VWD

Question 1

What is VWD?

Answer 1

Most common inherited bleeding disorder characterised by low levels or reduced activity of VWF

Question 2

Inheritance of VWD

Answer 2

autosomal dominant
May also be acquired, less common

Question 3

Types of VWD

Answer 3

type 1 (75%, least severe bleeding, oromucosal, mennorhagia, asx) - reduced factor level
Type 2 (more severe bleeding) - dysfunctional VWF
Type 3 - severely reduced or absent factor, most severe bleeding (can be MSK)

Question 4

Subtypes of VWD TYPE 2

Answer 4

Type 2a: loss of platelet binding (VWF can’t bind to GPIb receptor on plt) + loss of HMW multimers

Type 2b: gain of function mutation, VWF binds platelets too easily, clearing plt and VWF from circulation

Type 2m: low platelet binding (same as type 2a) but no loss of HMW multimers

Type 2N: VWF can’t find factor VIII

Question 5

Labs for VWD

Answer 5

VWF antigen (levels <30% aka <30IU/L diagnostic, <50% with bleeding history diagnostic. >50% normal)

Platelet dependent VWF activity

Factor VIII activity - low in type 2 (bc dysfunctional VWF can’t bind and protect factor VIII) and type 3

Ratio of VWF antigen:activity is normal in type 1 (low factor, low activity) and disproportionately high in type 2 (normal factor, low activity)

Question 6

Treatment of bleeding in VWD

Answer 6

Severe bleeding - give daily VWF concentrate (ie biostate with factor III/VWF) + TXA.
Can also use desmopressin (increases tissue synthesis of VWF)