Coagulation Testing

Question 1

What is hemostatsis the balance between?

Answer 1

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

Question 2

What are the 3 components of hemostasis

Answer 2

1. Vessel wall
2. Platelets
3. Coagulation system

Question 3

What carries out primary hemostasis

Answer 3

Platelets

Question 4

What are the components of primary hemostasis

Answer 4

• 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

Question 5

What are examples of platelet contents?

Answer 5

• ADP
• ATP
• Calcium clotting factors
• Thromboxane A

Question 6

Why is the phospholipid surface so important?

Answer 6

-Crucial for organizing and promoting interactions of clotting factors

Question 7

What carries out secondary hemostasis?

Answer 7

The coagulation system

Question 8

_______ circulate until they are activated

Answer 8

Proenzymes

Question 9

What is the coagulation cascade divided into?

Answer 9

1. Extrinsic
2. Intrinsic
3. Common

Question 10

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

Answer 10

Work in conjunction with eachother

Question 11

Why are the pathways useful?

Answer 11

• Understanding in vitro lab tests

- Identifying specific factor deficiencies

Question 12

Disruption of the endothelium results in the exposure of…

Answer 12

Tissue factor (thromboplastin) in subendothelial tissue

Question 13

Exposure of tissue factor results in the ______ pathway

Answer 13

Extrinsic

Question 14

How is the extrinsic pathway triggered?

Answer 14

Converting Factor 7 to 7a

Question 15

The endothelial disruption also exposes ______ in the vascular wall

Answer 15

Collagen

Question 16

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

Answer 16

-Contact phase proteins in the intrinsic pathway

Question 17

Contact phase enzymes are also called…

Answer 17

Proenzymes

Question 18

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

Answer 18

True

Question 19

What are the 2 activators of the coagulation cascade?

Answer 19

• Tissue Factor (extrinsic)

- Contact phase proteins (intrinsic)

Question 20

What are 3 examples of contact phase proteins?

Answer 20

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

Question 21

What are the 4 Vitamin K dependent factors?

Answer 21

2, 7, 9, 10

Question 22

Where are vitamin K dependent factors formed?

Answer 22

Liver

Question 23

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

Answer 23

Vitamin K

Question 24

What synthesizes Vitamin K

Answer 24

Normal flora of the GI tract

-or obtained in diet from leafy green veggies

Question 25

What are 3 causes of Vitamin K deficiency

Answer 25

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

Question 26

What are the cofactors?

Answer 26

7a and 5a

Question 27

What happens if you do not have the correct cofactors

Answer 27

Factors 9 and 10 have reduced activity and clotting is impaired

Question 28

The conversion of ______ to _____ produces a soft clot

Answer 28

Fibrinogen to fibrin

Question 29

What factor stabilizes the soft clot

Answer 29

Factor 13

Question 30

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

Answer 30

You get a hypercoagulable state

Question 31

Hypercoagulatible states increase the incidence of _______

Answer 31

Thrombotic events

Question 32

What are examples of thrombotic events

Answer 32

- DVT/PE - CVA - MI

Question 33

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

Answer 33

Tissue plasminogen activator (tPA)

Question 34

What is the active enzyme of plasminogen?

Answer 34

Plasmin

Question 35

Plasmin degrades...

Answer 35

Fibrin

Question 36

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

Answer 36

Antithromin 3

Question 37

What is the function of antithrombin 3

Answer 37

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

Question 38

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

Answer 38

Protein C

Question 39

This is a cofactor for protein C

Answer 39

Protein S

Question 40

Will protein C be effected by vitamin K deficiency?

Answer 40

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

Question 41

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

Answer 41

Protrombin time (PT/INR)

Question 42

How do you test PT?

Answer 42

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

Question 43

Does Coumadin effect PT?

Answer 43

Yes | extrinsic, Coumadin is given OUTpateint

Question 44

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

Answer 44

Biological factors

Question 45

To reduce variability, PT is converted to...

Answer 45

International normalized ratio (INR)

Question 46

What is a normal INR for a healthy patient?

Answer 46

1.0

Question 47

The higher the INR, the thinner/thicker the blood

Answer 47

Thinner

Question 48

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

Answer 48

- Vitamin K deficiency - Coumadin therapy - Liver disease

Question 49

What does activated partial thromboplastin measure?

Answer 49

Intrinsic clotting pathway

Question 50

How do you test PTT

Answer 50

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

Question 51

When is elevated PTT seen?

Answer 51

-Heparin therapy

Question 52

When are fibrinogen levels used?

Answer 52

-IN hypercoagulatible state workups

Question 53

How do you test fibrinogen levels?

Answer 53

-Adding bovine thrombin to a sample of plasma

Question 54

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

Answer 54

True

Question 55

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

Answer 55

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

Question 56

What are additional tests for hypercoagulatibity work up?

Answer 56

- Homocysteine levels - Lupus anticoagulant levels - Malignancy workup

Question 57

What increases the risk for hypercoagulable states?

Answer 57

- Oral contraceptives | - Smoking

Question 58

What causes abnormal coagulation test results?

Answer 58

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