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Hemic-Lymphatic and Clin Path > Hematology Methods > Flashcards

Hematology Methods Flashcards

1
Q

what are the red blood cell indices on a complete blood count?

A

mean cellular volume
mean cellular hemoglobin
mean cellular hemoglobin concentration

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2
Q

what does EDTA do?

A

prevents platelet aggregation and clot formation

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3
Q

how does impedance technology work?

A

cells in buffer solution are pulled through an electrical field
cells are poor electrical conductors: resistance results in a voltage pulse proportional to cell size

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4
Q

what do aliquot 1 and 2 do in impedance instruments?

A

aliquot 1: red blood cells and platelets counted
aliquot 2: red blood cells and white blood cells lysed (platelets excluded)

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5
Q

how does impedance separate cells?

A

size

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6
Q

what is used to identify cells in flow cytometry?

A

differences in light scatter by going through laser beam

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7
Q

what are the disadvantages of impedance instruments?

A

none work on birds or reptiles
daily maintenance required
differential counts less accurate with disease

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8
Q

what is more accurate with flow cytometry?

A

white blood cell differential counts
platelet and red blood cell counts

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9
Q

why would you heat a hematocrit tube at 56 C for 3 minutes?

A

precipitate fibrinogen out: measure differences to get fibrinogen concentration
large animals and rabbits

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10
Q

why would you want to measure fibrinogen?

A

early marker inflammation
higher before changes in white blood cells

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11
Q

what increases fibrinogen?

A

inflammation
pregnancy
dehydration
foals <6 months

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12
Q

what are the major acute phase proteins?

A

C-reactive protein
serum amyloid A

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13
Q

what are the advantages of a manual cell count?

A

requires a microscope: you see what you’re counting
fixed price per test

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14
Q

what things is a microscopic exam needed to identify?

A

immature white blood cells
large atypical lymphocytes, basophils
mast cells
nucleated/abnormal red blood cells
white blood cell inclusions
platelet clumps
microfilaria

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15
Q

hemoglobin should be ____ of PCV

A

1/3

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16
Q

what are some causes of a lower than expected hemoglobin?

A

defect in hemoglobin formation (iron deficiency)
analyzer malfunction

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17
Q

what are some causes of a higher than expected hemoglobin?

A

always an artifact
sample interference
free hemoglobin (hemolysis)

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18
Q

what are some sample age errors?

A

platelet clumping decreases count
leukocyte morphologic changes
red blood cell changes

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19
Q

in whom does EDTA cause hemolysis?

A

some reptiles and birds

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20
Q

does heparin prevent platelet clumping?

A

no

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21
Q

what are the two main types of hematology instruments?

A

impedance analyzers
flow cytometry

22
Q

what are the options for plasma color?

A

normal
icteric
hemolysis
hemolysis (severe)
lipemic

23
Q

what are the disadvantages of manual cell counts?

A

very labor intensive
high error rate: only counting 100s of cells, losing track of which cells you counted, over- and under-filling introduces chamber error

24
Q

in whom are instrument white blood cell differential counts most accurate?

A

healthy animals

25
Q

does EDTA cause hemolysis?

A

in some reptiles and birds

26
Q

how are platelets and red blood cells separated in impedance instruments?

A

size

27
Q

why are platelets excluded from lysing in impedance instruments?

A

size

28
Q

what does side scatter, not forward light scatter, detect in flow cytometry?

A

intracellular inclusions

29
Q

are differential counts less accurate with disease?

A

yes

30
Q

what is more accurate with flow cytometry?

A

white blood cell differential counts
platelet and red blood cell counts

31
Q

what can increase plasma protein?

A

lipemia

32
Q

how can you measure fibrinogen with heat precipitation?

A

measure plasma protein, then heat to 56 degrees C for 3 minutes
measure plasma protein again: difference of 0.5g/dL is 500mg/dL

33
Q

what would make a fibrinogen by heat precipitation measurement inaccurate?

A

lipemia
hemolysis

34
Q

how long does it take for fibrinogen to increase with inflammation?

A

1-2 days

35
Q

is fibrinogen increased with dehydration?

A

yes

36
Q

how can you correct for dehydration when measuring fibrinogen by heat precipitation?

A

TP-fibrinogen/fibrinogen
if <15, inflammation
if >20, dehydration

37
Q

is automated hematocrit directly measured or calculated?

A

calculated:
MCVxRBC/10

38
Q

what is mean cell hemoglobin concentration affected by?

A

red blood cell count and red blood cell ssize

39
Q

increased MCHC is a sign of an ______________

A

artifact

40
Q

decreased MCHC can be a sign of _________________

A

low hemoglobin levels

41
Q

what are the components of a CBC?

A

WBC and RBC counts and morphologic features
hematocrit
hemoglobin concentration
RBC indices
WBC differential count
platelet count and estimate
maybe reticulocyte counts

42
Q

how is free hemoglobin measured in the second aliquot of impedance analyzers?

A

colorimetrically

43
Q

forward light scatter is proportional to ________________ and side scatter detects __________________

A

size and shape
intracellular inclusions

44
Q

what are some additional methods that some flow cytometers add?

A

fluorescent dye
peroxidase staining

45
Q

when are fibrinogen measurements by heat precipitation inaccurate?

A

lipemia
hemolysis

46
Q

what values of total protein/fibrinogen are consistent with inflammation in horses and cattle?

A

<15 for horses
<10 for cattle

47
Q

how much do the major acute phase proteins increase with inflammation?

A

10-1000x

48
Q

what is mean cell hemoglobin concentration affected by?

A

RBC size and count

49
Q

what is increased mean cell hemoglobin concentration a sign of?

A

an artifact

50
Q

what can happen morphologically with leukocytes with sample age?

A

nuclear swelling or pyknosis
cytoplasmic vacuolization

Hemic-Lymphatic and Clin Path (33 decks)

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