Coagulation Cascade

Question 1

PT

Answer 1

tests function of 1, 2, 5, 7, 10 (extrinsic pathway), warfarin works on PT

Question 2

PTT

Answer 2

tests function of all factors except 7 and 13 (intrinsic) –> heparin

Question 3

What is antithrombin?

Answer 3

1. Inhibits thrombin and factors 7a, 9a, 10a, 11a, and 12a

2. Activated by heparin

Question 4

Discuss the mech of heparin

Answer 4

1. Cofactor for the activation of antithrombin
2. Decrease thrombin
3. Decrease Xa
4. Short half-life
5. Affects PTT

Question 5

What are the clinical use of heparin?

Answer 5

Immediate anticoagulation for pulmonary embolism, stroke, acute coronary syndrome, MI, DVT

Question 6

Can heparin be used during pregnancy?

Answer 6

yes (does not cross placenta)

Question 7

What is the characteristics of low-molecular-weight heparins (enoxaparin)?

Answer 7

1. Acts more on Xa
2. Have better bioavailability and 2-4 times longer half-life
3. Can be administered subcutaneously and w/o lab monitoring

Question 8

What is the toxicity of heparin?

Answer 8

1. Bleeding

2. Thrombocytopenia (HIT)

Question 9

What is the antidote for heparin?

Answer 9

protamine sulfate

Question 10

Discuss about heparin-induced thrombocytopenia (HIT)

Answer 10

Heparin binds to platelet factor IV, causing antibody production that binds to and activates leading to their clearance and resulting in a thrombocytopenic, hypercoagulable state.

Question 11

What is a Trousseau’s sign?

Answer 11

when carpal spasms develop if a blood pressure cuff is inflated above systolic pressure over the