What does it mean when an individual, particularly an elderly patient with a history of respiratory or inflammatory disease, presents with elevated neutrophils (neutrophilia)?

What Elevated Neutrophils Mean

Elevated neutrophils (neutrophilia) most commonly indicates an underlying bacterial infection requiring immediate diagnostic evaluation, particularly when accompanied by a left shift (increased band forms), which has a likelihood ratio of 14.5 for documented bacterial infection when absolute band count ≥1,500 cells/mm³. 1, 2

Immediate Diagnostic Priorities

Obtain a manual differential count immediately—automated analyzers are insufficient for detecting left shift and band forms, which are critical for determining infection severity. 1, 2, 3

Key Thresholds to Assess

• Absolute band count ≥1,500 cells/mm³: Highest diagnostic accuracy (likelihood ratio 14.5) for bacterial infection, even without fever 1, 2, 3
• Band percentage ≥16%: Significant left shift with likelihood ratio 4.7 for bacterial infection 1, 2, 3
• Total WBC ≥14,000 cells/mm³: Likelihood ratio only 3.7 for infection—less predictive than left shift alone 2, 3

Critical caveat: Left shift can occur with normal total WBC count and still indicates serious bacterial infection requiring full evaluation. 1, 2, 3

Clinical Evaluation Algorithm

Step 1: Assess for Infection Sources

• Respiratory: Cough, dyspnea, chest pain, hypoxemia—obtain pulse oximetry and chest radiography if hypoxemia documented 1, 3
• Urinary: Dysuria, flank pain, frequency—perform urinalysis for leukocyte esterase/nitrite and microscopic WBCs; obtain urine culture if pyuria present 1, 3
• Skin/soft tissue: Erythema, warmth, purulent drainage—consider needle aspiration or deep-tissue biopsy if fluctuant areas present or unusual pathogens suspected 1
• Gastrointestinal: Peritoneal signs, diarrhea—evaluate for C. difficile if colitis symptoms present 1

Step 2: Assess for Systemic Infection/Sepsis

• Fever >38°C or hypothermia <36°C 2, 3
• Hypotension <90 mmHg systolic 2, 3
• Tachycardia, tachypnea 2, 3
• Altered mental status 2, 3
• Lactate >3 mmol/L (indicates severe sepsis requiring immediate intervention) 3

If sepsis criteria present: Initiate broad-spectrum empiric antibiotics within 1 hour, aggressive fluid resuscitation, and vasopressor support if hypotension persists despite fluids. 3

Special Populations

Elderly Patients with Respiratory/Inflammatory Disease

In older adults, particularly those in long-term care facilities, neutrophilia has heightened diagnostic importance because these patients frequently lack typical infection symptoms (fever, obvious focal findings) due to decreased basal body temperature and blunted immune responses. 1, 2 Left shift becomes the primary laboratory indicator of serious bacterial infection in this population. 1, 2

Context-Specific Interpretations

In respiratory disease contexts:

• Neutrophilia in bronchoalveolar lavage (>5% neutrophils) suggests underlying fibrosing processes including idiopathic pulmonary fibrosis, fibrosing alveolitis of rheumatological disease, asbestosis, or fibrotic sarcoidosis 4
• In refractory asthma, increased airway neutrophils represent a different inflammatory process than typical eosinophilic asthma and are poorly responsive to corticosteroids 4
• Neutrophils are the predominant inflammatory cell in status asthmaticus when death occurs within several hours of attack 4

Non-Infectious Causes to Consider

Medication-Induced

• Lithium, beta-agonists, and epinephrine can cause neutrophilia with left shift 1
• Corticosteroids may paradoxically prolong neutrophil survival by decreasing apoptosis, potentially worsening neutrophilia 4

Hematologic Disorders

• Myelodysplastic syndromes can show left shift as a dysplastic feature in granulocytopoiesis 1

Thrombotic Risk

• Persistent neutrophilia ≥9.0 × 10⁹/L is associated with doubled risk of venous thromboembolism (OR 2.0), independent of cancer, infection, or steroids 5
• Risk increases further with neutrophil counts ≥10.0 × 10⁹/L (OR 2.3) 5

Critical Pitfalls to Avoid

1. Do not rely on automated differential alone—manual count is mandatory to accurately assess band forms 1, 2, 3

2. Do not ignore left shift when total WBC is normal—this combination still indicates significant bacterial infection 1, 2, 3

3. Do not obtain urinalysis/urine culture in truly asymptomatic patients (especially nursing home residents) as bacteriuria is nearly universal and does not indicate infection 2

4. Do not delay antibiotics in severe sepsis/septic shock while awaiting culture results 3

5. Do not treat based solely on laboratory findings if patient is truly asymptomatic and hemodynamically stable after thorough assessment 2, 3

6. In elderly patients, do not assume absence of infection based on lack of fever or typical symptoms—left shift may be the only indicator 1, 2