Thrombotic event is seen in all of following except

ITP Idiopathic thrombocytopenic purpura is not associated with thromboss. Its main clinical manifestation is bleeding which occurs due to thrombocytopenia. Heparin induced thrombocytopenia (HIT) is the most impoant and most frequent drug induced immune mediated type of thrombo- cytopenia. - It is seen in about 1-5% of patients on heparin. - In patients receiving heparin for the first time, the onset of thrombocytopenia usually occurs 5-10 days after the administration of heparin. - The thrombocytopenia in HIT is usually moderate in severity with a median platelet count being between 50 and 80 x 109/L. "Despite thrombocytopenia bleeding is rare. On the other hand heparin induced thrombocytopenia is strongly associated with thrombosis which frequently leads to diagnosis of heparin induced thrombocytopenia". -Thrombosis in heparin induced thrombocytopenia is associated with a moality of approximately 20-30% with an equal percentage of patients becoming permanently disabled by amputation, stroke or other causes. - Thromboembolic complications can be venous, aerial both and include deep venous thrombosis, pulmonary embolism myocardial infarction, thrombotic stroke and occlusion of limb aeries. The mechanism underlying heparin induced thrombocytopenia is an immune response. The principal antigen is a complex of heparin and platelet factor 4 (PF4). Patients who develop HIT produce antibodies against Heparin platelet F4 complex. Thrombocytopenia in HIT is largely due to the clearance of activated platelets and antibody coated platelets by the reticuloendothelial system.