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Published on: October 12, 2012

Delayed-onset HIT caused by low-molecular-weight heparin manifesting during fondaparinux prophylaxis

Khalid A Alsaleh1, Sami M A Al-Nasser, Shannon M Bates

  • 1Department of Medicine, Michael G. DeGroote School of Medicine McMaster University, Hamilton, Ontario, Canada.

American Journal of Hematology
|September 23, 2008
PubMed

Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition caused by platelet-activating antibodies that react with platelet factor 4 (PF4)/heparin complexes. Delayed-onset HIT occurs after heparin is stopped. Fondaparinux, a synthetic pentasaccharide, is thought to be a safe alternative anticoagulant in HIT. We describe a patient with delayed-onset HIT triggered by low-molecular-weight heparin (LMWH) which occurred during fondaparinux prophylaxis and which was complicated by microangiopathic hemolytic anemia. Patient serum contained high-titer anti-PF4/heparin antibodies demonstrating heparin-dependent platelet activation with serial dilutions. Confirmed delayed-onset HIT with LMWH has not been previously reported. Low dose fondaparinux does not necessarily prevent thrombotic complications of HIT.

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