Hematology Lab Terms

Hematology

Definitions

• Anemia: deficiency of hemoglobin or RBC
• Coagulation department: section of the lab concerned with the clotting mechanism of the blood
• CBC: complete blood count, tests for WBC, RBC, Hgb, Hct, indices, and differential
• EDTA: ethylenediaminetetraacetic acid, an anticoagulant used in hematology tubes
• ESR: erythrocyte sedimentation rate, used to determine if inflammation is present
• Hemacytometer: counting chamber for manual WBCs, RBCs, platelets, and sperm counts
• Hematology department: section of the lab that studies blood cells
• Hemoglobin: substance in RBCs that carries oxygen and CO2
• Hemostasis: stoppage of bleeding
• Platelets (thrombocytes): cells involved in the clotting of blood
• Red blood cell indices: calculations to determine the size and contents of red blood cells
• Red blood cells (erythrocytes): cells containing hemoglobin that transport O2 to the body and CO2 away to the lungs
• Reticulocyte (Retic): immature RBC
• White blood cells (leukocytes): cells involved in infection control and immunity
• Wrights Stain: a stain used in hematology for doing differentials

CBC

• WBC count: determines if a patient has an infection (↑WBC) or whether the immune system is compromised (↓ WBC)
• RBC count: may indicate anemia (↓) or polycythemia (↑)
• Hemoglobin: carries O2 to cells and CO2 away
• Hematocrit: reflects the relationship between the amount of RBCs and the amount of plasma in a blood sample
• Normal range for Hgb: 120-160 g/L for females, 140-180 g/L for males
• Normal range for Hct: 0.35-0.47 L/L for females, 0.4-0.52 L/L for males

Red Blood Cell Indices

• MCV: mean corpuscular volume, expresses the average volume of RBCs
• MCH: mean corpuscular hemoglobin, estimates the weight of hgb in RBC
• MCHC: mean corpuscular hemoglobin concentration, expresses the concentration of hgb in RBCs relative to their size
• Normal values: MCV 80-100 fl, MCH 27-32 pg/cell, MCHC 32-37 g/dl

Anemia

• Four types:
  • Iron deficiency anemia: caused by a decrease in iron, treatment is iron supplements
  • Pernicious anemia: caused by a lack of intrinsic factor, treatment is Vitamin B12 injections
  • Aplastic anemia: failure of bone marrow to produce enough RBCs, treatment is bone marrow transplant
  • Hemolytic anemia: caused by excessive destruction of RBCs, treatment is splenectomy

Platelet Count

• May be done on an automatic cell counter or manually on a hemacytometer
• Normal value: 250,000-450,000 per cubic ml

Blood Smears

• Two types: thick and thin blood smears
• Thick blood smear: often used to detect malaria
• Thin blood smear: used to perform a manual differential
• Qualities of a good smear: gradual transition from thick to thin, smooth appearance, no ridges or holes, feathered edge

Wrights Stain

• Used to stain blood smears
• Procedure: make slides, stain with Wrights stain, add buffer, wash, and let air dry

Differential

• Consists of three parts:
  • WBC differential count: counts the number of neutrophils, lymphocytes, monocytes, eosinophils, and basophils in 100 WBCs
  • RBC morphology: examines the size, shape, and amount of hemoglobin in RBCs
  • Platelet estimation: estimates the platelet count and platelet morphology

Other Tests

• Retic count: measures the number of reticulocytes in the blood
• ESR: measures the rate of sedimentation of RBCs
• Nasal smear: examines the nasal mucosa for eosinophils
• Cold agglutinins: autoantibodies produced in response to infection or autoimmune hemolytic anemia
• Cryofibrinogen and cryoglobulin: proteins that precipitate when cold

Role of the Med Lab Assistant

• Draws specimens for hematology
• Makes and stains blood smears
• Sets up blood to be run by the automated cell counter
• Performs quality control tasks
• Helps with inventory maintenance
• Performs manual tests under the supervision of a technologist