Hematology Methods

Question 1

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

Answer 1

mean cellular volume
mean cellular hemoglobin
mean cellular hemoglobin concentration

Question 2

what does EDTA do?

Answer 2

prevents platelet aggregation and clot formation

Question 3

how does impedance technology work?

Answer 3

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

Question 4

what do aliquot 1 and 2 do in impedance instruments?

Answer 4

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

Question 5

how does impedance separate cells?

Answer 5

size

Question 6

what is used to identify cells in flow cytometry?

Answer 6

differences in light scatter by going through laser beam

Question 7

what are the disadvantages of impedance instruments?

Answer 7

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

Question 8

what is more accurate with flow cytometry?

Answer 8

white blood cell differential counts
platelet and red blood cell counts

Question 9

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

Answer 9

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

Question 10

why would you want to measure fibrinogen?

Answer 10

early marker inflammation
higher before changes in white blood cells

Question 11

what increases fibrinogen?

Answer 11

inflammation
pregnancy
dehydration
foals <6 months

Question 12

what are the major acute phase proteins?

Answer 12

C-reactive protein
serum amyloid A

Question 13

what are the advantages of a manual cell count?

Answer 13

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

Question 14

what things is a microscopic exam needed to identify?

Answer 14

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

Question 15

hemoglobin should be ____ of PCV

Answer 15

1/3

Question 16

what are some causes of a lower than expected hemoglobin?

Answer 16

defect in hemoglobin formation (iron deficiency)
analyzer malfunction

Question 17

what are some causes of a higher than expected hemoglobin?

Answer 17

always an artifact
sample interference
free hemoglobin (hemolysis)

Question 18

what are some sample age errors?

Answer 18

platelet clumping decreases count
leukocyte morphologic changes
red blood cell changes

Question 19

in whom does EDTA cause hemolysis?

Answer 19

some reptiles and birds

Question 20

does heparin prevent platelet clumping?

Answer 20

no

Question 21

what are the two main types of hematology instruments?

Answer 21

impedance analyzers
flow cytometry

Question 22

what are the options for plasma color?

Answer 22

normal
icteric
hemolysis
hemolysis (severe)
lipemic

Question 23

what are the disadvantages of manual cell counts?

Answer 23

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

Question 24

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

Answer 24

healthy animals

Question 25

does EDTA cause hemolysis?

Answer 25

in some reptiles and birds

Question 26

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

Answer 26

size

Question 27

why are platelets excluded from lysing in impedance instruments?

Answer 27

size

Question 28

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

Answer 28

intracellular inclusions

Question 29

are differential counts less accurate with disease?

Answer 29

yes

Question 30

what is more accurate with flow cytometry?

Answer 30

white blood cell differential counts platelet and red blood cell counts

Question 31

what can increase plasma protein?

Answer 31

lipemia

Question 32

how can you measure fibrinogen with heat precipitation?

Answer 32

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

Question 33

what would make a fibrinogen by heat precipitation measurement inaccurate?

Answer 33

lipemia hemolysis

Question 34

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

Answer 34

1-2 days

Question 35

is fibrinogen increased with dehydration?

Answer 35

yes

Question 36

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

Answer 36

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

Question 37

is automated hematocrit directly measured or calculated?

Answer 37

calculated: MCVxRBC/10

Question 38

what is mean cell hemoglobin concentration affected by?

Answer 38

red blood cell count and red blood cell ssize

Question 39

increased MCHC is a sign of an ______________

Answer 39

artifact

Question 40

decreased MCHC can be a sign of _________________

Answer 40

low hemoglobin levels

Question 41

what are the components of a CBC?

Answer 41

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

Question 42

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

Answer 42

colorimetrically

Question 43

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

Answer 43

size and shape intracellular inclusions

Question 44

what are some additional methods that some flow cytometers add?

Answer 44

fluorescent dye peroxidase staining

Question 45

when are fibrinogen measurements by heat precipitation inaccurate?

Answer 45

lipemia hemolysis

Question 46

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

Answer 46

<15 for horses <10 for cattle

Question 47

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

Answer 47

10-1000x

Question 48

what is mean cell hemoglobin concentration affected by?

Answer 48

RBC size and count

Question 49

what is increased mean cell hemoglobin concentration a sign of?

Answer 49

an artifact

Question 50

what can happen morphologically with leukocytes with sample age?

Answer 50

nuclear swelling or pyknosis cytoplasmic vacuolization