Temporal Aspects of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia is a syndrome of antibody-mediated thrombocytopenia that paradoxically is often associated with thrombosis. 1 – 5 Most patients with this disorder produce IgG antibodies 6 , 7 against complexes of platelet factor 4 and heparin. 8 – 11 Platelet factor 4, a small peptide stored within the alpha granules of platelets, binds to heparin and is released into the blood during treatment with heparin. 12 In vitro, IgG–platelet factor 4–heparin complexes can activate platelets, 13 , 14 a finding that raises the possibility that platelet activation in vivo contributes to the thrombotic complications of heparin-induced thrombocytopenia. 15 , 16 Typically, heparin-induced thrombocytopenia begins with the appearance of thrombocytopenia about . . .