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Clinical Pathology > UNIT 1 - Lecture 13: Coagulation > Flashcards

UNIT 1 - Lecture 13: Coagulation Flashcards

1
Q

Prolongation of what 2 coagulation values are common if samples are not properly collected?

A

PT and aPTT

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2
Q

What does ACT stand for?

A

Activated Coagulation Time

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3
Q

ACT is a modified _____.

A

APTT

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4
Q

What two pathways does ACT screen?

A

Intrinsic and common

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5
Q

How sensitive is ACT compared to APTT?

A

less sensitive (factor activity needs to be <10% of normal)

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6
Q

What is a common contact activator for ACT?

A

diatomaceous earth

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7
Q

What 2 things does ACT require?

A

Platelets and Ca2+ to support reaction;

So values are impacted by severe thrombocytopenia (<10,000/µL)

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8
Q

What factors make up the intrinsic pathway in the coagulation cascade?

A

XII, XI, IX, VIII

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9
Q

What factors make up the common pathway of the coagulation cascade?

A

X

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10
Q

What does APTT stand for?

A

Activated partial Thromboplastin Time

(AKA PTT)

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11
Q

What pathways are screened by APTT?

A

Intrinsic and common

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12
Q

What does APTT measure?

A

Time to fibrin clot formation in citrated plasma after addition of contact activator, phospholipid, and calcium

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13
Q

T/F: APTT requires platient platelets

A

False

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14
Q

Factor activity in APTT must be ___% of normal for prolongation.

A

<30%

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15
Q

What does PT stand for?

A

Prothrombin Time

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16
Q

What pathways are screened in PT?

A

Extrinsic and common

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17
Q

What factor is involved in the extrinsic pathway of the coagulation cascade?

A

VII

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18
Q

PT times are considered prolonged when factor activities are ___%.

A

<30%

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19
Q

T/F: PT does not require patient platelets

A

True

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20
Q

What is PT a sensitive indicator of and why?

A

Vitamin K antagonist rodenticide toxicity;

Factor VII is the Vit K-dependent factor with the shortest half life –> PT screens the extrinsic pathway which involves factor VII

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21
Q

What factor is the Vit K-dependent factor with the shortest half-life?

A

VII

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22
Q

What do TT and TCT stand for?

A

TT = Thrombin Time

TCT = Thrombin Clot Time

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23
Q

TT and TCT directly measure ____.

A

functional fibrinogen

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24
Q

What specifically do TT and TCT measure?

A

Time (sec) required for fibrin clot formation to occur in citrated plasma after addition of thrombin and calcium

