How to interpret a blood routine test

🥼 Practice and Clinical
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Original Video

[Clinical Beginner Series: Laboratory Tests (2): Interpretation and Management of Complete Blood Count Results - The Most Complete on Bilibili]
https://www.bilibili.com/video/BV1Xz4y137Jr

Summary of Complete Blood Count

  • White Blood Cell Count Related Indicators: Bacterial Infection/Leukemia
    • [[White Blood Cell Count]], [[White Blood Cell Differential Count]], [[Neutrophil Count]], [[Nuclear Morphology Changes of Neutrophils]]
    • Increased neutrophil count and neutrophil percentage (＞70%)
      • Bacterial infection: Especially pyogenic cocci; note that Gram-negative bacilli infections can increase or decrease
      • Major trauma/major bleeding: Reactive increase (overstimulation of hematopoiesis to increase red blood cells)
      • Acute poisoning: Ketoacidosis, uremia, chemical drug poisoning, etc. increase
      • Leukemia/malignant tumors (before treatment): Leukemia greatly increased, tumors increased
      • Considerations
        • WBC increase = bacterial infection?
        • Neutrophil count + neutrophil percentage increase = bacterial infection?
        • ①② + increased proportion of band neutrophils = bacterial infection?
    • Decreased neutrophil count and neutrophil percentage (≤50%)
      • WBC < 4\times10^9, neutrophils < 1.5\times10^9, granulocytopenia; neutrophils < 0.5\times10^9 is agranulocytosis
        • Most common causes: chemical toxins, radiation damage (generally refers to side effects of chemotherapy and radiotherapy in medicine)
        • Certain Gram-negative bacilli and viral infections may cause neutrophil decrease
        • Hematologic diseases: pancytopenia (reduction of red cells, white cells, and platelets)
      • Granulocyte colony-stimulating factor treatment: recombinant human granulocyte colony-stimulating factor (long-acting and short-acting)
        • Do not forcefully use granulocyte growth factors before chemotherapy (like new soldiers entering battle)
        • Short-acting: mature within 48 hours after injection, then chemotherapy; otherwise, new cells are easily killed by chemotherapy drugs
        • Long-acting: wait until chemotherapy drugs are metabolized (5-7 days) before injection
  • Other Infection Markers
    • [[C-reactive protein CRP]], [[erythrocyte sedimentation rate ESR]] have high sensitivity but poor specificity
    • [[Procalcitonin PCT]] has high specificity and is useful for guiding bacterial infection diagnosis
      • ![[Procalcitonin PCT]]
  • Anemia
    • [[Hemoglobin concentration measurement and red blood cell count]]: very severe - 30, severe - 60, moderate - 90, mild - 110, none
      • Blood transfusion if acute anemia below 70
      • Blood transfusion if chronic anemia below 60
      • Do not get hung up on borderline values
    • [[Hematocrit HCT]], [[reticulocyte count]]
    • [[Mean corpuscular volume MCV]], [[mean corpuscular hemoglobin MCH]], [[mean corpuscular hemoglobin concentration MCHC]] to determine anemia type
      • See [[Anemia Classification]] for details
  • [[Platelet count PLT]] (PLT): coagulation function
  • [[Changes in lymphocyte count]]: leukemia (pathological lymphocyte increase), nutritional status
  • [[Changes in monocyte count]]: viral infections
  • [[Changes in eosinophil count]]: parasites, allergic reactions
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