Heparin‐Induced Thrombocytopenia

Heparin‐induced thrombocytopenia (HIT) is a relatively common prothrombotic adverse effect of heparin both unfractionated and (less often) low‐molecular‐weight heparin caused by antibodies that recognize multimolecular complexes of (positively charged) platelet factor 4 (PF4) bound to (negatively charged) heparin. The antibodies strongly activate platelets through their Fc?RIIa receptors, producing a procoagulant platelet response that results …