VON WILLEBRAND DISEASE: DIAGNOSIS AND TREATMENT

Abstract

Background. Von Willebrand disease (VWD) is a most frequently inborn bleeding disorder caused by quantitative or qualitative defects of von Willebrand factor (VWF). VWF promotes platelet-vessel wall (adhesion) and plateletplatelet interaction (aggregation). It is also the carrier for factor VIII (F VIII) in plasma. A deficiency of VWF may results in impairment of both, primary and secondary haemostasis. Therefore, patients with VWD can have bleeding symptoms typical fot the defect in primary haemostasis (mucocutaneous haemorrhages). In severe deficiency of VWF there are also haemarthroses and haematomas typical for patients with coagulation defects. Several types and subtypes of VWD have been described. The diagnosis is based on measurements of VWF concentration and activity and F VIII activity in plasma. The tests identifying VWD subtypes are ristocetin induced platelet agglutination (RIPA), multimeric analysis of VWF and measurement of the binding of VWF to F VIII. Conclusions. Due to heterogeneity of VWF defects, the correct diagnosis of types and subtypes is sometimes difficult but is important for appropriate treatment. There are two main therapeutic options for patients with VWD: desmopressin and blood derived concentrates of F VIII/VWF. In certain cases antifibrinolytics and hormones can be suitable treatment. Desmopressin is the treatment of choice in patients with type 1 VWD. It raises endogenous F VIII and VWF and thereby corrects the intrinsic coagulation defect as well as the prolonged bleeding time (BT) or closure time (CT-PFA100) in most type 1 VWD patients. In type 3 and in the majority of type 2 patients desmopressin is not effective and it is necessary to use concentrates containing F VIII and VWF. These are always effective in raising of F VIII activity, whereas the BT/CT may not be completely corrected, but the normalisation of the BT/CT is not always necessary.