Heparin-Induced Thrombocytopenia and Thrombosis

Heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT) are rare complications associated with use of unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH). HIT is a benign clinical condition characterized by a mild drop in platelet count with no clinical significance. HITT is an immune-mediated reaction associated with a widespread “hypercoagulable” state resulting in arterial and venous thrombosis. There is a higher incidence of HITT with UFH use than with LMWH use. Orthopedic surgery patients are at higher risk for developing HITT than are patients who receive prophylactic heparin for cardiovascular surgery or medical reasons. Therapy for patients suspected of having HITT should begin with immediate discontinuation of heparin in any form followed by pharmacologic inhibition with thrombin (eg, recombinant hirudin [lepirudin], argatroban, danaparoid sodium).