Abstract: The invention relates to a method for distinguishing between different states or forms of diseases and disorders characterized by thrombocytopenia and/or by spontaneous interaction between Von Willebrand Factor (vWF) and platelets, and/or to predict the progression of such a disease or disorder, said method comprising the steps of providing at least one biological sample obtained from a patient suffering from, or suspected to suffer from, at least one disease or disorder characterized by thrombocytopenia and/or by spontaneous interaction between Von Willebrand Factor (vWF) and platelets and of determining the amount of activated vWF in said biological sample, in which the amount of activated vWF in the sample is representative for the different states or forms of the disease or disorder.