Delayed-Onset Heparin-Induced Thrombocytopenia and Cerebral Thrombosis after a Single Administration of Unfractionated Heparin

Abstract

Delayed-onset heparin-induced thrombocytopenia, a newly described syndrome of immune-mediated thrombocytopenia that begins several days after heparin therapy has been discontinued,^1,2 is caused by IgG antibodies that are reactive against platelet factor 4–heparin complexes that activate platelets even in the absence of pharmacologic heparin.¹ The minimal amount of heparin required to initiate this syndrome is unknown.