Coagulation Testing Flashcards

1
Q

What is hemostatsis the balance between?

A
  • The bodies need to respond to injury by preventing hemorrhage by initiating thrombosis
  • Maintaining effective circulation
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2
Q

What are the 3 components of hemostasis

A
  1. Vessel wall
  2. Platelets
  3. Coagulation system
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3
Q

What carries out primary hemostasis

A

Platelets

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4
Q

What are the components of primary hemostasis

A
  • Adhesion of collagen to the site of vascular injury
  • Adhesion of other platelets
  • Release of platelet contents to promote platelet aggregation
  • Provision of a phospholipid surface to assemble proteins of the coagulation cascade
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5
Q

What are examples of platelet contents?

A
  • ADP
  • ATP
  • Calcium clotting factors
  • Thromboxane A
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6
Q

Why is the phospholipid surface so important?

A

-Crucial for organizing and promoting interactions of clotting factors

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7
Q

What carries out secondary hemostasis?

A

The coagulation system

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8
Q

_______ circulate until they are activated

A

Proenzymes

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9
Q

What is the coagulation cascade divided into?

A
  1. Extrinsic
  2. Intrinsic
  3. Common
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10
Q

Are these cascades separate, or work in conjunction with each other?

A

Work in conjunction with eachother

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11
Q

Why are the pathways useful?

A
  • Understanding in vitro lab tests

- Identifying specific factor deficiencies

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12
Q

Disruption of the endothelium results in the exposure of…

A

Tissue factor (thromboplastin) in subendothelial tissue

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13
Q

Exposure of tissue factor results in the ______ pathway

A

Extrinsic

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14
Q

How is the extrinsic pathway triggered?

A

Converting Factor 7 to 7a

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15
Q

The endothelial disruption also exposes ______ in the vascular wall

A

Collagen

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16
Q

The exposure of collagen results in the activation of ______________ in the _______ pathway

A

-Contact phase proteins in the intrinsic pathway

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17
Q

Contact phase enzymes are also called…

A

Proenzymes

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18
Q

T/F- Triggering of the extrinsic and intrinsic pathways occur simultaneously

A

True

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19
Q

What are the 2 activators of the coagulation cascade?

A
  • Tissue Factor (extrinsic)

- Contact phase proteins (intrinsic)

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20
Q

What are 3 examples of contact phase proteins?

A
  • High molecular weight kininogen
  • Kallikrein
  • Factor 12 (hagpan factor)
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21
Q

What are the 4 Vitamin K dependent factors?

A

2, 7, 9, 10

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22
Q

Where are vitamin K dependent factors formed?

A

Liver

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23
Q

What do factors 2, 7, 9, 10 require as a cofactor for optimal activity of the clotting cascade?

A

Vitamin K

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24
Q

What synthesizes Vitamin K

A

Normal flora of the GI tract

-or obtained in diet from leafy green veggies

25
Q

What are 3 causes of Vitamin K deficiency

A
  • Malnutrition
  • Broad spectrum antibiotics (disrupt normal flora)
  • Coumadin (inhibits vitamin K factors
26
Q

What are the cofactors?

A

7a and 5a

27
Q

What happens if you do not have the correct cofactors

A

Factors 9 and 10 have reduced activity and clotting is impaired

28
Q

The conversion of ______ to _____ produces a soft clot

A

Fibrinogen to fibrin

29
Q

What factor stabilizes the soft clot

A

Factor 13

30
Q

What happens if you have a deficiency in inhibitors of coagulation?

A

You get a hypercoagulable state

31
Q

Hypercoagulatible states increase the incidence of _______

A

Thrombotic events

32
Q

What are examples of thrombotic events

A
  • DVT/PE
  • CVA
  • MI
33
Q

____________ in the presence of fibrin and components of contact phase convert circulating plasminogen into plasmin

A

Tissue plasminogen activator (tPA)

34
Q

What is the active enzyme of plasminogen?

A

Plasmin

35
Q

Plasmin degrades…

A

Fibrin

36
Q

This is a naturally occurring anticoagulant in the presence of tissue heparin or exogenous heparin

A

Antithromin 3

37
Q

What is the function of antithrombin 3

A

-Heparin complex that inhibits the enzyme activity of factor 2a (thrombin), 4a, and 5a

38
Q

When this protein is activates, it is an enzyme that cleaves and destroys the factors 13a and 10a

A

Protein C

39
Q

This is a cofactor for protein C

A

Protein S

40
Q

Will protein C be effected by vitamin K deficiency?

A

Yes- because protein C is a vitamin K dependent enzyme and will be effected by vitamin K defieciency or Coumadin therapy

41
Q

This is a coag. test that tests the…

  • Extrinsic pathway
  • Common pathway
A

Protrombin time (PT/INR)

42
Q

How do you test PT?

A
  • Take a sample of plasma
  • Add tissue factor and calcium
  • Measure the time it takes fibrin to form a clot
43
Q

Does Coumadin effect PT?

A

Yes

extrinsic, Coumadin is given OUTpateint

44
Q

What is tissue factor derieved from that it can have great variability in the results of the PT

A

Biological factors

45
Q

To reduce variability, PT is converted to…

A

International normalized ratio (INR)

46
Q

What is a normal INR for a healthy patient?

A

1.0

47
Q

The higher the INR, the thinner/thicker the blood

A

Thinner

48
Q

What is an example when an elevated PT/INR (normal PTT) are seen?

A
  • Vitamin K deficiency
  • Coumadin therapy
  • Liver disease
49
Q

What does activated partial thromboplastin measure?

A

Intrinsic clotting pathway

50
Q

How do you test PTT

A
  • Take plasma sample
  • Add calcium and contact phase activator
  • Results are recorded by the amount of time it takes fibrin to clot
51
Q

When is elevated PTT seen?

A

-Heparin therapy

52
Q

When are fibrinogen levels used?

A

-IN hypercoagulatible state workups

53
Q

How do you test fibrinogen levels?

A

-Adding bovine thrombin to a sample of plasma

54
Q

In most cases, determining the status of Protein C, protein S, and antithrombin levels will be low yield and not cost effective

A

True

55
Q

Factor 5 Lieden results from a single amino acid mutation of factor 5. What does this cause?

A
  • Hypercoagulatible state

- found more commonly in PE and DVT patients

56
Q

What are additional tests for hypercoagulatibity work up?

A
  • Homocysteine levels
  • Lupus anticoagulant levels
  • Malignancy workup
57
Q

What increases the risk for hypercoagulable states?

A
  • Oral contraceptives

- Smoking

58
Q

What causes abnormal coagulation test results?

A
  • Incompletely filled collection tube
  • Heparin contamination
  • Blood draws from catheters which are coated in hepatrin
  • Blood draws in close proximity to lines infusing heparin