A Case of Heparin Induced Thrombocytopenia with Circulating Anti-PF4/Heparin Antibody

Heparin-induced thrombocytopenia (HIT) is usually caused by anti-platelet factor 4 (PF4)/heparin antibodies, leading to intravascular platelet activation. Circulating anti-PF4/heaprin antibody (IgG, IgA and IgM) was detected by ELISA (Asserachrom HPIA, Diagnostia Stago, Asnieres, France) in a 61-year-old man with coronary artery disease and dyspnea on exercise. He had undergone a coronoary angiography using 2,000 unit of heparin before a procedure. On admission, laboratory testing revealed a platelet count of 296×109/L and aPTT (activated partial thromboplastin time) of 38.1 sec. The fall in the platelet count was progressive, resulting in 42% and 53% of platelet counts on the 6th and 12th days after intravenous heparin administration, respectively. He was discharged after coronary artery bypass graft. On discharge, platelet count was normalized to be 212×109/L. On the 7th day after dischage, anti-PF4/heaprin antibody was detected by ELISA (Asserachrom HPIA, Diagnostia Stago, Asnieres, France).ope