RBC evaluation

erythrocyte function

• Transport Oxygen to tissue
• Transport Carbon Dioxide to lungs

• Buffer H+

PCV

High-speed centrifugation to separate blood into cell layers based on

density

impedance

Measures the electrical resistance of cells in a fluid as they pass through an aperture

optical flow

Cells categorized based on light scatter and internal complexity

outer lipid bilayer function

• Maintain deformability and integrity of RBC

• Semi-permeable for gas exchange
• Maintains environment for Hgb to function

erythrocyte antioxidant pathways

• RBC membrane and hemoglobin are particularly susceptible to oxidative injury
• RBCs generate protective reducing agents to neutralize potentially harmful effects. (antioxidants)
• Enzymes:Glutathioneperoxidase,superoxidedismutase,catalase,etc • Antioxidants:Glutathione,VitaminC,VitaminE,etc

hemoglobin function

• transport of oxygen from the lungs to tissues

• transport CO2 from tissue to lungs

• 
  

carbonic anhydrase

enzyme that converts CO2 to H+ and HCO3- to be transported to the lungs

carbaminohemoglobin

CO2 binds directly to hemoglobin, 20% of CO2 is transported this way

oxygen carrying capacity

• RBC

• Hgb

• HCT

• PCV

wintrobes RBC indices

• MCV

• MCHC

• MCH

• used to characterize RBC

erythropoietic activity

• reticulocytes

• RDW

• nRBC

PCV

• percentage of packed RBCs within a given volume of blood (centrifugation)

HCT

• Calculated value generated by hematology analyzer

• only reliable if MCV and RBC are accurate

• should be within 3% of PCV

hemoglobin

Measured by lysing the RBCs -> oxidizing Hgb -> Formation of Heme products that are detected spectrophotometrically

• Any substance that interferes with sample turbidity can cause false elevation in Hbg

• • Lipemia(post-prandialsampling)
  • Intravascular hemolysis (hemoglobinemia)
  • Heinz bodies

• hgb is 1/3 of the HCT

RBC

measured by

1. hemocytometer

2. automated impedance counter

3. automated flow cytometer

4. RBC agglutination or clotting can falsely decreased rbc conc

hemocytometer

manual method

automated impedance counter

• Cells are drawn through an aperture and cause electrical resistance

• Degree of resistance differentiates Plt, RBC, and WBC

automated flow cytometer

• Cells individually pass through a laser beam

• Size, number, and internal complexity are determined by scatter of the laser beam

MCV

mean corpuscular volume - mean vol per RBC

MCH

• mean corpuscular hemoglobin

• mean hgb per RBC

MCHC

mean corpuscular hemoglobin concentration

• mean Hgb concentration per RBC

macrocytosis

• increased MCV (larger erythorcytes)

microcytosis

• decreased MCV (smaller erythrocytes)

macrocytosis is caused by

artifacts, prolonged storage, hyperosmolality, breed associated, regenerative anemia, etc

microcytosis is caused by

artifact (excess EDTA), hyponatremia, young animals, breed associated, iron deficiency and portosystemic shunt.

hyperchromasia

increased MCHC, always an artifact

hypochromasia

decreased MCHC, due to regenerative anemia, iron deficiency (most common)

erythropoietic activity

reticulocytes, RDW, nRBC

reticulocytes

• non-nucleated, immature RBCs with stainable cytoplasmic RNA

• used to categorize anemias as regenerative or non regenerative

• assessed by

• 1. manual counts, incubated with methylene blue to precipitate DNA, per 1000 rbc

• 2. routine blood smear (wright stain)- polychromasia due to increased RNA content

• 3. automated counts and absolute reticulocyte concentration to evaluate marrow response to anemia

no

do horses release reticulocytes?

2

how many stages of reticulocytes are observed in cats?

aggregate and punctate

stages of reticulocytes in cats

cattle

Reticulocytes do not occur in high numbers until the anemia is severe

dogs

• Normal to have low numbers in health (~1.5% of erythrocytes)

• Reticulocytosis without anemia: corticosteroids, NSAIDs, catecholamine-induced splenic contraction, etc

RDW

Calculated value that reflects the variation in RBC volume (anisocytosis)

• Younger RBCs will have high MCV -> if they are in high enough concentration, they will increase the RDW

nRBC

nucleated red blood cell in circulation

• Assessed on a blood smear

reveals regenerative anemia, bone marrow injury, splenic function, heat stroke, lead poisoning, etc

Erythrocyte Blood Smear Assessment

• Density

• Arrangement

• Size and variation in size

• Shape changes

• Inclusions

density

• Crude visual assessment of hematocrit

arrangement

• rouleau= linear aggregates/ coin stacks cause by charge interactions (normal in cats and horses)

• agglutination- grape clusters caused by IGs bindng to RBC antigens

normal shape

• Discocytes:Biconcave disc with central pallor
• Elliptocyte/Ovalocyte: Elongated RBC with no central pallor (camels)
• Nucleated elliptocyte RBC

poikilocytes

abnormal shape associated with underlying pathology

acanthocyte

Irregularly spaced projections of various lengths

echinocyte

• burr cell

• regularly spaced pointy projections

codocyte

• target cell

• • Central focus of Hgb that is surrounded by a ring of pallor that separates it from peripheral Hgb

dacrocyte

teardrop to pear shaped

eccentrocyte

• bite cell

• eccentric dense-staining Hgb and adjacent clear space

leptocyte

thin cell that contains less Hgb

elliptocyte

elongated RBC

schistocyte

RBC fragment

spherocyte

Round RBC with no central pallor and decreased cell diameter

stomatocyte

Elongated area of cytoplasmic pallor (slit- like or mouth-like)

color

Changes in color are affected by the RNA and Hgb content

ghost cells

RBC cell membrane with little to no residual cytoplasmic Hgb

basophilic stippling

• Seen with regenerative anemia in cattle and plumbism

heinz bodies

• Oxidized Hgb that precipitates and binds to the RBC membrane

• Highlighted with new methylene blue stain

howell jolly bodies

• Small nuclear remnant, typically a homogeneous dark purple circle
• Low numbers can be seen in healthy animals and in splenectomized animals