How are the platelet disorders of von Willebrand disease (vWD) characterized?

Updated: Aug 05, 2017
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Answer

Bleeding time is prolonged in persons with von Willebrand disease. Because the von Willebrand protein is phase-reactant (ie, increased synthesis in the presence of inflammation, infection, tissue injury, and pregnancy), a mild prolonged bleeding time may be normalized, resulting in difficulty in diagnosis.

In addition to the prolonged bleeding time, characteristic abnormalities in platelet aggregation tests occur. In patients with von Willebrand disease, platelets aggregate normally to all agonists except the antibiotic ristocetin, which induces binding of the von Willebrand protein to platelets, similar to what happens with platelets following vessel wall injury in vivo. Ristocetin-induced platelet aggregation correlates with the platelet-aggregating activity of the von Willebrand protein. The levels of coagulation factor VIII are also low, due to the decrease in vWf, the carrier of factor VIII in plasma.


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