Term
| A previously healthy 26-year-old man presents with a DVT and PE. He has not been immobilized recently, and he has no history of prior thrombosis. He reports that his grandmother and an uncle both had a history of “blood clots”. The next morning on rounds, your attending suggests that you work him up for a hypercoagulable state. What tests should you order? |
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Definition
- Factor V Leiden
- Prothrombin G20210A mutation
- Antithrombin level
- Protein C and S level
- Homocysteine level
- Antiphospholipid antibodies
- Lupus anticoagulant
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Term
Which coagulation factors are inhibited by warfarin? |
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Definition
2, 7, 9, 10, Protein S and C |
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Term
| What is the treatment for an overdose of warfarin? Of heparin? |
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Definition
a. Vitamin K, fresh frozen plasma (with all coagulation factors)
b. IV protamine sulfate |
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Term
What are the actions of thrombin? |
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Definition
Converts fibrinogen to fibrin, activates Protein C, activates factor V and factor VIII |
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Term
What are the actions of antithrombin? |
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Definition
Inactivates Thrombin and Factors VIIa, IXa, Xa, XIa, XIIa |
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Term
| What are the actions of protein C? |
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Definition
Inactivates Factors Va and VIIIa
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Term
What are the actions of fibrin? |
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Definition
| Basic building block of a stable blood clot |
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Term
What are the actions of plasmin? |
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Definition
| Breaks down the crosslinked Fibrin Mesh of a blood clot |
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Term
| What is the most common inherited hypercoagulable disorder? |
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Definition
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Term
| Because of the increased risk of thrombosis, in whom are oral contraceptives absolutely contraindicated? |
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Definition
- Women >35 who smoke heavily (more than 15 cigs daily)
- Women w/ history of thromboembolic event or stroke
- History of thrombophlebitis or hypercoagulable state are relative contraindications |
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Term
| What are the four basic stages of hemostasis? |
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Definition
- Platelet plug
- Coagulation cascade
- Termination of clotting
- Fibrinolysis and clot removal |
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Term
| What is tissue factor, and where is it found? |
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Definition
- Cofactor for activation of Factor VII
- Extrinsic pathway, VII to VIIa to Factor X |
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Term
| What is the name of primary pathway for initiating coagulation (formerly known as the ‘extrinsic pathway’)? |
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Definition
|
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Term
| What is the name of the secondary pathway for initiating coagulation (formerly known as the ‘intrinsic pathway’)? |
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Definition
| Contact Factor pathway, involves Factor XII, XI, IX, VIII, joins common pathway at Factor X |
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Term
| What are the two main enzymes in the antithrombotic pathway, which inactivate the coagulation cascade? |
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Definition
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Term
| How does the anticoagulant heparin work? |
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Definition
| Binds to antithrombin, makes 1000x more active |
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Term
| What does bleeding time measure? |
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Definition
- Cut patient’s arm, blot blood, about 2-9 min to stop, measures platelet function
- Disorders of coagulation cascade will not affect |
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Term
| What does the prothrombin time (PT) measure? |
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Definition
- Take plasma, add tissue factor
- Tests tissue factor pathway and final common pathway
- Factors VII, X, V, prothrombin |
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Term
| What does the partial thromboplastin time (PTT) measure? |
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Definition
- Add phospholipids, and silica or something to activate contact activation pathway
- Test Contact activation pathway and final common pathway
- Tests Factors XII, XI, IX, VIII
- Tests Factors X, V, prothrombin |
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Term
| What lab test is used to monitor anticoagulation with heparin? |
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Definition
| PTT, keep at about 2x normal level (because heparin affects contact activation pathway via antithrombin |
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Term
| What lab test is used to monitor anticoagulation with warfarin? |
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Definition
| PT (because warfarin affects tissue factor pathway via tissue factor |
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Term
| What lab test is used to monitor anticoagulation with enoxaparin? |
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Definition
- Don’t monitor, just dose patient based on weight
- But, can measure Anti-factor Xa activity |
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Term
|
Definition
- Stasis of blood
- Endothelial injury
- Hypercoagulable state |
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Term
| How does the Factor V Leiden cause a hypercoagulable state? |
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Definition
| Makes Factor Va resistant to inactivation by protein C |
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Term
| In what ethnic groups are Factor V Leiden and the Prothrombin G20210A mutation more commonly found? |
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Definition
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Term
| What is the treatment for patients with a history of thrombosis and an inherited hypercoagulable disorder? |
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Definition
| Life-long anticoagulation, usually warfarin |
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Term
| What acquired conditions predispose to thrombosis? |
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Definition
- Pregnancy, post-partum period
- Oral contraceptives
- Estrogen replacement therapy
- Malignancy
- Myeloproliferative diseases (chronic myeloid leukemia, polycythemia vera)
- Hyperhomocysteinemia
- Smoking |
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Term
| What vitamin deficiencies cause hyperhomocysteinemia? |
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Definition
| pyridoxine (B6), folic acid (B9), B12 |
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Term
| What lab and clinical findings are caused by lupus anticoagulants? |
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Definition
- Prolonged PTT
- Clinical: pro-thrombotic, hypercoagulable state |
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