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Flashcards in Coagulation Testing Deck (58):
1

What is hemostatsis the balance between?

-The bodies need to respond to injury by preventing hemorrhage by initiating thrombosis
-Maintaining effective circulation

2

What are the 3 components of hemostasis

1. Vessel wall
2. Platelets
3. Coagulation system

3

What carries out primary hemostasis

Platelets

4

What are the components of primary hemostasis

-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

5

What are examples of platelet contents?

-ADP
-ATP
-Calcium clotting factors
-Thromboxane A

6

Why is the phospholipid surface so important?

-Crucial for organizing and promoting interactions of clotting factors

7

What carries out secondary hemostasis?

The coagulation system

8

_______ circulate until they are activated

Proenzymes

9

What is the coagulation cascade divided into?

1. Extrinsic
2. Intrinsic
3. Common

10

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

Work in conjunction with eachother

11

Why are the pathways useful?

-Understanding in vitro lab tests
-Identifying specific factor deficiencies

12

Disruption of the endothelium results in the exposure of...

Tissue factor (thromboplastin) in subendothelial tissue

13

Exposure of tissue factor results in the ______ pathway

Extrinsic

14

How is the extrinsic pathway triggered?

Converting Factor 7 to 7a

15

The endothelial disruption also exposes ______ in the vascular wall

Collagen

16

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

-Contact phase proteins in the intrinsic pathway

17

Contact phase enzymes are also called...

Proenzymes

18

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

True

19

What are the 2 activators of the coagulation cascade?

-Tissue Factor (extrinsic)
-Contact phase proteins (intrinsic)

20

What are 3 examples of contact phase proteins?

-High molecular weight kininogen
-Kallikrein
-Factor 12 (hagpan factor)

21

What are the 4 Vitamin K dependent factors?

2, 7, 9, 10

22

Where are vitamin K dependent factors formed?

Liver

23

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

Vitamin K

24

What synthesizes Vitamin K

Normal flora of the GI tract
-or obtained in diet from leafy green veggies

25

What are 3 causes of Vitamin K deficiency

-Malnutrition
-Broad spectrum antibiotics (disrupt normal flora)
-Coumadin (inhibits vitamin K factors

26

What are the cofactors?

7a and 5a

27

What happens if you do not have the correct cofactors

Factors 9 and 10 have reduced activity and clotting is impaired

28

The conversion of ______ to _____ produces a soft clot

Fibrinogen to fibrin

29

What factor stabilizes the soft clot

Factor 13

30

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

You get a hypercoagulable state

31

Hypercoagulatible states increase the incidence of _______

Thrombotic events

32

What are examples of thrombotic events

-DVT/PE
-CVA
-MI

33

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

Tissue plasminogen activator (tPA)

34

What is the active enzyme of plasminogen?

Plasmin

35

Plasmin degrades...

Fibrin

36

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

Antithromin 3

37

What is the function of antithrombin 3

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

38

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

Protein C

39

This is a cofactor for protein C

Protein S

40

Will protein C be effected by vitamin K deficiency?

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

41

This is a coag. test that tests the...
-Extrinsic pathway
-Common pathway

Protrombin time (PT/INR)

42

How do you test PT?

-Take a sample of plasma
-Add tissue factor and calcium
-Measure the time it takes fibrin to form a clot

43

Does Coumadin effect PT?

Yes
(extrinsic, Coumadin is given OUTpateint)

44

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

Biological factors

45

To reduce variability, PT is converted to...

International normalized ratio (INR)

46

What is a normal INR for a healthy patient?

1.0

47

The higher the INR, the thinner/thicker the blood

Thinner

48

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

-Vitamin K deficiency
-Coumadin therapy
-Liver disease

49

What does activated partial thromboplastin measure?

Intrinsic clotting pathway

50

How do you test PTT

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

51

When is elevated PTT seen?

-Heparin therapy

52

When are fibrinogen levels used?

-IN hypercoagulatible state workups

53

How do you test fibrinogen levels?

-Adding bovine thrombin to a sample of plasma

54

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

True

55

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

-Hypercoagulatible state
-found more commonly in PE and DVT patients

56

What are additional tests for hypercoagulatibity work up?

-Homocysteine levels
-Lupus anticoagulant levels
-Malignancy workup

57

What increases the risk for hypercoagulable states?

-Oral contraceptives
-Smoking

58

What causes abnormal coagulation test results?

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