Hematology #4 (VWD, Factor V, C/S, Antithrombin III, HIT)

Question 1

What is Von Willebrand Disease?

Answer 1

Autosomal dominant disorder with ineffective platelet adhesion due to deficient or defective vwF

Question 2

True or False: VWD is the most common hereditary bleeding disorder

Answer 2

True

Question 3

What are the two functions of Von Willebrand Factor?

Answer 3

-Promotes platelet adhesion
-Prevents Factor 8 Degradation

Question 4

Symptoms of Von Willebrand Disease

Answer 4

-Mucocutaneous bleeding (epistaxis, bleeding gums, petechiae, purpura, bruising, menorrhagia)

Question 5

What are the initial labs that are drawn for VWD and what do they show?

Answer 5

Prolonged PTT (corrects with mixing studies)
PTT and bleeding time worse with Aspirin
Platelet count normal

Question 6

What other screening tests can be done for VWD?

Answer 6

-Plasma VWF antigen: decreased antigen or activity (30 IU or less)
-Plasma VWF activity: Ristocetin cofactor activity
-Factor VIII activity decreased

Question 7

There are three types of VWD…explain them.

Answer 7

-Quantitative deficiency (MC type)
-Qualitative deficiency (non-functional VWF)
-Absent VWF (Complete lack of VWF)

Question 8

Treatment for VWF
-Mild to Moderate Bleeding
-Severe
-Minor Procedures
-Major Procedures

Answer 8

-Mild to Moderate: DDAVP
-Severe: VWF-containing product (Factor VIII concentrates)
-Minor Procedures: Desmopressin
-Major Procedures: VWF containing products

Question 9

MC type of inherited cause of hyper coagulability (thrombophilia)

Answer 9

Factor V Leiden Mutation

Question 10

Explain the pathophysiology of Factor V Leiden Mutation

Answer 10

Mutated Factor V is resistant to breakdown by activated protein C, leading to increased hypercoagulability

Question 11

Symptoms of Factor V Leiden Mutation

Answer 11

-Increased incidence of DVT, PE, hepatic vein, or cerebral vein thrombosis
-Increased miscarriages during pregnancy

Question 12

Treatment for Factor V Leiden Mutation

Answer 12

-Indefinite anticoagulation

Question 13

In a patient with Factor V Leiden Mutation, what should you give during pregnancy to prevent miscarriages?

Answer 13

LMWH

Question 14

What are Proteins C and S?

Answer 14

Vitamin K-dependent anticoagulant proteins produced by the liver that stimulate fibrinolysis and inactivate Factors V and VIII

Question 15

Therefore, decreased levels of Protein C and Protein S lead to ________

Answer 15

hypercoagulability

Question 16

Symptoms of Protein C and Protein S deficiency

Answer 16

Increased incidence of DVT and PE
Warfarin induced skin necrosis

Question 17

What does antithrombin III normally do?

Answer 17

Inhibits coagulation by neutralizing activity of thrombin (factors IIa, IXa, and Xa)

So, decreased levels lead to clotting

Question 18

Treatment for antithrombin III deficiency if..

-Asymptomatic
-Thrombosis

Answer 18

-Asymptomatic: anticoagulation before surgery

-Thrombosis: high dose IV heparin followed by oral anticoagulation therapy indefinitely

Question 19

Heparin Induced Thrombocytopenia (HIT) is thrombocytopenia within the first ______ days of initiation of Heparin

Answer 19

-5-10 days

Question 20

Treatment for HIT

Answer 20

-Immediate discontinuation of all Heparin + initiation of direct thrombin inhibitors (Argatroban, Lepirudin)

Question 21

Heparin works on what two steps in the coagulation cascade?

Lovenox (LMWH) only works on which step?

Answer 21

Heparin: works on X–>Xa and prothrombin –> thrombin

Lovenox: only works on X–> Xa