Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an adverse prothrombotic disorder caused by an immune response to complexes of platelet factor 4 and polyanions. The clinical relevance of HIT results from the wide use of heparin, which is the reason that the absolute number of patients affected by HIT is high. HIT is currently the most frequent immune-mediated adverse drug reaction affecting blood cells.This chapter will address the clinical presentation of HIT and summarize recent findings on its pathogenesis including the concept that HIT is likely a misdirected bacterial host-defense mechanism. Description of laboratory tests for HIT and an outline on current recommendations for management of affected patients provide information relevant for daily clinical practice.