Von willebrand factor

von Willebrand factor (VWF)is a blood glycoprotein involved in hemostasis, specifically, platelet adhesion. It is deficient and/or defective in von Willebrand disease and is involved in many other diseases, including thrombotic thrombocytopenic purpura.

1. VON WILLEBRAND FACTOR SURAMYA BABU

2. VON WILLIBRAND FACTOR (VWF) is a blood glycoprotein involved in hemostasis Synthesis in endothelium and megakaryocytes Forms large multimer Anchors platelet to sub-endothelium

3. Reference range VWF Ag: 61.3-158 % VWF activity: 49-170 %

4. Relationship between blood group and VWF level Blood groups VWF LEVEL % O 74.8 A 105.9 B 116.9 AB 123.9

5. VWF DECREASED CONDITION VWF INCREASED CONDITION Von Willibrand disease Cardiovascular disease Thrombotic thrombocytopenic purpura Neoplastic disease Heydes syndrome Connective tissue disease Hemolytic uremic syndrome

6. Von willibrand disease Most common inherited( autosomal dominant) bleeding disorder Incidence: 1:100 – 1: 1000 Presents most commonly as platelet –type bleed Spontaneous bleeding, mucocutaneous bleed Prolonged bleeding time , normal platelet count

7. Classification of VWD TYPE 1 VWD TYPE 2 VWD TYPE 3 VWD Most common 75-80 % Less common 15-20 % Rare (1;500,000) Autosomal dominant Autosomal dominant Autosomal recessive Quantitative deficiency (reduced VWF) Qualitative deficient (dysfunctional VWF) Absent VWF Mild Mild to moderate Severe, present in early childhood

8. Lab evaluation of VWD ASSAY TYPE 1 VWD TYPE 2 VWD TYPE 3 VWD VWF antigen normal VWF activity Multimer analysis Normal Normal Absent

9. Treatment of VWD CRYOPRECIPITATE Source of fibrinogen , factor VIII AND VWF Only plasma fraction that consistently contains VWF multimers DDAVP (DEAMINO -8 – ARGININE VASOPRESSIN) It increase plasma VWF levels by stimulating secretion from endothelium Not generally used in type 2 disease Dosage 0.3 ug/kg q 12 hour intravenously Factor VIII concentrate virally inactivate product