicates sepsis-related organ dysfunction 1, 3
Critical Diagnostic Step: Manual Differential
You must obtain a manual differential count immediately—automated analyzers are insufficient and will miss critical findings. 1, 3, 2
- An absolute band count ≥1,500 cells/mm³ has the highest likelihood ratio (14.5) for documented bacterial infection 2, 4
- A left shift ≥16% bands has a likelihood ratio of 4.7 for bacterial infection, even with normal total WBC 1, 2, 4
- Look for toxic granulations, Döhle bodies, and cytoplasmic vacuoles, which have 80% sensitivity for infectious/inflammatory disease 1, 4
Clinical Context Determines Next Steps
If Patient is Symptomatic or Has Elevated Bands:
- Obtain blood cultures before antibiotics if any systemic signs are present 1
- Obtain chest radiograph to evaluate for pneumonia, as leukocytosis is associated with increased mortality in pneumonia 2
- Perform urinalysis ONLY if urinary symptoms are present—do NOT test asymptomatic patients, as asymptomatic bacteriuria should not be treated 3, 2
- Initiate targeted antimicrobial therapy based on identified source and local resistance patterns 2
If Patient is Completely Asymptomatic with Normal Bands:
Do NOT initiate antibiotics based solely on this mild WBC elevation. 2
- Repeat CBC with manual differential in 12-24 hours to track trajectory 2
- Review medication list for corticosteroids, as chronic steroid use increases WBC by average of 5×10⁹/L 5
- Assess for recent COVID-19 infection, as persistent neutrophilia and lymphopenia can occur for months post-infection 6
Important Caveats
- The absence of fever does NOT exclude bacterial infection, particularly in older adults where typical symptoms are frequently absent 2
- Do not dismiss elevated neutrophils simply because total WBC is only mildly elevated—left shift with normal WBC still indicates serious bacterial infection 1
- Basophilia is highly specific for chronic myeloid leukemia (CML) when present with leukocytosis—if present, obtain BCR-ABL1 fusion gene testing 1
- Extreme leukocytosis (>30,000-50,000/mm³) without infection should prompt consideration of leukocyte adhesion defect (LAD) or paraneoplastic syndrome from solid tumors 1, 7, 8