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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
Q

In regards to TT and TCT, rate of clot formation is proportional to functional _____.

A

fibrinogen concentration

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26
Q

What is low fibrinogen usually the result of and what is an example?

A

Usually result of consumption (i.e. DIC)

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27
Q

What is another name for PIVKA?

A

thrombotest

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28
Q

What does PIVKA evaluate?

A

Proteins induced by vit K absence/antagonism

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29
Q

How is a prolonged PIVKA test interpreted?

A

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

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30
Q

What are FDPs?

A

Fibrin Degradation Products:

Circulating fragments of fibrinogen or soluble fibrin

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31
Q

How do FDPs form?

A

From plasmin-mediated breakdown of fibrinogen OR fibrin

32
Q

What 4 things can increased FDPs be seen with?

A
  1. DIC (increased production)
  2. Bleeding/thrombosis (increased production)
  3. Inflammation (increased production)
  4. Severe liver disease (decreased clearance by liver)
33
Q

What are D-Dimers and how are they produced?

A

Fairly specific indicator of secondary fibrinolysis (clot breakdown);

Produced via plasmin-mediated degradation of cross-linked fibrin

34
Q

When are increased D-Dimers seen?

A

Thrombosis and fibrinolysis:

  1. DIC
  2. Surgery
  3. Thromboembolism
35
Q

When is fibrinogen increased?

A

with inflammation

36
Q

When is fibrinogen decreased?

A
  1. Massive activation of coagulation (DIC, clotting)
  2. Liver failure (decreased production)
37
Q

What do AT and ATIII stand for?

A

Antithrombin and Antithrombin III

38
Q

AT and ATIII interact with _____ to inactivate _____ and others.

A

heparin, thrombin

39
Q

What things can decrease AT?

A
  1. Increased consumption (DIC)
  2. Decreased production (liver dysfunction, infflammation)
  3. Increased loss (protein-losing nephropathy or enteropathy)
40
Q

Patients with decreased AT are at greater risk for _____.

A

thrombosis

41
Q

What is the most common heritable factor deficiency in domestic animals?

A

Hemophilia A

42
Q

What factor is decifient in Hemophilia A?

A

Factor VIII

43
Q

What sex is affected by Hemophilia A?

A

Males (XY) - it is an X-linked recessive trait

44
Q

What coag values are abnormal with Hemophilia A?

A

Prolonged APTT and ACT

45
Q

What spp can get Hemophilia A?

A

Dogs, cats, horses, Hereford cattle

46
Q

What factor is deficient in Hemophilia B?

A

Factor IX

47
Q

What sex is affected by Hemophilia B?

A

Males (XY)

48
Q

What is the 2nd most common inherited coag disorder?

A

Hemophilia B

49
Q

What spp get Hemophilia B?

A

Dogs (Shepherds, Labs), and rare in cats

50
Q

What test results are abnormal with Hemophilia B?

A

Prolonged APTT and ACT

51
Q

What factor is deficient in Hageman’s Disease?

A

Factor XII

52
Q

Hageman’s disease is not associated with _____.

A

bleeding

53
Q

What test values are associated with Hageman’s Disease?

A
  1. Prolonged APTT
  2. Prolonged ACT
  3. Normal PT
54
Q

What spp is Hageman’s Disease mostly described in?

A

cats

55
Q

How frequently do we see inherited Vit K deficiency?

A

rarely

56
Q

What is the most common cause of Vit K-dependent coagulopathy?

A

Vit K antagonism

57
Q

How long after exposure does bleeding from Vit K antagonism occur?

A

3-7 days

58
Q

What are 2 causes for Vit K antagonism?

A
  1. Anticoagulant rodenticide toxicosis
  2. Moldy sweet clover (cattle)
59
Q

What factors are antagonized by rodenticides?

A

Vit K dependent: X, IX, VII, II, protein C, protein S

60
Q

What test results are consistent with anticoagulant rodenticide poisoning?

A
  1. Low platelets if hemorrhage
  2. APTT prolonged
  3. PT prolonged
61
Q

What coagulation factors and inhibitors would have decreased production with liver failure?

A

Vit K factors, fibrinogen, Factor VIII, protein C, protein S, AT

62
Q

Liver failure leads to decreased activation of _____ enzymes.

A

Vit K-dependent

63
Q

Liver failure leads to decreased clearance of _____ & _____.

A

FDPs, D-Dimers

64
Q

Liver failure leads to increased risk of secondary _____.

A

DIC

65
Q

What is the main cause for DIC?

A

Massive actication of coagulation that is regionally or disseminated throughout the body, such as widespread tissue damage or neoplasia.

66
Q

What does DIC result in?

A

Diffuse thrombosis (microvasculature) –> massive consumption of plts and coag factors –> hemorrhage due to lack of plts and factors

67
Q

What is compensated (non-overt) DIC?

A

Activated but not overwhelmed hemostasis; thrombin is generated and patient still has enough inhibitors of coagulation to keep system in check

68
Q

What is uncompensated (fulminant, overt) DIC?

A

Clinical signs point to thrombosis and hemorrhage; inhibitors of coagulation are overwhelmed, there is high morbidity/mortality, and test results are abnormal

69
Q

What are some test results that will be abnormal when DIC is occurring?

A
  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
Q

In DIC:

  • Plt count = _____
  • BMBT = _____
  • APTT = _____
  • PT = _____
  • TT = _____
  • FDP = _____
A
  • Plt count = decreased
  • BMBT = increased
  • APTT = increased
  • PT = increased
  • TT = increased
  • FDP = increased
71
Q

In thrombocytopenia:

  • Plt count = _____
  • BMBT = _____
  • APTT = _____
  • PT = _____
  • TT = _____
  • FDP = _____
A
  • Plt count = decreased
  • BMBT = increased
  • APTT = WRI
  • PT = WRI
  • TT = WRI
  • FDP = WRI
72
Q

In Von Willebrand’s:

  • Plt count = _____
  • BMBT = _____
  • APTT = _____
  • PT = _____
  • TT = _____
  • FDP = _____
A
  • Plt count = WRI
  • BMBT = increased
  • APTT = WRI
  • PT = WRI
  • TT = WRI
  • FDP = WRI
73
Q

In anticoagulant rodenticide poisoning, liver disease, or bile insufficiency:

  • Plt count = _____
  • BMBT = _____
  • APTT = _____
  • PT = _____
  • TT = _____
  • FDP = _____
A
  • Plt count = WRI
  • BMBT = WRI
  • APTT = Increased
  • PT = Increased
  • TT = WRI
  • FDP = WRI
74
Q

What is the most common inherited disease od primary hemostasis? Secodary?

A

Primary = von Willebrand’s

Secondary = Hemophilias (A>B)

75
Q

What are the 3 most common coagulopathies?

A
  1. Thrombocytopenia (primary)
  2. DIC (primary, secondary, tertiary)
  3. Rodenticide toxicosis (secondary)

Clinical Pathology (22 decks)

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