Analysis of von Willebrand factor in platelets of patients with various forms of von Willebrand disease: Is there a clinical relevance?

Besides the investigation of coagulation factor VIII:c and von Willebrand f actor in plasma, VWF antigen and VWF collagen-binding activity in platelets of 24 patients with various forms of von Willebrand disease were analysed. No platelet vWF:Ag or vWF:CBA was detectable in type 3 patients (n = 4). I n contrast 6 out of 7 patients with type 2 vWD had normal or increased vWF levels. TWO type 1 patients (out of n = 13) with low von Willebrand factor in platelets had no increased bleeding tendency. In two other individuals w ith normal amounts of von Willebrand factor in platelets and low plasmatic VWF and factor VIII:c, more frequent bleeding episodes reflecting the low p lasmatic levels were observed in a long-term follow-up. Conclusion In our patients, bleeding history corresponded to plasmatic leve ls of FVIII:c and vWF.