Hematology Flashcards

1
Q

How do you estimate the leukocyte number? What power do you do it at?

A

-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

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2
Q

How do you estimate platelet number? What power do you do it at?

A

-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

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3
Q

Dog erythrocytes

A

-largest RBC
-prominent central pallor

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4
Q

Cat erythrocytes

A

-intermediate size RBC
-lack central pallor
-often form rouleaux

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5
Q

Cow erythrocytes

A

-smallest RBC
-lack central pallor

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6
Q

Horse erythrocytes

A

-intermediate size RBC
-lack central pallor
-often form rouleaux
-no polychromasia

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7
Q

Horse platelets

A

-indistinct, pale staining with irregular barely discernible membranes and a few indistinct granules

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8
Q

What is agglutionation?

A

-clumping of erythrocytes due to antibody interactions
-tends to form grape-like clusters
*indicates immune-mediated disease

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9
Q

How can you differentiate rouleaux from agglutination?

A

-a drop of saline added to a drop of EDTA blood will result in dispersion of rouleaux, but agglutination will persist

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10
Q

What shows evidence of regeneration?

A

-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

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11
Q

Reticulocytes vs. polychromatophils

A

-same cell but different stain
-reticulocytes=new methylene blue

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12
Q

Aggregate vs. punctate reticulocytes

A

-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

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13
Q

How do you determine the percentage of reticulocytes?

A

-count the number of reticulocytes per 1000 erythrocytes
-if more than 1%=regenerative
>percentage may overestimate them so ABSOLUTE reticulocyte is preferred

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14
Q

How do you determine the absolute reticulocyte count?

A

-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

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15
Q

What is happening in iron-deficiency anemia?

A

-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

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16
Q

What features do you look for in iron-deficiency anemia?

A

-MICROCYTOSIS and HYPOCHROMASIA
-variable numbers of polychromatophils
-aniscytosis
-may see erythrocyte fragments due to INCREASED cell fragility
-may see increased number of platelets

17
Q

What is happening in oxidative damage hemolytic anemia?

A

-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

18
Q

What are some causes of oxidative damage to erythrocytes?

A

-acetaminophen: especially cats (but also dogs)
-zinc: dogs
-wilted red maple leaves: horses
-kale: cows
*onions in ALL species

19
Q

What features do you look for in oxidative damage hemolytic anemia?

A

-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

20
Q

What is happening in immune-mediated hemolytic anemia?

A

-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

21
Q

What features do you look for in immune-mediated hemolytic anemia?

A

*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)

22
Q

When does fragmentation anemia occur?

A

-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

23
Q

What features can be seen in other anemias with poikilocytes?

A

-schizocytes, keratocytes, or acanthocytes
-expect a robust regenerative response if enough time as elapsed
-platelets may be decreased in both DIC and hemangiosarcoma

24
Q

Band vs. segmented neutrophils

A

-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

25
Q

What is left shift a hallmark of?

A

-acute inflammation
>release of increased numbers of immature neutrophils

26
Q

What is a degenerative left shift?

A

-total neutrophil count is with RI or decreased
-immature forms approach or surpass mature forms in number
*poor/worse prognosis

27
Q

Adult cattle and neutrophils

A

-have a lower reserve of mature neutrophils=develop a degenerative left shift more readily
>prognosis not necessarily as poor as in other species
-leukocyte response of young calve are more similar to adult dogs than adult cattle

28
Q

What is toxic change a sign of?

A

-immaturity
>accelerated transit of cells through the maturation pool in the bone marrow=when peripheral demand for granulocytes is increased
*refers to cytoplasmic features only

29
Q

What are four features of toxic change?

A
  1. Dohle bodies
  2. Basophilic cytoplasm
  3. Foamy cytoplasm
  4. (retention of primary granules=toxic granulation=RARE finding)
30
Q

Monocytes vs. reactive lymphocytes

A

-lymphocytes: develop indented nuclei and a large amount of cytoplasm
*compare colour of nucleus and cytoplasm to cells you are sure are monocytes or lymphocytes

31
Q

What are metamyelocytes?

A

-can be seen when peripheral demand for neutrophils is extreme
-less mature than band neutrophils
-kidney bean shaped nucleus and immature chromatin
-may be slightly larger than bands
-can be difficult to differentiate from monocytes when toxic change is present
*rare finding and only expected with a left shift

32
Q

What is Pelger-Huet anomaly?

A

-uncommon hereditary disorder in dogs, cats and horses
-causes mature granulocytes to be hyposegmented (lack normal tight constrictons)
>may think they are bands
*on a slide: neutrophils have mature chromatin despite hyposegmentation (bands would have immature chromatin)
-eosinophils and basophils nuclei is also present

33
Q

Nucleated RBCs and corrected WBC count

A

-when increased number of nucleated RBCs, the WBC generalized by the hematology analyzer must be corrected to account for nucleated RBCs
*if nRBCs > 5 per 100 WBC then use following formula
*Corrected WBC count = (WBC x 100) divided by (100+nRBCs)

34
Q

What is leukemia?

A

-presence of neoplastic cells in peripheral blood
-classified as acute or chronic

35
Q

What does acute leukemia present as?

A

-immature blast cells (ex. lymphoblasts or myeloblasts) in the blood smear
-rapidly fatal unless treated

36
Q

What does chronic leukemia present as?

A

-detected on routine bloodwork
-well differentiated cells (Ex. small lymphocytes or neutrophils) seen in blood smear
-disease can be indolent: animal can live a long time even w/o treatment

37
Q

What are blast cells?

A

-immature cells of any hematopoietic lineage
>do not have many distinguishing features=undifferentiated blasts
-large round cells with round nuclei and one or more nucleoli

38
Q

What are basket cells?

A

-ruptured cells
>neoplastic cells are fragile and may rupture during sample collection
-very large and often get dragged to feathered edge