title: Delayed-onset heparin-induced thrombocytopenia.
abstract: Delayed-onset heparin-induced thrombocytopenia is a syndrome in which thrombocytopenia and thrombosis begin several days after heparin discontinuation. Delayed-onset heparin-induced thrombocytopenia is caused by immunoglobulin G antibodies that are reactive against the heparin-platelet factor 4 complex in the absence of circulating heparin. We describe 2 patients with delayed-onset heparin-induced thrombocytopenia who presented to the emergency department. An 88-year-old man and a 62-year-old man experienced thrombocytopenia and thrombosis 9 or more days after heparin cessation and demonstrated a further decrease in platelet count on reexposure to heparin. Delayed-onset heparin-induced thrombocytopenia should be included in the differential diagnosis of a patient with recent heparin exposure who presents with thrombosis or thrombocytopenia.
authors.affiliation: Department of Pharmacy Practice, Wayne State University, William Beaumont Hospital, Royal Oak, MI 48201, USA. msmythe@beaumont.edu
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Smythe
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Stephens
authors.forename: Joan C
authors.initials: JC
authors.lastname: Mattson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D004636:Emergency Service, Hospital; D006493:Heparin / Q000009:adverse effects* / Q000276:immunology; D006629:Hirudins / Q000031:analogs & derivatives*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010978:Platelet Factor 4 / Q000276:immunology; D011994:Recombinant Proteins / Q000627:therapeutic use; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000276:immunology; D013997:Time Factors; D020246:Venous Thrombosis / Q000139:chemically induced / Q000188:drug therapy
chemical_list: D000925:Anticoagulants; D006629:Hirudins; D011994:Recombinant Proteins; D010978:Platelet Factor 4; D006493:Heparin; C083544:lepirudin