Antibodies to Heparin-Platelet Factor 4 Complex: Pathogenesis, Epidemiology, and Management of Heparin-Induced Thrombocytopenia in Hemodialysis

Heparin is the most common drug causing thrombocytopenia. There is an iceberg effect, with many more asymptomatic hemodialysis patients who develop antibodies to the heparin-PF4 complex compared with those who develop thrombocytopenia and then those who experience thrombotic complications, acute systemic reactions, and multiple thromboses. The diagnosis of HIT depends on clinical suspicion in combination with confirmatory laboratory tests; however, because none of the currently available tests have 100% sensitivity and/or specificity, the diagnosis is based on the clinical course and response to heparin therapy withdrawal. When HIT is suspected, heparin withdrawal is the key to management while awaiting laboratory test results, in combination with an alternative systemic anticoagulant. Although danaparoid has the greatest effect in terms of reducing platelet activation by antibodies to the heparin-PF4 complex, it has been superseded in North America by the direct thrombin inhibitors, in particular, argatroban. © 2009 National Kidney Foundation, Inc.