Laboratory Evaluation of Heparin‐Induced Thrombocytopenia

Heparin‐induced thrombocytopenia (HIT) is a prothrombotic disorder caused by platelet‐activating IgG antibodies that recognize platelet factor 4 (PF4) heparin complexes. Laboratory detection of such “HIT antibodies” is required for definitive diagnosis. Laboratory tests for HIT can be broadly classified into: (a) platelet activation (or functional) assays; and (b) PF4‐dependent antigen assays (immunoassays). An important diagnostic problem is …