What is the appropriate management for a patient with leukocytosis and neutrophilia, along with slightly elevated RDW and high MPV?

Management of Leukocytosis with Neutrophilia

This patient requires immediate evaluation for bacterial infection, as the combination of leukocytosis (WBC 14.1 k/mm³) with absolute neutrophilia (9.7 k/uL) and elevated immature granulocytes (1.6%) strongly suggests an active infectious process that warrants prompt diagnostic workup and empirical antimicrobial therapy if clinically indicated. 1

Immediate Clinical Assessment

The presence of leukocytosis (WBC ≥14,000 cells/mm³) combined with left shift (immature granulocytes 1.6%, absolute count 0.2 k/uL) carries a high probability of underlying bacterial infection, with a likelihood ratio of 3.7 for leukocytosis alone and significantly higher when combined with left shift. 1 The elevated absolute neutrophil count of 9.7 k/uL (reference range 1.5-7.8 k/uL) and absolute monocyte count of 1.1 k/uL (reference 0.2-1.0 k/uL) further support an inflammatory or infectious etiology. 1

Key Clinical Indicators to Assess:

• Fever or hypothermia: Temperature >38°C or <36°C 1
• Hemodynamic stability: Blood pressure, heart rate, signs of sepsis 1
• Localizing symptoms: Respiratory (cough, dyspnea), urinary (dysuria, frequency), gastrointestinal (diarrhea, abdominal pain), or skin/soft tissue findings 1
• Recent procedures or hospitalizations: Particularly relevant for healthcare-associated infections 1

Diagnostic Workup Priority

Essential Initial Tests:

• Blood cultures (before antibiotics if sepsis suspected): Mandatory for patients with fever and leukocytosis to identify bacteremia 1
• Urinalysis with microscopy and culture: Only if acute urinary symptoms present (dysuria, frequency, gross hematuria, new incontinence) - not for asymptomatic patients 1
• Chest imaging: If respiratory symptoms or signs of pneumonia 1
• Site-specific cultures: Based on clinical localization (wound, sputum if productive, stool if diarrhea present) 1

The slightly elevated RDW-SD (54.7 fL) and MPV (12.4 fL) are non-specific findings that may reflect inflammatory states but do not alter immediate management priorities. 2, 3

Management Algorithm

If Febrile with Leukocytosis:

Empirical broad-spectrum antimicrobial therapy is mandatory within 1 hour if signs of sepsis or severe infection are present. 1 The choice of antibiotics should cover common bacterial pathogens based on the suspected source:

• Respiratory source: Cover typical and atypical organisms
• Urinary source: Gram-negative coverage (fluoroquinolone or third-generation cephalosporin) 1
• Intra-abdominal source: Broad-spectrum with anaerobic coverage 1
• Unknown source with sepsis: Vancomycin plus anti-pseudomonal beta-lactam 1

If Afebrile with Leukocytosis:

The absence of fever does not exclude bacterial infection in certain populations (elderly, immunocompromised). 1 However, in the absence of fever, leukocytosis/left shift, or specific focal infection manifestations, additional diagnostic tests may have low yield. 1

Proceed with targeted workup based on:

• Presence of localizing symptoms or signs
• Patient risk factors (age >65, immunosuppression, recent surgery)
• Clinical stability

Special Considerations:

The monocyte predominance (7.7%) may suggest intracellular pathogens such as Salmonella if gastrointestinal symptoms are present. 1 The elevated absolute monocyte count warrants consideration of chronic inflammatory conditions if infection is excluded. 1

Monitoring and Follow-up

• Daily CBC with differential until WBC normalizes and clinical improvement documented 1
• Reassess at 48-72 hours: If fever persists despite appropriate antibiotics, consider:
  • Resistant organisms or inadequate source control
  • Non-bacterial etiology (viral, fungal, non-infectious inflammation)
  • Imaging for occult abscess or complications 1

Duration of Antimicrobial Therapy:

Antibiotics can be discontinued when: 1

• Patient afebrile for 48 hours
• Clinical symptoms resolved
• Blood cultures negative
• Source control achieved

Critical Pitfalls to Avoid

• Do not assume infection equals fever: Leukocytosis with left shift has high predictive value for bacterial infection even without fever, particularly in elderly or immunocompromised patients 1
• Do not obtain urine cultures in asymptomatic patients: Asymptomatic bacteriuria is common (15-50% in long-term care) and does not require treatment 1
• Do not delay antibiotics for culture results if sepsis suspected: Blood cultures should be obtained rapidly, but empirical therapy must not be delayed 1
• Do not attribute leukocytosis solely to stress or inflammation without excluding infection: The combination of elevated WBC, neutrophilia, and left shift has a likelihood ratio of 14.5 for bacterial infection when band count ≥1500 cells/mm³ 1

The elevated platelet count (265 k/mm³) is within normal range and commonly seen with bacterial infections as an acute phase reactant. 1