MedCram Lecture: Understanding Leukocytosis in CBC

Introduction

• Lecture focuses on leukocytosis, an increased WBC (White Blood Cell) count.
• Normal WBC range: 4.5 - 11 (times 10^9 cells per liter).
• Leukocytosis: WBC > 11, can go up to 100,000.
• Important to observe trends in WBC counts.

Understanding Leukocytosis

• Definition: Increase in WBC above normal range.
• Significance of Trends:
  • Decreasing trend (e.g., 20 to 13) may indicate resolution.
  • Increasing trend (e.g., 5 to 13) is concerning.

White Blood Cells (WBC) Components

• Types of WBCs:
  • Bands and Segmented Neutrophils (SEGs): Indicative of pyogenic infections.
  • Lymphocytes: Typically elevated in viral infections.
  • Monocytes: Can be elevated in TB or viral infections.
  • Eosinophils: Elevated in allergies, parasitic infections, and coccidioidomycosis (fungal).

WBC Functions and Indicators

• Normal WBC Distribution:
  • Bands and SEGs: ~60%.
  • Lymphocytes: ~20%.
  • Monocytes: ~5%.
  • Eosinophils: 2-4%.
• Deviations:
  • Elevated lymphocytes: Think viral infections.
  • High SEGs: Think bacterial infections.
  • Elevated eosinophils: Consider allergies, parasites, or coccidioidomycosis.

Causes of Leukocytosis

1. Infection:

   • Look for left shift (increased bands).
   • Indicators: Fever, signs of infection (e.g., pain).
   • Diagnostic tests: Chest X-ray, urinalysis, CT scan, lumbar puncture.
   • Common infections: Pneumonia, UTI, cellulitis, cholecystitis, diverticulitis.

2. Steroids:

   • Cause D-margination (redistribution of WBCs in blood vessels).
   • Causes increase in WBC count without left shift.
   • Look for proportional increase in lymphocytes, neutrophils, and monocytes.

3. Cancer/Leukemia:

   • Abnormal production or survival of WBCs.
   • Types: Acute/Chronic lymphocytic, myelogenous leukemia.
   • Low LAP (Leukocyte Alkaline Phosphatase) score indicates cancer.
   • Diagnostic approach: Peripheral smear, pathologist review, possible bone marrow biopsy.

4. Catastrophic Event:

   • Events like MI, cardiac arrest, massive PE, surgery cause transient WBC increase.

Additional Information

• Other triggers for leukocytosis include stress, physical events (like cold showers).

Conclusion

• Careful evaluation of WBC trends and differential is crucial for diagnosis.
• Understanding underlying causes aids in appropriate clinical decisions.

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• Remember, accurate diagnosis and treatment often require correlation with clinical findings and further diagnostic testing.