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Clinical Pathology Exam 1 > Lecture 7 - Platelets > Flashcards

Lecture 7 - Platelets Flashcards

1
Q

Fibrin formation after vascular injury causes vessel wall to

A

vasoconstrict and activate hemostasis process

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2
Q

Fibrin formation after vascular injury causes vessel wall to

A

vasoconstrict and activate hemostasis process

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3
Q

platelets form an initial unstable platelet plug also during __

A

primary hemostasis

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4
Q

__ form definitive hemostatic plug in secondary hemostasis by making a stable fibrin clot

A

coagulation factors

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5
Q

Sites of extramedullary hematopoeisis where platelets may arise

A
  1. lungs
  2. spleen
  3. liver
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6
Q

__ are the precursors to platelet cells

A

megakaryocytes

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7
Q

4 factors that can contribute to abnormal platelet concentrations

A

production
consumption
destruction
redistribution (shifting of platelets to/from circuation)

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8
Q

most platelet production occurs in the

A

BM

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9
Q

__ is when platelets are removed from circulation during normal maintenance or during accelerated states such as thrombotic dz and vasculitis

A

consuption

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10
Q

Destruction of platelets occurs by macrophages in the __ and __

A

spleen and liver

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11
Q

platelets can sequester in the __ and this redistribution may reduce circulating platelet mass, contraction may increase it

A

spleen

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12
Q

explain the 4 steps of primary hemostasis (platelet “bricks”)

A
  1. adhesion
  2. shape change
  3. granule release
  4. aggregation
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13
Q

4 things found in platelet DENSE granules that are released after binding which activate more platelets

A
  1. ADP
  2. ATP
  3. Serotonin
  4. Ca++
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14
Q

3 things found in platelet ALPHA granules

A
  1. adhesion proteins - von willebrand factor
  2. growth factors
  3. coagulation proteins
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15
Q

platelets have what types of granules

A

dense and alpha - contain different things

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16
Q

What granules contain von willebrand’s factors

A

alpha granules

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17
Q

__ stimulates megakaryocyte and platelet production

A

thrombopoeitin

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18
Q

what is the most useful ddx/gold standard for evaluating platelets

A

peripheral blood film! estimate #, look for clumps, observe morphology (megaplatelet, degranulated?)

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19
Q

challenging to get accurate platelet counts in __ and __

A

cats (large and clumpy)

horses (clump in EDTA, use citrate)

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20
Q

Platelet indicies are similar to RBC indicies

A

MPV, PDW, PCT, MPC (mean platelet content)

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21
Q

how do you evaluate megakaryocyte number

A

BM cytology

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22
Q

cat platletes

A

larger with higher MPV (mean platelet volume)

sensitive to activation (clumping, degranulate)

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23
Q

Platelets are estimated on 100x in the __, to estimate platelets use formula

A

monolayer

estimated platelet count/mcL = average count in 10 fields x 20,000

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24
Q

average amount of platelets on 100x field for dogs/cats __, horses __

A

8-12/field

6/field

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25
Q

platelets in reptiles/avian are called

A

thrombocytes

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26
Q

what dog breeds normally have a low platelet count and can be mislabeled as thrombocytopenia

A

cavalier king charles spaniels (hereditary macrothrombocytopenia)
greyhounds
norfolk terriers
maltese

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27
Q

severe thrombocytopenia in most breeds is

A
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28
Q

what do you need to worry about with a p that has severe (

A

spontaneous bleeding/hemorrhage

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29
Q

what can cause severe thrombocytopenia

A

marrow dz, destruction

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30
Q

what can cause mild and moderate thrombocytopenia

A

marrow dz or consumption

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31
Q

clinical signs of severe thrombocytopenia are associated with

A

SC and mucosal bleeding (petechiation, purpura, ecchymosis, epistaxis, gingival bleeding, melena, hematemesis/uria) and prolonged bleeding after trauma (blood draw)

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32
Q

if a patient has severe thrombocytopenia can you draw blood

A

yes, but do it from small vessels and hold off for longer than normal. Do not do other invasive procedures (cystocentisis) and put them somewhere atraumatic/ can’t bump or injury