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25
In regards to TT and TCT, rate of clot formation is proportional to functional \_\_\_\_\_.
fibrinogen concentration
26
What is low fibrinogen usually the result of and what is an example?
Usually result of consumption (i.e. DIC)
27
What is another name for PIVKA?
thrombotest
28
What does PIVKA evaluate?
Proteins induced by vit K absence/antagonism
29
How is a prolonged PIVKA test interpreted?
Test is prolonged when proteins are not activated in the presence of vit K antagonists or with vit K deficiency; It is increased with Vit K deficiency/antagonism
30
What are FDPs?
Fibrin Degradation Products: Circulating fragments of fibrinogen or soluble fibrin
31
How do FDPs form?
From plasmin-mediated breakdown of fibrinogen OR fibrin
32
What 4 things can increased FDPs be seen with?
1. DIC (increased production) 2. Bleeding/thrombosis (increased production) 3. Inflammation (increased production) 4. Severe liver disease (decreased clearance by liver)
33
What are D-Dimers and how are they produced?
Fairly specific indicator of secondary fibrinolysis (clot breakdown); Produced via plasmin-mediated degradation of cross-linked fibrin
34
When are increased D-Dimers seen?
Thrombosis and fibrinolysis: 1. DIC 2. Surgery 3. Thromboembolism
35
When is fibrinogen increased?
with inflammation
36
When is fibrinogen decreased?
1. Massive activation of coagulation (DIC, clotting) 2. Liver failure (decreased production)
37
What do AT and ATIII stand for?
Antithrombin and Antithrombin III
38
AT and ATIII interact with _____ to inactivate _____ and others.
heparin, thrombin
39
What things can decrease AT?
1. Increased consumption (DIC) 2. Decreased production (liver dysfunction, infflammation) 3. Increased loss (protein-losing nephropathy or enteropathy)
40
Patients with decreased AT are at greater risk for \_\_\_\_\_.
thrombosis
41
What is the most common heritable factor deficiency in domestic animals?
Hemophilia A
42
What factor is decifient in Hemophilia A?
Factor VIII
43
What sex is affected by Hemophilia A?
Males (XY) - it is an X-linked recessive trait
44
What coag values are abnormal with Hemophilia A?
Prolonged APTT and ACT
45
What spp can get Hemophilia A?
Dogs, cats, horses, Hereford cattle
46
What factor is deficient in Hemophilia B?
Factor IX
47
What sex is affected by Hemophilia B?
Males (XY)
48
What is the 2nd most common inherited coag disorder?
Hemophilia B
49
What spp get Hemophilia B?
Dogs (Shepherds, Labs), and rare in cats
50
What test results are abnormal with Hemophilia B?
Prolonged APTT and ACT
51
What factor is deficient in Hageman's Disease?
Factor XII
52
Hageman's disease is not associated with \_\_\_\_\_.
bleeding
53
What test values are associated with Hageman's Disease?
1. Prolonged APTT 2. Prolonged ACT 3. *Normal* PT
54
What spp is Hageman's Disease mostly described in?
cats
55
How frequently do we see inherited Vit K deficiency?
rarely
56
What is the most common cause of Vit K-dependent coagulopathy?
Vit K antagonism
57
How long after exposure does bleeding from Vit K antagonism occur?
3-7 days
58
What are 2 causes for Vit K antagonism?
1. **Anticoagulant rodenticide toxicosis** 2. Moldy sweet clover (cattle)
59
What factors are antagonized by rodenticides?
Vit K dependent: X, IX, VII, II, protein C, protein S
60
What test results are consistent with anticoagulant rodenticide poisoning?
1. Low platelets if hemorrhage 2. APTT prolonged 3. PT prolonged
61
What coagulation factors and inhibitors would have decreased production with liver failure?
Vit K factors, fibrinogen, Factor VIII, protein C, protein S, AT
62
Liver failure leads to decreased activation of _____ enzymes.
Vit K-dependent
63
Liver failure leads to decreased clearance of _____ & \_\_\_\_\_.
FDPs, D-Dimers
64
Liver failure leads to increased risk of secondary \_\_\_\_\_.
DIC
65
What is the main cause for DIC?
Massive actication of coagulation that is regionally or disseminated throughout the body, such as widespread tissue damage or neoplasia.
66
What does DIC result in?
Diffuse thrombosis (microvasculature) --\> massive consumption of plts and coag factors --\> hemorrhage due to lack of plts and factors
67
What is compensated (non-overt) DIC?
Activated but not overwhelmed hemostasis; thrombin is generated and patient still has enough inhibitors of coagulation to keep system in check
68
What is uncompensated (fulminant, overt) DIC?
Clinical signs point to thrombosis and hemorrhage; inhibitors of coagulation are overwhelmed, there is high morbidity/mortality, and test results are abnormal
69
What are some test results that will be abnormal when DIC is occurring?
1. Prolonged PT 2. Prolonged APTT 3. Increased D-Dimer 4. Increased FDP 5. Decreased fibrinogen 6. Decreased AT 7. Thrombocytopenia 8. RBC fragments (schistocytes)
70
**In DIC:** * Plt count = \_\_\_\_\_ * BMBT = \_\_\_\_\_ * APTT = \_\_\_\_\_ * PT = \_\_\_\_\_ * TT = \_\_\_\_\_ * FDP = \_\_\_\_\_
* Plt count = decreased * BMBT = increased * APTT = increased * PT = increased * TT = increased * FDP = increased
71
**In thrombocytopenia:** * Plt count = \_\_\_\_\_ * BMBT = \_\_\_\_\_ * APTT = \_\_\_\_\_ * PT = \_\_\_\_\_ * TT = \_\_\_\_\_ * FDP = \_\_\_\_\_
* Plt count = decreased * BMBT = increased * APTT = WRI * PT = WRI * TT = WRI * FDP = WRI
72
**In Von Willebrand's:** * Plt count = \_\_\_\_\_ * BMBT = \_\_\_\_\_ * APTT = \_\_\_\_\_ * PT = \_\_\_\_\_ * TT = \_\_\_\_\_ * FDP = \_\_\_\_\_
* Plt count = WRI * BMBT = increased * APTT = WRI * PT = WRI * TT = WRI * FDP = WRI
73
**In anticoagulant rodenticide poisoning, liver disease, or bile insufficiency:** * Plt count = \_\_\_\_\_ * BMBT = \_\_\_\_\_ * APTT = \_\_\_\_\_ * PT = \_\_\_\_\_ * TT = \_\_\_\_\_ * FDP = \_\_\_\_\_
* Plt count = WRI * BMBT = WRI * APTT = Increased * PT = Increased * TT = WRI * FDP = WRI
74
What is the most common inherited disease od primary hemostasis? Secodary?
Primary = von Willebrand's Secondary = Hemophilias (A\>B)
75
What are the 3 most common coagulopathies?
1. Thrombocytopenia (primary) 2. DIC (primary, secondary, tertiary) 3. Rodenticide toxicosis (secondary)

Clinical Pathology (22 decks)

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