COAGULATION & HEMOSTASIS

Question 1

What coagulation factors does Warfarin/Coumadin inhibit, and what are they dependent on?

Answer 1

It inhibits factors II, VII, IX, and X, these factors are dependent on vitamin K

Question 2

What Causes increases in PT/INR?

Answer 2

• Factor deficiency I, II, V, VII and X
• Warfarin/Coumadin
• Liver Disease
• DIC
• Vitamin K deficiency
• GI disease
• Antibiotics

Question 3

What does Antithrombin III inhibit?

Answer 3

Factors IIa, Xa (most important), IX, XI, XII, also has an inhibitory effect on plasmin and kalikrein

Question 4

What factors does Protein C inhibit?

Answer 4

Va and VIIIa

Question 5

What protein does Thrombin activate?

Answer 5

Protein C

Question 6

What factors are part of the intrinsic pathway?

Answer 6

XII, XI, IX, VIII

Question 6

What factors are measured by the extrinsic pathway?

Answer 6

VII, X, V, II, I

Question 7

What factors are part of the common pathway?

Answer 7

X, V, II, I

Question 8

How will the presence of hemolysis affect coagulation testing?

Answer 8

It will cause falsely shortened results

Question 9

How will the presence of lipemia affect coagulation testing?

Answer 9

May falsely prolong results due to interference with light transmittance

Question 10

How will partially clotted specimens affect coagulation testing?

Answer 10

May cause falsely shortened results due to the activation of factors VIIa and thrombin

Question 11

How will fully clotted specimens affect coagulation testing?

Answer 11

Will give falsely elevated results due to consumption and depletion of coagulation factors. (contain no fibrinogen)

Question 12

What is the proper centrifugation for coagulation testing?

Answer 12

3000rpm at 15min

Question 13

What is the appropriate anticoagulant for coagulation?

Answer 13

3.2% sodium citrate tube

Question 14

How does high hematocrit affect coagulation testing and why?

Answer 14

Falsely elevated results because high Na Citrate interferes with recalcification stage of testing

Question 15

What temperature should PT/INR samples stored at and when do they have to be tested?

Answer 15

Stored at 18-24 C, tested within 24hrs

Question 16

What should APTT samples be stored at and when do they have to be tested?

Answer 16

Stored at 18-24 C, tested within 4hrs provided they do not contain unfractionated heparin, samples containing unfractionated heparin must be centrifuged within a 1hr and tested within 4hrs.

Question 17

Why do unfractionated heparin samples have to be centrifuged within an hour?

Answer 17

To reduce the effect of heparin neutralization by platelet factor 4

Question 18

What is the storage of samples that have platelet-poor plasma (PPP)?

Answer 18

May be frozen at -20 C for up to 2 weeks and at -70 C for 6 months

Question 19

What is the proper way to thaw a coagulation sample?

Answer 19

Rapidly thawed at 37 C to prevent deterioration of factors V and VII, mixed well and tested within an hour.

Question 20

What is a thrombus?

Answer 20

A thrombus is an abnormal function of a platelet or fibrin clot obstruction of a blood vessel, leads to thrombosis

Question 21

What does a positive or high D-Dimer indicate?

Answer 21

In vivo lysis of cross-linked fibrin

Question 22

Which genetic risk factor is the most prevalent in patients with Thrombophilia?

Answer 22

Activated Protein C Resistance (Factor V Leiden)

Question 23

What is the primary function of Protein S?

Answer 23

Functions as a cofactor for Protein C

Question 24

What best describes Heparin-induced thrombocytopenia (HIT)?

Answer 24

Antibodies bind to Heparin/Platelet factor 4 complex

Question 25

What is the most frequent cause of abnormal Primary Hemostasis?

Answer 25

Thrombocytopenia / platelet disorders

Question 26

What is the purpose of the synthetic activator used in the activated partial thromboplastin time test (APTT)?

Answer 26

Activate factor XII

Question 27

What is thrombin's role in Hemostasis?

Answer 27

- Enhances the activity of Factors V and VIII - Induce platelet aggregation - Converts fibrinogen to fibrin

Question 28

What is the source of phospholipids for the intrinsic pathway?

Answer 28

Platelet factor 3

Question 29

What is the ISI an acronym for?

Answer 29

International sensitivity index

Question 30

What is the preferred test for monitoring LMWH therapy?

Answer 30

Anti-X a

Question 31

Patients with Protein S deficiency demonstrate what risk factor?

Answer 31

Increase risk for venous thromboembolic disease

Question 32

What causes a prolonged APTT to correct in a mixing study?

