INTRO TO HEMA

• Hematology


  The study of blood cells
• The average human possesses 5 liters of blood
• Functions of blood


  • Transports oxygen from lungs to tissues
  • Clears tissues of carbon dioxide
  • Transports glucose, proteins, and lipids
  • Moves wastes to the liver and kidneys
• Plasma


  The liquid portion of blood that provides coagulation enzymes and transports and nourishes blood cells
• Categories of blood cells

  • Red blood cells (RBCs, erythrocytes)
  • White blood cells (WBCs, leukocytes)
  • Platelets (PLTs, thrombocytes)
• By expertly staining, counting, analyzing, and recording the appearance, phenotype, and genotype of all three types of cells, the medical laboratory professional is able to predict, detect, and diagnose blood diseases and many systemic diseases that affect blood cells
• Physicians rely on hematology laboratory test results to select and monitor therapy for these disorders
• A complete blood count (CBC) is ordered on nearly everyone who visits a physician or is admitted to a hospital
• Athanasius Kircher described "worms" in the blood


  1657
• Anton van Leeuwenhoek gave an account of RBCs


  1674
• Giulio Bizzozero described platelets as "petites plaques"


  Late 1800s
• James Homer Wright developed the Wright stain


  1902
• Wright's Romanowsky-type stain (polychromatic, a mixture of acidic and basic dyes), and refinements thereof, remains the foundation of blood cell identification
• Morphology


  The scientific term for cell appearance, which encompasses cell color, size, shape, cytoplasmic inclusions, and nuclear condensation
• Red blood cells (RBCs)

  • Anucleate, biconcave, discoid cells filled with hemoglobin, which transports oxygen and carbon dioxide
  • Appear salmon pink and measure 7 to 8 µm in diameter with a zone of pallor that occupies one third of their center, reflecting their biconcavity
• Anemia


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


  An increased RBC count reflecting increased circulating RBC mass, a condition that leads to hyperviscosity
• Hemoglobin (HGB)


  Measured using Drabkin reagent, which converts hemoglobin to stable cyanmethemoglobin (hemiglobincyanide)
• Hematocrit (HCT)


  The ratio of the volume of packed RBCs to the volume of whole blood, manually determined by centrifugation
• RBC indices


  Mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), and red blood cell distribution width (RDW)
• Reticulocytes


  Polychromatic (polychromatophilic) erythrocytes, newly released from the bone marrow, which indicate the ability of the bone marrow to increase RBC production in anemia
• White blood cells (WBCs, leukocytes)


  A loosely related category of cell types dedicated to protecting their host from infection and injury
• Leukopenia


  Decreased WBC count
• Leukocytosis


  Increased WBC count
• Types of WBCs in peripheral blood

  • Neutrophils (NEUTs, segmented neutrophils [SEGs], polymorphonuclear neutrophils [PMNs])
  • Bands (band neutrophils, BANDs)
  • Eosinophils (EO)
  • Basophils (BASO)
  • Lymphocytes (LYMPH)
  • Monocytes (MONO)
• Neutrophils (NEUTs, segmented neutrophils [SEGs], polymorphonuclear neutrophils [PMNs])


  Phagocytic cells whose major purpose is to engulf and destroy microorganisms and foreign material, either directly or after they have been labeled for destruction by the immune system. The term segmented refers to their multilobed nuclei. The cytoplasm of neutrophils contains pink- or lavender-staining granules filled with bactericidal substances.
• Neutrophilia


  Increase in neutrophils, often signals bacterial infection
• Neutropenia


  Decrease in neutrophils, often caused by certain medications or viral infections
• Bands (band neutrophils, BANDs)


  Slightly less mature neutrophils with a nonsegmented nucleus in a U or S shape. An increase in bands also signals bacterial infection and is customarily called a left shift.
• Eosinophils (EOs)


  Cells with round, bright orange-red cytoplasmic granules filled with proteins involved in immune system regulation. An elevated eosinophil count is called eosinophilia and often signals a response to allergy or parasitic infection.
• Basophils (BASOs)


  Cells with dark purple, irregular cytoplasmic granules that obscure the nucleus. The basophil granules contain histamines and various other proteins. An elevated basophil count is called basophilia. Basophilia is rare and often signals a hematologic disease.
• Granulocytes


  Neutrophils, bands, eosinophils, and basophils are collectively called granulocytes because of their prominent cytoplasmic granules, although their functions differ.
• Lymphocytes (LYMPHs)


  Comprise a complex system of cells that provide for host immunity. Lymphocytes recognize foreign antigens and mount humoral (antibodies) and cell-mediated antagonistic responses. On a Wright-stained blood film, most lymphocytes are nearly round, are slightly larger than RBCs, and have round featureless nuclei and a thin rim of nongranular cytoplasm.
• Lymphocytosis


  Increase in the lymphocyte count, often associated with viral infections. Accompanying lymphocytosis are often reactive lymphocytes with characteristic morphology.
• Lymphopenia or lymphocytopenia


  Abnormally low lymphocyte count, often associated with drug therapy or immunodeficiency.
• Monocytes (MONOs)


  Immature macrophages passing through the blood from their point of origin, usually the bone marrow, to a targeted tissue location. On a Wright-stained blood film, monocytes have a slightly larger diameter than other WBCs, blue-gray cytoplasm with fine azure granules, and a nucleus that is usually indented or folded.
• Monocytosis


  Increase in the number of monocytes, may be found in certain infections or in inflammation.
• Medical laboratory professionals seldom document a decreased monocyte count, so the theoretical term monocytopenia is seldom used.
• Leukemia


  Uncontrolled proliferation of a clone of malignant WBCs. May be chronic (e.g. chronic myeloid leukemia or chronic lymphocytic leukemia) or acute (e.g. acute myeloid leukemia or acute lymphoblastic leukemia).
• Chronic lymphocytic leukemia is more prevalent in people older than 65 years, whereas acute lymphoblastic leukemia is the most common form of childhood leukemia.