Heparin-Induced Thrombocytopenia

A 63-year-old man with coronary artery disease who has recently undergone bypass surgery presents with dyspnea. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compared with 225,000 per cubic millimeter at the time of discharge nine days earlier. Findings on chest radiography are unremarkable; spiral computed tomography of the chest shows a pulmonary embolism. Heparin-induced thrombocytopenia is suspected. What diagnostic studies are warranted, and how should this patient be treated?