Download Veterinary Practice Laboratory Unit 1

Hematology
Unit 2
Chapter 9
Hemoglobin, PCV, and Erythrocyte
Indices
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.
Complete Blood Count
• CBC includes
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Total RBC count
PCV
Plasma protein concentration
Total WBC count
Blood film examination
• Differential WBC count, RBC and leukocyte
morphology
• Reticulocyte count if anemic
• Hemoglobin concentration
• Erythrocyte indices
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Packed Cell Volume (PCV)
• Percentage of whole blood composed of
RBCs
• Microhematocrit tubes
• Red ring – heparinized
• Blue ring – not treated
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Packed Cell Volume (cont.)
• RBC – high specific gravity
• Dark red layer
• Buffy coat
• Whitish-gray layer above the RBC layer
• Consists of WBCs and platelets
• Height – rough estimate of total WBC count
• Plasma
• Clear to pale yellow fluid
• Top layer
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Packed Cell Volume (cont.)
• Plasma layer
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Normal – clear to pale yellow
Cloudy – lipemic
Reddish tinge – hemolyzed
Deep yellow – icteric
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Packed Cell Volume (cont.)
• Hematocrit reading tube
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Packed Cell Volume (cont.)
• Significance of results
• Pathologic condition
• Below normal
• Anemia
• Inadequate volume of blood to anticoagulant ratio
• Above normal
• Polycythemia
• Dehydrated
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Plasma Protein Concentration
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Plasma from the hematocrit tube
Refractometer
Measured in g/dL
Lipemic samples
• False increase in the total protein reading
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Hemoglobin Testing
• Functional unit of the RBC
• Heme portion
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Contains iron
• Globin
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Amino acids
• Synthesis during maturation of RBCs
• Different forms
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Oxyhemoglobin – oxygen replaces CO2 in
respiration
Methemoglobin – occurs naturally
Sulfhemoglobin – results from cell aging
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Erythrocyte Indices
• Help classify anemia
• Provide an objective measure of the size
and average hemoglobin concentration
• Accuracy dependent upon:
• Total RBC count
• PCV
• Hemoglobin concentration
• Compare values to morphologic features
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Mean Corpuscular Volume
• MCV measures average size of RBCs
• Divide PCV by RBC concentration and
multiply by 10
Example:
Dog has a PVC of 42%, RBC count of 6.0 million/mL
42/6 x 10 = 70 fL (femtoliters)
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Mean Corpuscular Hemoglobin
• Mean weight of hemoglobin contained in
the average RBC
• Divide the hemoglobin concentration by
the RBC concentration and multiply by 10
Example:
Hemoglobin concentration of 14 g/dL and RBC
concentration of 7 million/mL
14/7 × 10 = 20 pg (picograms)
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Mean Corpuscular Hemoglobin
Concentration
• Concentration of hemoglobin in the
average RBC
• Divide the hemoglobin concentration by
the PCV and multiply by 100
Example:
Hemoglobin concentration of 14 g/dL and PVC of 42%
14/42 × 100 = 33.3 g/dL
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Summary
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Cell counts
Packed cell volumes
Plasma protein concentration
Hemoglobin testing
Erythrocyte indices
• MCV
• MCH
• MCHC
Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.
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