VWF Activity Clotting Test - Von Willebrand Factor (VWF) Activity Test

This test measures the biological function (activity) of von Willebrand factor (VWF) in plasma, usually using an assay based on VWF's ability to bind to platelets (such as the Ristocetin Cofactor Activity Assay, VWF:RCo). This test indirectly measures VWF's ability to mediate platelet adhesion to the damaged blood vessel wall, the essential first step in platelet plug formation. It is a crucial component of the accurate diagnosis of von Willebrand disease.