Hema-

• Hematology


  The study of blood cells
• Athanasius Kircher (1657) described worms in the blood
• Anton van Leeuwenhoek (1674) gave an account of RBCs
• Giulio Bizzozero (late 1800s) described platelets as "petites plaques"
• James Homer Wright (1902) developed Wright stain
• In the present day, Hematology laboratory is analyzed by automation
• Functions of blood


  • Transport oxygen from lungs to tissues
  • Clear tissues of carbon dioxide
  • Transport glucose, proteins, and fats
  • Move waste to the liver and kidneys
• The average human has 5 liters of blood
• Plasma


  Liquid portion of anticoagulated blood
• Serum


  Liquid portion of a clotted blood
• Anti-coagulant


  Not coagulant, unclotted
• Coagulant


  Clotted, with fibrinogen
• Three categories of blood cells

  • Red blood cells or erythrocytes
  • White blood cells or leukocytes
  • Platelets or thrombocytes
• Red blood cells


  • Biconcave, discoid cells
  • Filled with hemoglobin which transports oxygen and carbon dioxide
  • Appear pink to red, 6-8um in diameter with a zone of pallor in the center
• Anemia


  Loss of oxygen carrying capacity reflected in a reduced RBC count or decreased RBC hemoglobin concentration
• Polycythemia


  Increased RBC count reflecting increased circulating RBC mass, leading to hyperviscosity
• RBC counting


  1. Carefully pipette a tiny aliquot of whole blood

  2. Mix with 0.85% normal saline solution with a dilution of 1:200

  3. Transfer to a glass counting chamber called Hemocytometer
• Osmosis


  The movement of water in a semipermeable membrane from a lower solute concentration to a higher solute concentration
• Isotonic


  Same osmolality or solute concentration as another solution, RBCs will neither shrink nor swell
• Hypotonic


  Solute concentration is lesser than the other solution, RBCs will swell and eventually lyse
• Hypertonic


  Solute concentration is greater than the other solution, RBCs will shrink or crenate
• The Coulter counter principle is based on direct current electrical impedance
• White blood cells/Leukocytes


  • A loosely related category of cell types dedicated to protecting their host from infection and injury
  • Counted with the same technique as RBCs but with a typical dilution of 1:20 and a dilute acid solution as the diluent
• Leukocytosis


  WBC count of >11,500
• Leukopenia


  WBC count of <4500
• Types of WBCs


  • Neutrophils
  • Eosinophils
  • Basophils
  • Lymphocytes
  • Monocytes
• Neutrophilia


  Increase in neutrophils, common cause: Bacterial infection
• Neutropenia


  Decrease in neutrophils, common cause: certain medications or viral infections
• Left shift


  Increase in band neutrophils, commonly found in bacterial infection
• Eosinophilia


  Elevated eosinophil count, signifies a response to allergy or parasitic infection
• Basophilia


  Rare, often signals a hematologic disease
• Lymphocytosis


  Associated with viral infections
• Lymphocytopenia


  Associated with drug therapy or immunodeficiency
• Monocytosis


  Associated with collagen-vascular disease, or in acute and chronic leukemias
• Platelets/Thrombocytes


  • True blood cells that maintain blood vessel integrity by initiating vessel wall repairs
  • Come from the cytoplasm of the megakaryocytes
  • Function: Adhere/Adhesion to the site of injury, Aggregate/Aggregation with other platelets to form the platelet plug, Secret/Secretion the contents of their granules
  • Only 6-8um round or oval, and anucleate
• Thrombocytosis


  Increase in platelet count
• Thrombocytopenia


  Decrease in platelet count
• Complete Blood Count


  1. Performed on automated blood cell analyzers to assess adequate blood cells

  2. The MLS is responsible for the integrity of the specimen and ensures: Proper anticoagulant used, Free of clots, Not hemolyzed, Sufficient in volume, Tested within turn-around time

  3. If one result is abnormal, the instrument will display a flag and a blood film examination is performed

  4. If results are normal, a blood film examination is not needed
• Blood Film Examination


  1. Prepare a wedge-prep blood film on a glass slide, allow it to dry, and fix and stain it using Wright or right-Giemsa stain

  2. Use 40x objective for WBCs, 100x oil immersion objective for platelets

  3. Review, identify, and tabulate 100 (or more) WBCs to determine their percentage distribution aka the WBC differential/Diff count

  4. Examine the morphology of blood cells using 1000x magnification
• Main function of blood film examination

  Confirm/verify the results of automated analyzers