We propose two mechanisms for thrombin activation: firstly, thrombin is activated when platelets are “consumed” during hemostasis, and thrombin cleaved IL-1α from the platelet surface; secondly, thrombocytopenia causes microvessel leakage (purpura, petechiae) where prothrombin is exposed to and activated by tissue factor. This evidence concerns the gene IL1A and Thrombocytopenia.