Heparin-induced thrombocytopenia occurring after discontinuation of heparin.

BACKGROUND Heparin-induced thrombocytopenia is caused by antibody formation to heparin-platelet factor 4 complexes. It typically develops 5 to 14 days after the initiation of heparin, but it can occur up to 3 weeks after the patient stops taking it. Early recognition by monitoring platelet counts during heparin therapy can decrease associated mortality and morbidity. METHODS A case is described of a patient with severe morbidity as a result of heparin-induced thrombocytopenia. The medical literature was searched using the key words "heparin/adverse effects" and "thrombocytopenia." RESULTS AND CONCLUSIONS The severe morbidity and potential mortality associated with heparin-induced thrombocytopenia are caused mainly by thrombosis. If it is suspected, all heparin products should be immediately stopped. Platelet counts usually return to normal after the heparin is discontinued. Approximately 50% of patients with heparin-induced thrombocytopenia develop thrombotic events. Patients should receive anticoagulation with agents other than heparin or low molecular weight heparin. As early detection of heparin-induced thrombocytopenia seems to improve outcome, it is recommended that all patients on heparin should have frequent monitoring of platelet counts.