2 HEMATOLOGY

• Hematology


  Study of the formed (cellular) elements of the blood
• Hematology Section

  • Cellular elements, red blood cells (RBCs), white blood cells (WBCs), and platelets (Plts)
  • Detect disorders such as leukemia, anemia, other blood diseases, and infection and monitor their treatment

  
• Whole blood


  Most common body fluid analyzed in the hematology section, a mixture of cells and plasma
• Anticoagulant


  EDTA (Ethylenediamine tetraacetic acid) to prevent clotting of the sample
• Blood


  The body's main fluid for transporting nutrients, waste products, gasses, and hormones through the circulatory system
• Plasma

  Liquid portion of anticoagulated blood, contains the protein fibrinogen, comprises approximately 55% of the total blood volume

  
• Serum


  Liquid portion of clotted blood

  
• Erythrocytes


  The Red Blood Cells, anucleate biconcave disks that are approximately 7.2 microns in diameter, contain the protein hemoglobin to transport oxygen and carbon dioxide, life span: 120 days
• Leukocytes


  The White Blood Cells, provide immunity to certain diseases by producing antibodies and destroying harmful pathogens by phagocytosis, normal number: 4,500 to 11,000 per microliter of blood

  
• White blood cell count


  Determines the number of all WBC present in the blood
• Differential cell count


  Determines the percentage of each type of leukocyte
• Types of leukocytes

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


  The most numerous leukocytes (40-60%), provide protection against infection through phagocytosis, called "segmented" or "polymorphonuclear cells"
• Lymphocytes


  The second most numerous leukocytes (20-40%), provide the body with immune capability by means of B and T lymphocytes
• Monocytes


  1. 3-8%, largest circulating leukocytes, act as a powerful phagocytes to digest foreign material, a tissue monocyte is known as a macrophage
• Eosinophils

  1. 1-3%, red orange granules, and the nucleus has only two lobes (bilobes), detoxify foreign proteins and increase in allergies, skin infections, and parasitic infections
• Basophils

  0-1%, least common of the leukocytes, the cytoplasm contains large granules that stain purple-black, release histamine in the inflammation process and heparin to prevent abnormal blood clotting
• Thrombocytes


  The Platelets, small, irregularly shaped disks formed from the cytoplasm of very large cells in the bone marrow called the megakaryocytes, life span: 9-12 days, average number: between 140,000 and 440,000 per microliter of blood, play a vital role in blood clotting in all stages of the coagulation mechanism
• Complete Blood Count (CBC)


  The primary analysis performed in the hematology section, very often it is ordered on a STAT basis, series of different tests
• Tests included in CBC

  • Differential (Diff)
  • Hematocrit (Hct)
  • Hemoglobin (Hgb)
  • Indices
  • Mean corpuscular hemoglobin (MCH)
  • Mean corpuscular hemoglobin concentration (MCHO)
  • Mean corpuscular volume (MCV)
  • Platelet (PLT) count
  • Red blood cell (RBC) count
  • Red cell distribution width (RDW)
  • White blood cell (WBC) count
• Other tests performed in the hematology section

  • Body fluid analysis
  • Bone marrow
  • Erythrocyte sedimentation rate (ESR)
  • Reticulocyte (Retx) count
  • Sickle cell
  • Special stains
• Coagulation section


  Sometimes a part of the hematology section, but in larger laboratories, it is a separate section, tests here is not as open as the hematology section, specimen: Plasma from light blue stopper tubes (Sodium citrate), the overall process of hemostasis is evaluated
• Tests performed in the coagulation section

  • Activated partial thromboplastin time (APTT (PTT))
  • Antithrombin Ill
  • Anti-Xa heparin assay
  • Proteins Cand 5
  • Bleeding time (BT)
  • D- dimer
  • Factor assays
  • Fibrin degradation products (FDP)
  • Fibrinogen
  • Platelet aggregation
  • Prothrombin time (PT) and international normalized ratio INRI
  • Thrombin time (TT)
• Blood smears


  Needed for the microscopic of blood cells that is performed for the differential blood cell count, for special staining procedures, and for non-automated reticulocyte counts, should be collected before other samples to avoid platelet clumping, obtained by dermal puncture or venipuncture (EDTA within 1 hour of collection)

  
• Ideal blood smear

  Smooth film of blood that covers approximately one-half to two thirds of the slide, does not contain ridges or holes, has a lightly feathered edge without streaks (ends)
• Technical errors on blood smear

  • Uneven distribution of blood (ridges)
  • Holes in the smear
  • No feathered edge
  • Streaks in the feathered edge
  • Smear too thick and short
  • Smear too thin and long