title: Heparin-induced thrombocytopenia.
abstract: Thrombocytopenia is a frequent and sometimes insidious complication of anticoagulant therapy with heparin. Two types of heparin-induced thrombocytopenia with a distinct aetiology have been recognized. Type I is characterized by a mild thrombocytopenia of early onset which requires careful monitoring but usually not the cessation of heparin therapy. The mild thrombocytopenia is probably due to the mild pro-aggregatory properties of heparin and can be more severe in the presence of other predisposing factors, e.g. sepsis. Type II heparin-induced thrombocytopenia is more severe and usually occurs after a period of 7-10 days. Heparin therapy should be ceased immediately and other anticoagulant therapy initiated. The thrombocytopenia is believed to be due to the development of a heparin-dependent antibody that causes platelet aggregation and release. The precise mechanism of heparin-dependent antibody-platelet interaction is still not entirely clear but probably involves the binding of an antibody-heparin immune complex to the platelet Fc receptor.
authors.affiliation: Haematology Department, St. George Hospital, Kogarah, New South Wales, Australia.
authors.forename: B H
authors.initials: BH
authors.lastname: Chong
authors.forename: M C
authors.initials: MC
authors.lastname: Berndt
mesh_terms: D006493:Heparin / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D013921:Thrombocytopenia / Q000139:chemically induced*
chemical_list: D006493:Heparin