Hematology Flashcards
How do you estimate the leukocyte number? What power do you do it at?
-10x
-count leukocytes in 3-4 fields in the monolayer and calculate the average
-divide average number by 4 in order to approximate number of leukocytes x 10^9/L
How do you estimate platelet number? What power do you do it at?
-100x
-count platelets in 10 fields and calculate average
-multiply average by 20 x 10^9/L
*comment if platelets are clumped (if so=underestimates
-if greater than 10/100 field=adequate
-less than 3-4/100 field=significant thrombocytopenia
Dog erythrocytes
-largest RBC
-prominent central pallor
Cat erythrocytes
-intermediate size RBC
-lack central pallor
-often form rouleaux
Cow erythrocytes
-smallest RBC
-lack central pallor
Horse erythrocytes
-intermediate size RBC
-lack central pallor
-often form rouleaux
-no polychromasia
Horse platelets
-indistinct, pale staining with irregular barely discernible membranes and a few indistinct granules
What is agglutionation?
-clumping of erythrocytes due to antibody interactions
-tends to form grape-like clusters
*indicates immune-mediated disease
How can you differentiate rouleaux from agglutination?
-a drop of saline added to a drop of EDTA blood will result in dispersion of rouleaux, but agglutination will persist
What shows evidence of regeneration?
-polychromatophils
>number correlates with the intensity of the regenerative response
*rarely seen in horses (ex. use macrocytes instead)
-macrocytes, hypochromasia, nuclear remnants and low numbers of nucleated erythrocytes may be seen
Reticulocytes vs. polychromatophils
-same cell but different stain
-reticulocytes=new methylene blue
Aggregate vs. punctate reticulocytes
-punctate=individual blue dots
>cats: they persist in circulation for a long period (do NOT provide info about the current anemia)
-aggregate=have clumps or strands of precipiated RNA
How do you determine the percentage of reticulocytes?
-count the number of reticulocytes per 1000 erythrocytes
-if more than 1%=regenerative
>percentage may overestimate them so ABSOLUTE reticulocyte is preferred
How do you determine the absolute reticulocyte count?
-multiple the reticulocyte percentage by RBC count in the CBC
*note: reticulocyte count is expressed in 10^9/L, so make sure to CHANGE from 10^12/L to 10^9/L
What is happening in iron-deficiency anemia?
-occurs when there is chronic or recurrent external blood loss (ex. GI tract)
*results in loss of iron=can not recycle the erythrocytes
>effects erythropoiesis=MICROCYTOSIS and HYPOCHROMASIA
-might be regenerative to begin but then become non-regenerative
What features do you look for in iron-deficiency anemia?
-MICROCYTOSIS and HYPOCHROMASIA
-variable numbers of polychromatophils
-aniscytosis
-may see erythrocyte fragments due to INCREASED cell fragility
-may see increased number of platelets
What is happening in oxidative damage hemolytic anemia?
-formation of Heinz bodies and/or eccentrocytes
>Heinz bodies=precipated aggregates of denatured hemoglobin (prominently seen in methylene blue smears)
>eccentrocytes=form when cell membrane is oxidized and bonds to itself
*more fragile=more likely to be trapped and destroyed by the spleen=anemia
What are some causes of oxidative damage to erythrocytes?
-acetaminophen: especially cats (but also dogs)
-zinc: dogs
-wilted red maple leaves: horses
-kale: cows
*onions in ALL species
What features do you look for in oxidative damage hemolytic anemia?
-Heinz bodies and/or eccentrocytes
>Heinz bodies can be seen in healthy, non-anemic cats (does NOT always indicate disease)
-blister cells and keratocytes sometimes
-*expect a robust regenerative response if enough time has elapsed
>polychromatophils, macrocytes, nuclear remnants, nucleated erythrocytes
What is happening in immune-mediated hemolytic anemia?
-results from antibody-mediated destruction of erythrocytes
>idiopathic
>secondary to various causes (ex. drugs/toxins, incompatible blood transfusions, infectious agents)
*spherocyte formation=loss of erythrocyte membrane without decrease in erythocyte volume
What features do you look for in immune-mediated hemolytic anemia?
*sperocytosis (usually only detected in dogs)
-might see: ghost cells, erythrocyte agglutination
-expect robust regenerative response if enough time has elapsed
-might note increased WBC numbers including bands (inflammatory leukogram)
-keratocytes and schizocytes sometimes seen (due to be abnormally fragile cells)
When does fragmentation anemia occur?
-hostile vascular environment that causes physical injury to erythrocytes=results in erythrocyte fragments
>strands of fibrin cause mechanical fragmentation and formation of SCHIZOCYTES and KERATOCYTES (Ex. dog with DIC and formation of microthrombi)
>acantocytes in dogs with hemangiosarcoma
-turbulent blood flow
What features can be seen in other anemias with poikilocytes?
-schizocytes, keratocytes, or acanthocytes
-expect a robust regenerative response if enough time as elapsed
-platelets may be decreased in both DIC and hemangiosarcoma
Band vs. segmented neutrophils
-nuclear shape: nuclear borders are parallel to each other for majority of the band nucleus
-chromatin pattern: segmented have more clumped (clumped chromatin indicates maturity)
-nuclear construction: segs have tight constrictions (<1/2 width of thickest part)
-cell size: bands larger
-cytoplasm colour: bands may have bluer cytoplasm