How well did you know this?
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33
Q

3 signs of peripheral (outside marrow) thrombocytopenia

A
  1. increased DESTRUCTION
  2. increased CONSUMPTION
  3. abnormal DISTRIBUTION
How well did you know this?
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34
Q

If there is a problem in the marrow causing thrombocytopenia what might you see

A

decreased PRODUCTION

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35
Q

If there is thrombocytopenia with decreased production what might you see in other cells

A

other cell lines involved

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36
Q

5 things that cause decreased production of platelets

A
  1. immune mediated or idiopathic
  2. marrow replacement (neoplasia or fibrosis)
  3. infectious dz
  4. drugs and toxicities (bracken fern)
  5. radiation
How well did you know this?
1
Not at all
2
3
4
5
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37
Q

with thrombocytopenia how would you expect normal BM to repsond

A

Hyperplasia of megakaryocytes (but wit decreased production there is reduced or abscent megakaryocytes)

How well did you know this?
1
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2
3
4
5
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38
Q

other abnormalities depending on underlying cause for decreased production of platelets

A
  1. other cell lines decreased too
  2. morphological abnormalities
  3. abnormal cells in circulation (neoplasia, fibrosis)
How well did you know this?
1
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2
3
4
5
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39
Q

most common ddx for anemia is

A

primary idiopathic

How well did you know this?
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2
3
4
5
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40
Q

most common ddx for thrombocytopenia is

A

secondary immune-mediated (opposite of anemia)

How well did you know this?
1
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2
3
4
5
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41
Q

increased destruction is caused by

A
  1. sulfa antibiotics
  2. vaccination (modified live)
  3. circulating immune complexes (virus, sepsis, neoplasia)
  4. anaplasma platys (infects platelets)
How well did you know this?
1
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2
3
4
5
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42
Q

if give a modified live vaccine how long should you wait before doing anything traumatic to that animal such as surgery

A

2 weeks (thrombocytopenia occurs 3-10days post vx)

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43
Q

if there is increased destruction the platelets will be

A

severely decreased,

How well did you know this?
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2
3
4
5
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44
Q

with increased destruction outside the marrow the __ may increase

A

MPV (mean platelet volume)

How well did you know this?
1
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2
3
4
5
Perfectly
45
Q

what is the first test you should preform with a thrombocytopenia p

A

snap test for tick and mosquito born dz

46
Q

__ the platelets are becoming excessively activated due to increased hemostatic activity (platlete agregation and coagulation)

A

consumption

47
Q

Increased consumption causing thrombocytopenia can cause __, a widepread, uncontrolled activation of coagulation cascade

A

DIC (disseminated intravascular coagulation)

48
Q

4 things that cause increased consumption resulting in thrombocytopenia

A
  1. DIC
  2. microangiopathic dz (hemangiosarc)
  3. vasculitis or endocarditis
  4. envenomations
49
Q

__ alone usually does not result in significant thrombocytopenia

A

blood loss (should NOT be on differential list!)

50
Q

Secondary thrombocytosis (increased platelets) can be caused by

A
  1. Fe def anemia
  2. cushing’s dz
  3. chronic inflammation
  4. post-spenecotmy
  5. vinca alkaloids
  6. rebound from acute hemorrhage
51
Q

__ is abnormal platelet function, there are platelets but they don’t function correctly (it’s similar to having thrombocytopenia)

A

thrombopathia

52
Q

if thrombopathia or thrombocytopenia are suspected what test should you do

A

check blood film for platelet #s

53
Q

after checking blood film with suspected thrombopathia or thrombocytopenia what next

A

test coagulation factors (before doing bleeding test like BMBT)

54
Q

After blood film and coagulation factors have been tested for thrombopathia what next

A

Buccal mucosal bleeding test (BMBT) - Measures the primary hemostatic platelet plug formation time

55
Q

If BMBT is greater than 4 mins what are your concerns

A

thrombocytopenia, platelet defect (thrombopathia), vascular defect

56
Q

what can cause abnormal platelet function (thrombopathia)

