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Von Willebrand disease

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.


References
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