Answer 32

Factor XI deficiency

Question 33

What substances make up the PT reagent?

Answer 33

Thromboplastin and calcium chloride

Question 34

What is the best definition of Thrombophilia?

Answer 34

Tendency to thrombosis

Question 35

What is the function of von Willebrand factor?

Answer 35

Participates in platelet adhesion and transport of FVIII

Question 36

What is Anti-thrombin?

Answer 36

The most important coagulation inhibitor, inhibits thrombin formation.

Question 37

What increases Anti-thrombin activity?

Answer 37

Heparin sulfate (in vivo) or commercial heparin

Question 38

What would you give someone who overdosed on Heparin?

Answer 38

Protamine sulfate

Question 39

What can a deficiency in anti-thrombin lead to?

Answer 39

Can lead to severe, even fatal thrombotic events such as DIC, liver disease, nephrotic syndrome

Question 40

What is the Prothrombin Mutation Test?

Answer 40

Gene defect which results to increased amounts of Prothrombin and increased risk of thrombosis.

Question 41

What are lupus inhibitors/antibodies?

Answer 41

Anticoagulant, antibodies alter the phospholipid surface and are non-specific inhibitors.

Question 42

What are the important mechanisms of thrombosis in Lupus inhibitors?

Answer 42

- Inhibition of fibrinolytic system (factors XII and prekalikrein) - Inhibition of prostacyclin - Inhibition of protein C and S systems

Question 43

What is Heparin Co-Factor II?

Answer 43

An inhibitor inhibits thrombin more slowly than AT

Question 44

What is TFPI?

Answer 44

Tissue Factor Pathway Inhibitor binds and inactivates factors Xa and the tissue factor complex (TF:VIIa)

Question 45

What does Aspirin inhibit?

Answer 45

Inhibits platelet aggregation

Question 46

What does Heparin (unfractionated) inhibit?

Answer 46

Inhibits factors II, IX, X, XI, XII

Question 47

What is the therapeutic range for unfractionated Heparin?

Answer 47

0.2-0.4 units/mL

Question 48

How is the therapeutic range for Heparin determined?

Answer 48

By the Heparin response curve

Question 49

How is Low Molecular Weight Heparin produced?

Answer 49

From unfractionated heparin by depolymerization = reduced size.

Question 50

What is the function of Low Molecular weight heparin?

Answer 50

Causes a reduced activity to bind thrombin but increased ability to bind Xa

Question 51

What is LMWH effective in?

Answer 51

Deep Vein Thrombosis (DVT)

Question 52

What are the advantages of LMWH over standard heparin? (4)

Answer 52

1). Does not interact with platelets (less chance of bleeding) 2). No binding to plasma proteins, providing greater bioavailability and more predictable clearance from the circulation than standard heparin 3) Lower incidence of HIT 4) Lab monitoring is not necessary

Question 53

What is Warfarin (Coumadin)?

Answer 53

It is an oral anticoagulant

Question 54

What is the purpose of fibrinolysis?

Answer 54

To lyse unwanted clots and maintain hemostatic balance

Question 55

What is the purpose of a Tissue Plasminogen Activator?

Answer 55

It converts plasma plasminogen to activate Plasmin which breaks down fibrin

Question 56

What aids in the conversion of plasminogen to plasmin?

Answer 56

Factor XII, XIIa and Kalikirein

Question 57

What does Plasmin release when clots are dismissed?

Answer 57

D-Dimer

Question 58

What are the 3 pathways by which the fibrinolytic system is activated?

Answer 58

Extrinsic, Intrinsic and exogenous activation

Question 59

What is the primary source of extrinsic activation?

Answer 59

Comes from vascular endothelium

Question 60

What are the most commonly used exogenous activators? (3)

Answer 60

Urokinase, streptokinase and tissue plasminogen activator

Question 61

What is Urokinase responsible for?

Answer 61

Dissolves clots formed in the renal tubes of the kidney

Question 62

What is hemostatic balance?

Answer 62

A regulatory system of inhibitors exists to control both coagulation and fibrinolysis mechanisms.

Question 63

What is Alpha 2 Antiplasmin?

Answer 63

Principle inhibitor of fibrinolysis, 1:1 binding with plasmin, resulting in neutralization

Question 64

What is the function of the Thrombin-Activator Fibrinolysis Inhibitor (TAFI)?

Answer 64

Inhibits TPA and Urokinase

Question 65

What can a deficiency of TAFI lead to?

Answer 65

A hemorrhagic disorder

Question 66

What factors are in the contact group?

