Diagnostic Tests Associated with the Immune System

White Blood Cells (WBC)

• Normal Range: 5,000 - 10,000 WBC per microliter
  • Leukocytosis: WBC count > 10,000
    • Indicates potential infection
  • Leukopenia: WBC count < 4,000
    • Causes: Cancer, autoimmune disorders, certain medications, infections
    • High risk for infection due to insufficient WBCs

Neutrophils

• Normal Range: 2,500 - 8,000
  • Neutropenia: Neutrophils < 2,000
  • Left Shift/Banded Neutrophils:
    • Occurs when bone marrow releases immature neutrophils due to overwhelming infection
    • Analogy: Like sending immature soldiers when adult soldiers aren’t sufficient in a war

Erythrocyte Sedimentation Rate (ESR)

• Normal Level: < 20 mm/hr
  • Elevated ESR indicates inflammation in the body

C-Reactive Protein (CRP)

• Normal Level: < 3 mg/L
  • Elevated CRP indicates inflammation
  • Memory Aid: CRP has three letters, so normal levels < 3

Differential White Blood Cell Count

• Helps determine type of infection, cancer, or autoimmune disorder

Types of White Blood Cells

1. Neutrophils
   • Percentage: 55-75%
   • Elevated in acute bacterial infections
   • "First responders" to neutralize threats
2. Lymphocytes
   • Percentage: 20-40%
   • Elevated in bacterial, viral infections, leukemia, and lymphoma
3. Monocytes
   • Percentage: 2-8%
   • Elevated in bacterial infections and tuberculosis
4. Eosinophils
   • Percentage: 1-4%
   • Elevated in allergic reactions and parasitic infections
5. Basophils
   • Percentage: 0.5-1%
   • Elevated in allergic reactions
   • Release histamine; may require antihistamines like Benadryl
   • Memory Aid: Basophils -> Benadryl for allergic reactions

Next Topics

• The next video will cover immune disorders, starting with Lupus.