Abstract
For patients with high platelet counts an inverse relationship has been established
between platelet counts and large vWf multimers in plasma. Platelets are currently
thought to be primarily involved in the pathogenesis of this decrease in plasma large
vWf multimers, presumably by binding large vWf multimers, resulting in their effective
removal from the circulation and/or by degrading (plateletbound) vWf. In patients
with myeloproliferative disorders associated with high platelet counts, a decrease
in large vWf multimers in plasma may potentially compromise primary hemostasis. Patients
with reactive thrombocytosis exhibit a similar reduction in large vWf multimers in
plasma, but their clinical course is usually not complicated by bleeding, probably
as a consequence of increased circulating vWf levels due to the behavior of vWf as
a reactive protein, which compensates for the relatively decreased levels of large
vWf multimers in plasma.
Keywords:
von Willebrand factor - platelets - thrombocytosis - thrombocythemia - myeloproliferative
disorders - von Willebrand disease
