VON WILLEBRAND DISEASE
The most common bleeding disorder is von Willebrand disease (VWD). It is congenital and caused by deficiency or abnormality in a plasma protein central to blood clotting known as the von Willebrand Factor (named after the Finnish physician who first identified the disorder).
Von Willebrand Factor (VWF) is the “glue” that helps platelets in the blood stick together to form a clot where a blood vessel has been ruptured. It also binds and stabilizes the clotting factor Factor VIII, so in patients with VWD, the lack of VWF activity results in premature elimination of Factor VIII in the circulation, thereby resulting in a dual defect in the body’s ability to stop bleeding. People with VWD produce normal amounts of Factor VIII, but with deficient VWF the clotting factor does not stay in the system long enough to adequately carry out its function.
There are three generally recognized forms of the disease:
Type I: The most common and mildest form of von Willebrand disease. Levels of von Willebrand Factor are lower than normal, and levels of Factor VIII may also be reduced.
Type II: In this form of von Willebrand disease, there is normal and sufficient von Willebrand Factor but it is deficient and does not work properly. The abnormality in the factor can vary and accordingly there are several subtypes of Type II von Willebrand disease – important to determine because treatment for each is specific.
Type III: The most severe form of von Willebrand disease in which VWF is nearly or completely absent along with very low levels of Factor VIII.
People with von Willebrand disease can bruise easily; suffer frequent nosebleeds that can be difficult to stop; have heavy menstrual bleeding; and experience heavier and longer than normal bleeding after injury, surgery, childbirth, or dental work. In its most severe form, it can lead to spontaneous joint and organ bleeding and can be life-threatening.
Some patients respond favorably to injection of desmopressin acetate (DDAVP) but the most effective treatment and prophylaxis for VWD – especially in its more severe forms - is therapy with plasma-derived von Willebrand Factor products.
1. Federici AB. Classification and clinical aspects of von Willebrand disease. In: Textbook of Haemophilia 2nd Edition, Lee CA, Berntorp E, Hoots K (eds). Oxford: Wiley-Blackwell 2010. 302–308.