Von Willebrand disease is defined as impaired Von Willebrand Factor (VWF) function resulting in impaired haemostasis.
It is the commonest of the inherited bleeding disorders.
Von Willebrand’s factor is a glycoprotein made in epithelial cells and megakaryocytes which:
- Acts as a bridging molecule between platelets and the sub-endothelium
- Helps platelets bind to each other
- Is a carrier of factor VIII, helping to prevent its breakdown in the circulation
Types of Von Willebrand’s disease:
- Type 1
- Decreased quantity of VWF
- Mild to moderate bleeding
- Type 2 (several subtypes exist)
- Qualitative defect - abnormal types of VWF
- Type 3
- Trace of VWF
- Autosomal recessive
- Severe bleeding disorder
Presentation includes
- Prolonged bleeding after injury
- Easy bruising
- Prolonged epistaxis
- Menorrhagia
- Oral bleeding (eg after tooth extraction)
Investigation
- VWF antigen level
- At least 2 occasions
- Will be low or normal in Von Willebrand’s disease
- Note it is elevated by exercise and hyperthyroidism
- It is decreased by hypothyroidism
- Von Willebrand factor ristocetin cofactor activity
- PT, platelet count and fibrinogen levels are usually normal
- aPPT usually prolonged
Treatment
- Desmopressin (DDAVP)
- Increases factor VIII and VWF
- Useful in type 1, variably useful in type 2, not useful in type 3
- Tranexamic acid
- An antifibrinolytic agent
- Useful in management of epistaxis and menorrhagia
- Avoid in patients with history of thromboembolic disease or current upper urinary tract bleeding
- VWF/factor VIII concentrate
Acquired von Willebrand syndrome is associated with
- Myeloproliferative disorders
- Autoimmune diseases
- Neoplasia
- Lymphoproliferative disorders
- Structural cardiac defects
Small print gem: VWF is an acute phase protein and so may be raised in infection, malignancy and inflammatory conditions.
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