MedCram Lecture: Understanding Leukocytosis and WBC Counts

Introduction to CBC

• Focus on White Blood Cells (WBC) and leukocytosis.
• Normal WBC range: 4.5 to 11 (x10^9 per liter).
• Leukocytosis defined as WBC > 11.
• Importance of monitoring trends in WBC counts.

Understanding WBC Components

• WBCs are part of the immune system and comprise various cells:
  • Neutrophils: Bands and segmented (segs).
  • Lymphocytes: Often elevated in viral infections.
  • Monocytes: Can be elevated in tuberculosis and viral infections.
  • Eosinophils: Elevated in allergies, parasites, and possibly coccidioidomycosis.

Differential WBC Count

• Bands and segs usually around 60%.
• Lymphocytes around 20%.
• Monocytes around 5%.
• Eosinophils around 2-4%.

Causes of Leukocytosis

1. Infection:

   • Look for left shift (increase in bands).
   • Check for fever and infection signs.
   • Diagnostic tests: Chest X-ray, urinalysis, CT scan, lumbar puncture.
   • Common infections: Pneumonia, UTIs, cellulitis.

2. Steroids:

   • Causes WBC to rise due to demargination, delayed migration, and minor bands release.
   • WBC increase usually modest (e.g., 12 to 20).
   • Key indicator: No left shift or bandemia.

3. Leukemia/Lymphoma:

   • Overproduction or lack of death of WBCs.
   • Types include acute and chronic lymphocytic and myelogenous leukemia.
   • Check LAP score for cancer indication.
   • Peripheral smear and possible bone marrow biopsy needed for diagnosis.

4. Catastrophic Events:

   • Myocardial infarction, cardiac arrest, massive pulmonary embolism.
   • Transient increase in WBC count due to systemic stress.

Conclusion

• Other triggers for leukocytosis include cold showers and other stressors.
• Always consider the broader clinical picture and corroborating evidence when evaluating WBC counts.

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These notes provide a comprehensive overview of leukocytosis, WBC count variations, and their implications, suitable for students and practitioners to understand key concepts and clinical approaches.