Heparin-induced thrombocytopenia |
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Authors: | B H Chong M C Berndt |
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Institution: | Haematology Department, St. George Hospital, Kogarah, New South Wales, Australia. |
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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. |
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