Heparin-induced thrombocytopenia.
There are two types of heparin-induced thrombocytopenia. Type I is more common, has an early onset, and is mild, transient, and benign. Type I is due to direct heparin-induced platelet aggregation and is rarely associated with thromboembolic sequela. Type II is infrequent, has a late onset, and is more severe. Type II is due to an immune-mediated platelet aggregation caused by IgG and IgM that becomes bound to platelets. In Type II, the antibody titers decline over several months; however, early reexposure can result in a catastrophic secondary immune response. Frequently, Type II is associated with life- or limb-threatening thromboembolic complications (white clots), including stroke.
Becker
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PS
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2182.
Miller
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VT
D002561:Cerebrovascular Disorders / Q000209:etiology; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects / Q000276:immunology; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced* / Q000276:immunology / Q000628:therapy; D013923:Thromboembolism / Q000209:etiology
D006493:Heparin