Labmath

• Hematology


  Study of blood cells and coagulation
• Hematology encompasses analyses of

  • Concentration, structure, and functions of blood cells
  • Blood cell precursors in the bone marrow
  • Chemical constituents of plasma or serum intimately linked with blood cell structure and function
  • Function of platelets and proteins involved in blood coagulation
• Red Blood Cells (RBC)

  • Erythrocytes, Anucleate, Biconcave, Discoid cells
  • Hemoglobin: Reddish protein that transports oxygen and carbon dioxide
  • Appear salmon pink
  • Size: 7 to 8 mm in diameter with a zone of pallor that occupies one third of their center
• Counting of RBCs


  • Laboratory professionals count RBCs in measured volume to detect anemia or polycythemia
  • Anemia: Loss of oxygen-carrying capacity, Reduced RBC count or decreased hemoglobin concentration
  • Polycythemia: Increased RBC count, Increased RBC mass
• Reticulocytes


  Young RBCs contains RNA, Differentiation and counting is done by staining the peripheral blood smear using methylene blue dyes
• White Blood Cells (WBC)

  Leukocytes, Function: protect their host from infection and injury, Transported in the blood, from their source such as bone marrow or lymphoid tissues, to their tissue or body cavity destination
• Counting of WBCs


  • Leukopenia: decreased WBC count
  • Leukocytosis: increased WBC count
• Platelets


  • Thrombocytes, Function: maintain blood cell integrity by initiating vessel wall repairs, Only 2 - 4 micrometers in diameter, round, or oval, anucleate cells, Also known as cell fragments
  • Thrombocytosis: signal inflammation or trauma
  • Thrombocythemia: extremely high platelet counts and uncontrolled platelet production
  • Thrombocytopenia: low platelet count due to drug treatment
• Performing Manual Cell Enumeration

  1. Collected blood is diluted using a special diluent

  2. A small amount of diluted blood is transferred into a hemacytometer

  3. Counting of cells is done under the microscope

  4. Counts are reported as number of cells per mm²
• Hemacytometer


  Neubauer counting chamber, Ruled glass platform used to count the three major blood cells, RBCs, WBCs, and Platelets, H-shaped moat separates the two identical ruled glass platforms, Each platform is a 3mm × 3mm ruled square subdivided into 9 large squares, Each large square is 1 mm × 1 mm, The 4 large corner squares (labeled W) are further subdivided into 16 squares which are used for counting white blood cells, The large center square is divided into 25 smaller squares and is further subdivided into 16 squares each resulting to 400 tiny squares in total, The large center square designated for counting red blood cells and platelets, 5 smaller squares marked by "R"s are used for counting red blood cells while the whole large center square is used for counting platelets, Flanking the ruled glass platforms are two raised ridges on which the cover glass rests, There is a distance of exactly 0.1 mm between the cover glass and the surface of the ruled counting area, Because the counting area measures 3 mm x 3 mm x 0.1 mm, its volume is 0.9 mm³, Through the V-shaped indentation, diluted blood enters the hemacytometer by capillary action into the counting area, where the cells are enumerated microscopically, Afterward, the procedure is repeated on the other side of the hemacytometer, and the two counts are averaged

  
• Counting White Blood Cells

  1. Dilution: 1:20 in a weak acid

  2. Count total WBCs in all 4 corner squares from both sides of the hemacytometer

  3. Get the average for the number of cells counted

  4. The difference between two counts must be less than 10

  5. The difference between the highest and lowest count of any of these two counts must be less than 15

  6. Volume: 1mm x 1mm x 0.1mm x 4 (since 4 squares were counted) = 0.4mm³

  7. Area: 1mm x 1mm x 4 (since 4 squares were counted) = 4mm²

  8. Depth: 0.1mm
• Counting Red Blood Cells

  1. Dilution: 1:200 in 0.85% saline solution

  2. Count total RBCs in all R squares of the large central square from both sides of the hemacytometer

  3. Get the average for the number of cells counted

  4. Volume: 0.04 mm² x 0.1mm x 5 = 0.02mm³

  5. Area: 0.04 mm² x 5 (since 5 squares were counted) = 0.2mm²

  6. Depth: 0.1mm
• Counting Platelets


  1. Dilution: 1:100

  2. Count total Platelets in all 25 small squares of the large central square from both sides of the hemacytometer

  3. Get the average for the number of cells counted

  4. Volume: 0.04 mm² x 0.1mm x 25 = 0.1mm³

  5. Area: 0.04 mm² x 25 (since 25 squares were counted) = 1mm²

  6. Depth: 0.1mm
• RBC COUNT — REFERENCE RANGE

  • Male: 4.20 - 6.00 × 10¹²/L
  • Female: 3.80 - 5.20 × 10¹²/L

  
• Hematocrit (Hct)


  Volume of whole blood occupied by packed RBCs, Blood is loaded into a capillary tube and centrifuged, Hematocrit value is read using a microhematocrit reader and reported as a percentage of the total volume, Example: An Hct of 42% means that RBCs take up 42 of every 100 mL of whole blood

  
• Rule of Three


  A simple but effective check on the integrity of the measurements and calculations that went into the hemoglobin concentration, hematocrit, and RBC count: 3 × RBC Count = Hb, 3 × Hb = Hct