A
  1. increased fibrin degradation products inhibit platelet (DIC, fibrionlysis dz)
  2. Drugs (NSAIDS)
  3. Renal failure
  4. hyperglobulinemia
  5. immune mediated thrombocytopenia somtimes
  6. congenital cause (von willebrand’s dz)
57
Q

what is the most common congenital dz (causes thrombopathy)

A

von willebrand’s dz

58
Q

platelets form an initial unstable platelet plug also during __

A

primary hemostasis

59
Q

__ form definitive hemostatic plug in secondary hemostasis by making a stable fibrin clot

A

coagulation factors

60
Q

Sites of extramedullary hematopoeisis where platelets may arise

A
  1. lungs
  2. spleen
  3. liver
61
Q

__ are the precursors to platelet cells

A

megakaryocytes

62
Q

4 factors that can contribute to abnormal platelet concentrations

A

production
consumption
destruction
redistribution (shifting of platelets to/from circuation)

63
Q

most platelet production occurs in the

A

BM

64
Q

__ is when platelets are removed from circulation during normal maintenance or during accelerated states such as thrombotic dz and vasculitis

A

consuption

65
Q

Destruction of platelets occurs by macrophages in the __ and __

A

spleen and liver

66
Q

platelets can sequester in the __ and this redistribution may reduce circulating platelet mass, contraction may increase it

A

spleen

67
Q

explain the 4 steps of primary hemostasis (platelet “bricks”)

A
  1. adhesion
  2. shape change
  3. granule release
  4. aggregation
68
Q

4 things found in platelet DENSE granules that are released after binding which activate more platelets

A
  1. ADP
  2. ATP
  3. Serotonin
  4. Ca++
69
Q

3 things found in platelet ALPHA granules

A
  1. adhesion proteins - von willebrand factor
  2. growth factors
  3. coagulation proteins
70
Q

platelets have what types of granules

A

dense and alpha - contain different things

71
Q

What granules contain von willebrand’s factors

A

alpha granules

72
Q

__ stimulates megakaryocyte and platelet production

A

thrombopoeitin

73
Q

what is the most useful ddx/gold standard for evaluating platelets

A

peripheral blood film! estimate #, look for clumps, observe morphology (megaplatelet, degranulated?)

74
Q

challenging to get accurate platelet counts in __ and __

A

cats (large and clumpy)

horses (clump in EDTA, use citrate)

75
Q

Platelet indicies are similar to RBC indicies

A

MPV, PDW, PCT, MPC (mean platelet content)

76
Q

how do you evaluate megakaryocyte number

A

BM cytology

77
Q

cat platletes

A

larger with higher MPV (mean platelet volume)

sensitive to activation (clumping, degranulate)

78
Q

Platelets are estimated on 100x in the __, to estimate platelets use formula

A

monolayer

estimated platelet count/mcL = average count in 10 fields x 20,000

79
Q

average amount of platelets on 100x field for dogs/cats __, horses __

A

8-12/field

6/field

80
Q

platelets in reptiles/avian are called

A

thrombocytes

81
Q

what dog breeds normally have a low platelet count and can be mislabeled as thrombocytopenia

A

cavalier king charles spaniels (hereditary macrothrombocytopenia)
greyhounds
norfolk terriers
maltese

82
Q

severe thrombocytopenia in most breeds is

A
83
Q

what do you need to worry about with a p that has severe (

A

spontaneous bleeding/hemorrhage

84
Q

what can cause severe thrombocytopenia

A

marrow dz, destruction

85
Q

what can cause mild and moderate thrombocytopenia

A

marrow dz or consumption

86
Q

clinical signs of severe thrombocytopenia are associated with

A

SC and mucosal bleeding (petechiation, purpura, ecchymosis, epistaxis, gingival bleeding, melena, hematemesis/uria) and prolonged bleeding after trauma (blood draw)

87
Q

if a patient has severe thrombocytopenia can you draw blood

A

yes, but do it from small vessels and hold off for longer than normal. Do not do other invasive procedures (cystocentisis) and put them somewhere atraumatic/ can’t bump or injury

