Global Hemostatic Methods in Hemophilia and Von Willebrand's Disease

Patients with hemophilia who have the same level of deficient factor(s) may express different severity of clinical presentation and bleeding tendency. Therefore a test which could determine overall hemostasis rather than simple concentration of a single deficient factor may correlate better with clinical phenotype in these patients.

The investigators will therefore study the usefulness of global hemostatic methods (endogenous thrombin potential (ETP), overall hemostatic potential (OHP), fibrin clot structure) and microparticles in the prediction of severity of bleeding and estimation of response to the treatment in patients with hemophilia.

Since hemophilia patients on prophylactic treatment virtually do not bleed, additional patients who are treated on demand only will be included enabling to study possible modulatory effects of different hemostatic factors (particularly prothrombotic and thrombin activatable fibrinolysis inhibitor (TAFI)) on clinical presentation. The investigators will correlate both those factors and clinical severity with global hemostatic methods.

The investigators expect to prove that individual tailoring of the treatment, which may enable lowering the prophylactic dose of factor concentrate without increasing the risk of bleeding, is justified in some hemophilia patients. This approach would reduce the amount of necessary factor concentrate in certain patients and decrease the cost (which represents extensive burden for health care systems) of treatment without potential risk for the patients.