Heparin-induced thrombocytopenia during renal replacement therapy.

There is increasing awareness that antibodies to heparin/platelet factor 4 complex can develop in both those with acute renal failure treated with continuous forms of renal replacement therapy and, to a lesser extent, regular hemodialysis patients. Clinical manifestations include premature clotting of the extracorporeal circuit and increased central venous thrombosis with indwelling venous dialysis catheters, associated with thrombocytopenia and increased platelet activation. Nevertheless, a minority of patients who develop heparin/platelet factor 4 antibodies do not have thrombocytopenia or thrombosis. When systemic anticoagulation is also required to treat venous thrombosis, then synthetic heparinoids or the direct thrombin inhibitors argatroban or recombinant hirudins are the agents of choice. Neither the synthetic heparinoids nor hirudin, however, are without their own problems, in that a minority of patients may have cross-reacting antibodies against the currently available heparinoids, and antibodies may similarly develop against recombinant hirudin, in this case leading to a potentiation of anticoagulant activity and increased risk of hemorrhage.