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White Blood Cell

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White Blood Cell, WBC Count, White Blood Cell Count, Leukocyte, Leukopenia, Granulocyte

  • Physiology
  • White Blood Cells (Leukocytes, WBC)
  1. Bone Marrow: Stem cells differentiation and storage
    1. Megakaryoblasts
      1. Platelets
    2. Erythroblasts
      1. Erythrocytes
    3. Lymphoblasts
      1. Lymphocytes (20-40% of peripheral WBCs)
    4. Myeloblasts develop into Granulocytes
      1. Neutrophil (40-60 of peripheral WBCs)
      2. Eosinophil (1-4% of peripheral WBCs)
      3. Basophil (0.5-1% of peripheral WBCs)
      4. Monocyte (2-8% of peripheral WBCs)
  2. Peripheral Blood
    1. Leukocytes remain in storage in Bone Marrow: 80-90%
      1. Proliferate and mature over 7 days
      2. Stored in the marrow up to 7 days
    2. Only 2-3% of Leukocytes enter circulation (unless mobilized)
      1. Life span of White Blood Cell in circulation 2-16 days
      2. Life span of White Blood Cell in body tissues 36 hours
  • Interpretation
  • Normal Range White Blood Cells (in 10^9/L)
  1. Age 12 hours old: 13.0 to 38.0
  2. Age 2 weeks old: 5.0 to 20.0
  3. Age 6 Months to 2 years: 6.0 to 17.5 (Mean 11.0)
  4. Age 4 Years: 5.5 to 15.5 (Mean 9.1)
  5. Age 6 Years: 5.0 to 14.5 (Mean 8.5)
  6. Age 8 to 16 Years: 4.5 to 13.5 (Mean 8.1)
  7. Age over 21 Years: 4.5 to 11.0 (Mean 7.4)
  8. Third trimester: 5.8 to 13.2
  9. Postpartum: Up to 12.6
  • Interpretation
  • Increased White Blood Cell Count
  1. See Leukocytosis
  2. Neutrophilia (>7000/mm3 or >60%, most common cause)
  3. Lymphocytosis (>4500/mm3 or >40% of total)
  • Interpretation
  • Decreased White Blood Cell Count (Leukopenia)
  1. Neutropenia (most common cause)
  2. Lymphocytopenia
  3. Monocytopenia
  4. Eosinopenia