Answer 66

HMWK, Prekallikrein, XI and XII

Question 67

What factors are in the prothrombin group?

Answer 67

Factors II, VII, IX and X

Question 68

What factors are in the fibrinogen group?

Answer 68

Factors I, V, VIII and XIII

Question 69

What is secondary hemostasis?

Answer 69

Composed of the coagulation response (extrinsic and intrinsic pathways) to injury

Question 70

What is the purpose of the PT test in monitoring hemostasis?

Answer 70

- Detects factor deficiencies of the extrinsic pathway - Detects Vitamin K deficiency - Used to monitor therapeutic range for Coumadin therapy

Question 71

What is the advantage of using LMWH over UFH?

Answer 71

LMWH has less risk of heparin associated thrombocytopenia

Question 72

How would an APTT result be affected if the citrated plasma had platelets and was collected from a patient on unfractionated heparin?

Answer 72

Falsely decreased

Question 73

If the Prothrombin Time is prolonged and the Activated Partial Thromboplastin Time is normal, what is the likely cause of the abnormality?

Answer 73

Factor VII deficiency

Question 74

What factor deficiency might a patient have with a PT of 20.0s and an APTT of 35.0s?

Answer 74

VII

Question 75

Which of the following deficiencies can NOT be identified using the prothrombin time and the partial thromboplastin time?

Answer 75

Thrombocytopenia

Question 76

What will cause an acute hemorrhage in a patient?

Answer 76

Factor VIII deficiency

Question 77

What clinical conditions present with a low fibrinogen?

Answer 77

Liver disease, DIC, fibrinolysis (risk for bleeding)

Question 78

What causes a prolonged APTT and normal INR?

Answer 78

Factor VIII deficiency

Question 79

What disorder/condition would have a normal PT/INR result?

Answer 79

Factor IX deficiency

Question 80

What best describes a Clauss Fibrinogen?

Answer 80

Patient's results are read against a fibrinogen concentration reference curve

Question 81

What are the ingredients in APTT?

Answer 81

Silia ( activator), calcium (replaces calcium inactivated by anticoagulant)

Question 82

What does INR stand for?

Answer 82

International normalizing ratio

Question 83

Purpose of INR

Answer 83

Adjust for difference in thromboplastin sensitivity standardizing PT results worldwide

Question 84

What is the purpose of a mixing study?

Answer 84

Will correct within normal units for factor deficiency, will only show partial correction for lupus anticoagulant or factor inhibitors

Question 85

What clinical conditions present with a high fibrinogen?

Answer 85

Acute phase response, hyper coagulable state, dysfibrinogenemia (risk for thrombosis)

Question 86

What causes an elevated D-Dimer?

Answer 86

DVT, DIC,pregnancy, inflammation, trauma, post-OP

Question 87

State 2 different disease process/states that can cause elevated INR but normal APTT

Answer 87

- acquired Vitamin K deficiency (antibiotic Tx) -Vitamin K deficiency

Question 88

What does HIT cause?

Answer 88

Cause decreased platelet count and risk of thrombosis due to platelet activation

Question 89

What reagent is used for the Fibrinogen assay?

Answer 89

Thrombin

Question 90

How is DDIMER formed in a patient?

Answer 90

D-D fragment is composed of 2 D domains from separate fibrin molecules crosslinked by the action of Xllla. DDIMER is the specific product of digestion of crosslinked fibrin only

Question 91

What is the significance of a high DDIMER result?

Answer 91

Patient has a clot. Not specific as to what is causing the clot. A low DDIMER is sometimes of more value than a high DDIMER result. A low DDIMER rules out a clot

Question 92

The plasma of a patient with an APTT of 62.0s was mixed with 1:1 normal pooled plasma which resulted in an APTT of 58.0s. What does this suggest?

Answer 92

A lupus inhibitor

Question 93

A citrated blood sample with a hematocrit of 0.600 L/L or more is run for coagulation studies. If the APTT results are 65.0s should the volume of the anticoagulant used:

Answer 93

Reduced in volume

Question 94

If the Prothrombin Time is prolonged and the Activated Partial Thromboplastin Time is normal, what is the likely cause of the abnormality?

Answer 94

Factor VII deficiency

Question 95

A prolonged plasma thrombin time indicates a deficiency in:

Answer 95

Fibrinogen

Question 96

Hemophilia A and B may be suspected in patients with a:

Answer 96

Prolonged APTT, normal INR

Question 97

What best describes a Clauss Fibrinogen?

Answer 97

Patient's results are read against a fibrinogen concentration reference curve