What does an elevated neutrophil count indicate?

Elevated Neutrophil Count of 81.4%: Causes and Clinical Significance

A neutrophil percentage of 81.4% indicates moderate neutrophilia, which is most commonly associated with bacterial infection but can also be caused by inflammation, stress, medications, or certain diseases. This finding warrants clinical correlation and possibly further investigation depending on patient symptoms and clinical context.

Common Causes of Neutrophilia

• Bacterial infections are the most common cause of neutrophilia, with bacterial infection having a high likelihood ratio when neutrophil count is elevated 1
• An increase in the percentage of neutrophils (>90%) has a likelihood ratio of 7.5 for bacterial infection 1
• Specific bacterial infections commonly causing neutrophilia include:
  • Respiratory tract infections 1
  • Urinary tract infections 1
  • Skin/soft tissue infections 1
  • Gastrointestinal infections 1
  • Spontaneous bacterial peritonitis in patients with cirrhosis 1

Non-Infectious Causes

• Inflammatory conditions such as rheumatoid arthritis, vasculitis, or inflammatory bowel disease 1
• Physiologic stress including surgery, trauma, burns, or emotional stress 1
• Medications that can cause neutrophilia include:
  • Lithium 1
  • Beta-agonists 1
  • Epinephrine 1
  • Corticosteroids 1
• Cardiovascular conditions - elevated neutrophil count is associated with higher risk of major adverse cardiac events including myocardial infarction 2
• Malignancies, particularly leukemias and myeloproliferative disorders 1

Clinical Significance and Approach

• The presence of an elevated neutrophil percentage (81.4%) warrants careful assessment for bacterial infection, even without fever 1
• A complete blood cell count with differential should be performed to determine the absolute neutrophil count 1
• Manual differential is preferred to assess bands and other immature forms 1
• A left shift (≥16% band neutrophils) has a likelihood ratio of 4.7 for bacterial infection, even with a normal total WBC count 1

Diagnostic Algorithm

1. Assess for symptoms of infection or inflammation:

   • Fever, localized pain, or other signs of systemic inflammation 1
   • If present, perform focused evaluation based on symptoms

2. Review complete blood count:

   • Check total WBC count - elevation >14,000 cells/mm³ strongly suggests infection 1
   • Evaluate for left shift (increased band forms) 1
   • Look for other abnormalities (anemia, thrombocytopenia, etc.) 1

3. Consider specific clinical scenarios:

   • In patients with cirrhosis and ascites: Perform diagnostic paracentesis to rule out spontaneous bacterial peritonitis (SBP) 3
   • In patients with respiratory symptoms: Consider chest imaging 3
   • In patients with cardiovascular risk factors: Evaluate for possible cardiac involvement 2, 4

4. Additional testing based on clinical suspicion:

   • Blood cultures if systemic infection suspected 3
   • Imaging studies directed at suspected source of infection 3
   • Inflammatory markers (CRP, ESR) to assess inflammation 1

Common Pitfalls

• Overlooking the significance of neutrophil percentage elevation when total WBC count is only mildly elevated 1
• Treating asymptomatic patients with antibiotics based solely on mildly elevated neutrophil counts 1
• Failing to consider non-infectious causes of neutrophilia 1
• Not recognizing that neutrophil counts can be influenced by time of day, exercise, and stress 5

Special Considerations

• In patients with cirrhosis and ascites, a neutrophil count >250 cells/mm³ in ascitic fluid indicates spontaneous bacterial peritonitis requiring immediate antibiotic treatment 3
• Neutrophilia can be a marker of cardiovascular risk - studies have shown an association between elevated neutrophil count and adverse cardiovascular outcomes in postmenopausal women with hypertension 4