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Chapter 41
Hematology
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Hematologic Tests
• Second most common type of tests performed in POL
• Cellular components of blood affected by changes in organs or tissues of body
• Click here to see an animation
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Types of Blood Tests
• Hemoglobin• Hematocrit• White blood cell
(WBC) count• Red blood cell (RBC)
count• Platelet count
• Differential WBC count
• Erythrocyte sedimentation rate (ESR)
• Prothrombin time
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Hematologic Tests
• Results of tests provide valuable information for diagnosis, evaluating patient’s progress, or regulating further treatment
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Complete Blood Count
• Hemoglobin determination
• Hematocrit determination
• WBC count
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Complete Blood Count
• RBC count
• Differential WBC count
• Erythrocyte indices
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Hemoglobin and Hematocrit
• Hemoglobin– Major component of erythrocyte and carrier of oxygen
in body; 85 percent of dry weight of RBC
– Synthesis of heme requires iron
– Adult male requires 0.5 mg/day of iron
– Menstruating female requires 2 mg/day of iron
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Hemoglobin and Hematocrit
• Hemoglobin– Carries 95 percent of oxygen to cells
– Transports 27 percent of carbon dioxide back to lungs for removal
– Acts as buffer system
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Hemoglobin and Hematocrit
• Hematocrit– Separation of blood into liquid portion and solid
portion by process of centrifugation
– Erythropoietin• Hormone that triggers production of new red cells
– Hemoglobinopathies• Group of diseases; abnormal forms of hemoglobin
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Hemoglobin and Hematocrit
• Hematocrit– Iron deficiency anemia
• Near-normal hematocrit with low hemoglobin value; hypochromic RBC lack hemoglobin
• Determining hemoglobin values– Cyanmethemoglobin
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Hemoglobin and Hematocrit
• Normal hemoglobin values or reference ranges by age or sex
• Normal hematocrit values or reference ranges by age or sex
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Hemoglobin and Hematocrit
• Microhematocrit– Centrifuge
– Packed cell column showing separation of cellular components >>
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WBC and RBC Counts
• WBC and RBC counts– Automated method
• WBC differential– Normal leukocyte counts
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Leukocyte Identification Guide
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Leukocyte Differentiation
• Groups– Myelocytic or granulocytic series
– Lymphocytic
– Monocytic
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Leukocyte Differentiation
• Granulocytic group– Neutrophil
– Eosinophil
– Basophil
• Differential leukocyte count
• Normal values for a differential leukocyte count in adults
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Erythrocyte Indices
• Include:– Mean corpuscular volume (MCV)
– Mean corpuscular hemoglobin (MCH)
– Mean corpuscular hemoglobin concentration (MCHC)
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Erythrocyte Indices
• Provide information about size of RBC and hemoglobin content
• Normal values
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Erythrocyte Indices
• Using erythrocyte indices to diagnose– MCH and MCV increased in megaloblastic anemias
– MCH and MCV decreased in hypochromic and microcytic anemias
– MCHC increased in hereditary spherocytosis
– MCHC normal in macrocytosis
– MCHC decreased in iron deficiency anemia
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Erythrocyte Sedimentation Rate
• Measures rate at which RBC fall toward bottom when placed in vertical tube >>
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Erythrocyte Sedimentation Rate
• Also called “sed rate”
• Used in diagnosis and treatment of many diseases– Inexpensive
– Accurate
– Easy to perform
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Erythrocyte Sedimentation Rate
• Wintrobe method– EDTA venous blood sample mixed
– Blood transferred with Pasteur pipette to Wintrobe tube
– No air bubbles
– Place tube vertically in rack to stand for 60 minutes
– Read number of millimeters red cells settled
– Normal values for Wintrobe method of ESR
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Erythrocyte Sedimentation Rate
• Westergren method– Mix blood sample with 3.8 percent sodium citrate
solution before filling tube
– Normal values for Westergren method of ESR
– Sediplast ESR system
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Erythrocyte Sedimentation Rate
• Guidelines for Wintrobe and Westergren ESR procedures to measure accurate results
Rouleaux >>
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Erythrocyte Sedimentation Rate
• Using the ESR to diagnose– ESR increased in infections and inflammatory diseases,
tissue destruction, and other conditions leading to increased plasma fibrinogen
– ESR increased with anemia, menstruation, pregnancy, malignant neoplasms, and multiple myeloma
– ESR normal in osteoarthritis, some cases of cirrhosis, and malaria
– ESR decreased in polycythemia, spherocytosis, and sickle cell anemia
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Coagulation Studies
• Prothrombin Time (PT)– “Protime”
– Measures time it takes a patient’s blood to clot
– Normal blood clots in 11-13 seconds
• International Normalized Ratio (INR)– Can be universally applied
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Automated Hematology Instrumentation and Quality Control • Hematology instruments that require
sample dilutions
• Hematology instruments that do not require sample dilutions
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Automated Hematology Instrumentation and Quality Control
• CLIA ’88 regulation for quality control in automated hematology
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Automated Hematology Instrumentation and Quality Control• Required procedures
– Calibration
– Control samples
– Proficiency testing
• Check manufacturer’s recommendations for particular piece of equipment