Clotting Disorders and Hypercoagulable

Question 1

Prothrombin Time and INR

Answer 1

time in seconds it takes the plasma to clot after adding calcium and thromboplastin

• Extrinsic pathway
• Monitoring warfarin

Question 2

Partial Thromboplastin Time (PTT)

Answer 2

time in seconds for plasma to clot after adding phospholipid and calcium

-Intrinsic pathway

Question 3

What if PT and PTT are decreased?

Answer 3

ignore, not clinically relevant

Question 4

IF you do a mixing study and adding normal blood doesn’t change the fact that clotting time is prolonged (PTT), what’s the issue?

Answer 4

inhibitor

Ex. heparin, Lupus anticoagulant

Question 5

IF you are doing mixing studies and adding normal blood normalizes the clotting time (PTT), what’s the issue?

Answer 5

factor deficiency of the intrinsic pathway

Ex. VIII, IX, XI, XII

next step–> get clotting factor assays to determine which is missing

Question 6

What should you suspect if patient is a young female, no history of bleeding, clot with baseline prolonged PTT and not on anticoagulation?

Answer 6

Lupus anticoagulant

Question 7

Mixing Study: PT

Answer 7

If it corrects–> deficiency of factors II, VII, X, or fibrinogen

If it doesn’t correct–> inhibitors (ex. warfarin)

Question 8

Warfarin

Answer 8

• interferes with “1972”
• Pregnancy category X

Most common indications:

1. Afib
2. VTE
3. Mechanical valve (INR 2.5-3.5)*

Question 9

Unfractionated Heparin (UFH)

Answer 9

• inhibits IIa (thrombin) and Xa

- Not absorbed subcutaneously

Question 10

Low Molecular Weight Heparin (LMWH)

Answer 10

• inhibit Xa and some IIa
• Lovenox is safe in pregnancy
• Well absorbed subcutaneously
• Doesn’t need to be monitored (unless pt. is very thin or obese)

contraindications: ESRD

Question 11

Fondaparinux

Answer 11

• inhibits Xa
• binds to antithrombin III
• Use this is pt has pork allergy***

Question 12

Rivaroxaban (Xeralto), Apixaban (Eliquis)

Answer 12

direct Xa inhibitors

Question 13

Dabigatran (Pradaxa)

Answer 13

direct thrombin inhibitor

Question 14

Reversals?

Answer 14

Warfarin–>vitamin K

Heparin, Lovenox–> Protamine

Question 15

Virchow’s Triad

Answer 15

1. Venous stasis
2. Venous trauma
3. Hypercoagulable state

Question 16

Deficiency in what molecules causes hypercoagulable state?

Answer 16

1. Protein C
2. Protein S
   - both of these will give 10x more likelihood to form clot
3. Antithrombin III
   - 20x more likelihood to form clot

-usually these help prevent clots, but if they are deficient you will clot more

Question 17

What are Protein C and S dependent on?

Answer 17

Both are vitamin K dependent

Question 18

Factor V Leiden Mutation

Answer 18

-mutation with single substitution makes this resistant to inactivation by Protein C so continues to clot

• MC in whites
• Heterozygous 5x risk
• Homozygous 80x risk

Question 19

Prothrombin Gene G20210A mutation

Answer 19

Causes greater function of prothrombin factor II

Question 20

Hyperhomocysteinemia

Answer 20

• Increased risk of VTE in arteries
• Deficiency of Vitamin B6, B12, and folic acid

Tx: Vitamin B12 and folate

Question 21

Antiphospholipid Ab Syndrome

Answer 21

• Recurrent arterial or venous thrombosis
• Loss of fetus
• (+) antiphospholipid antibodies (ex. anticardiolipin antibody)

Question 22

LAC and Anticardiolipin A

Answer 22

• antibodies (IgG, or IgM) against phospholipids
• More arterial clotting
• Sneddon Syndrome [livedo reticularis + neurologic abnormalities]

Question 23

Best test for suspected VTE?

Answer 23

Doppler ultrasound**

-more accurate above the knee

Question 24

Best test for PE?

Answer 24

CT angio

Question 25

What if you suspect PE but the patient has renal insufficiency, pregnant, or can’t do iodine?

Answer 25

VQ

Question 26

Why does Warfarin initially increase the likelihood of clot?

Answer 26

initially drops Protein C and S (which prevent clotting normally)

Question 27

If a patient has had their first VTE how long should you put them on anticoagulation?

Answer 27

3-6 months

Question 28

First VTE and hypercoagulable state do they need lifelong AC?

Answer 28

No

Question 29

IF patient has recurrent VTE and is hypercoagulable do you do lifelong AC?

Answer 29

Yes

Question 30

When should you give Tissue plasminogen activator (tPA) to a PE patient?

Answer 30

significant hemodynamic instability and RV strain

Question 31

Patient has a superficial clot. What’s the tx?

Answer 31

NSAIDs/ASA + warm compress

Question 32

When should you consider anti-coagulation in superficial throbophlebitis?

Answer 32

• > 5cm
• Very symptomatic
• If occured while on ASA