88
Q

3 signs of peripheral (outside marrow) thrombocytopenia

A
  1. increased DESTRUCTION
  2. increased CONSUMPTION
  3. abnormal DISTRIBUTION
89
Q

If there is a problem in the marrow causing thrombocytopenia what might you see

A

decreased PRODUCTION

90
Q

If there is thrombocytopenia with decreased production what might you see in other cells

A

other cell lines involved

91
Q

5 things that cause decreased production of platelets

A
  1. immune mediated or idiopathic
  2. marrow replacement (neoplasia or fibrosis)
  3. infectious dz
  4. drugs and toxicities (bracken fern)
  5. radiation
92
Q

with thrombocytopenia how would you expect normal BM to repsond

A

Hyperplasia of megakaryocytes (but wit decreased production there is reduced or abscent megakaryocytes)

93
Q

other abnormalities depending on underlying cause for decreased production of platelets

A
  1. other cell lines decreased too
  2. morphological abnormalities
  3. abnormal cells in circulation (neoplasia, fibrosis)
94
Q

most common ddx for anemia is

A

primary idiopathic

95
Q

most common ddx for thrombocytopenia is

A

secondary immune-mediated (opposite of anemia)

96
Q

increased destruction is caused by

A
  1. sulfa antibiotics
  2. vaccination (modified live)
  3. circulating immune complexes (virus, sepsis, neoplasia)
  4. anaplasma platys (infects platelets)
97
Q

if give a modified live vaccine how long should you wait before doing anything traumatic to that animal such as surgery

A

2 weeks (thrombocytopenia occurs 3-10days post vx)

98
Q

if there is increased destruction the platelets will be

A

severely decreased,

99
Q

with increased destruction outside the marrow the __ may increase

A

MPV (mean platelet volume)

100
Q

what is the first test you should preform with a thrombocytopenia p

A

snap test for tick and mosquito born dz

101
Q

__ the platelets are becoming excessively activated due to increased hemostatic activity (platlete agregation and coagulation)

A

consumption

102
Q

Increased consumption causing thrombocytopenia can cause __, a widepread, uncontrolled activation of coagulation cascade

A

DIC (disseminated intravascular coagulation)

103
Q

4 things that cause increased consumption resulting in thrombocytopenia

A
  1. DIC
  2. microangiopathic dz (hemangiosarc)
  3. vasculitis or endocarditis
  4. envenomations
104
Q

__ alone usually does not result in significant thrombocytopenia

A

blood loss (should NOT be on differential list!)

105
Q

Secondary thrombocytosis (increased platelets) can be caused by

A
  1. Fe def anemia
  2. cushing’s dz
  3. chronic inflammation
  4. post-spenecotmy
  5. vinca alkaloids
  6. rebound from acute hemorrhage
106
Q

__ is abnormal platelet function, there are platelets but they don’t function correctly (it’s similar to having thrombocytopenia)

A

thrombopathia

107
Q

if thrombopathia or thrombocytopenia are suspected what test should you do

A

check blood film for platelet #s

108
Q

after checking blood film with suspected thrombopathia or thrombocytopenia what next

A

test coagulation factors (before doing bleeding test like BMBT)

109
Q

After blood film and coagulation factors have been tested for thrombopathia what next

A

Buccal mucosal bleeding test (BMBT) - Measures the primary hemostatic platelet plug formation time

110
Q

If BMBT is greater than 4 mins what are your concerns

A

thrombocytopenia, platelet defect (thrombopathia), vascular defect

111
Q

what can cause abnormal platelet function (thrombopathia)

A
  1. increased fibrin degradation products inhibit platelet (DIC, fibrionlysis dz)
  2. Drugs (NSAIDS)
  3. Renal failure
  4. hyperglobulinemia
  5. immune mediated thrombocytopenia somtimes
  6. congenital cause (von willebrand’s dz)
112
Q

what is the most common congenital dz (causes thrombopathy)

A

von willebrand’s dz

Clinical Pathology Exam 1 (12 decks)

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