Thrombotic complications after intravenous immunoglobulin therapy in two patients

Although intravenous immunoglobulin (IVIg) generally is considered a safe treatment for various autoimmune and inflammatory disorders, rare cases of thrombosis may occur. We describe two patients who experienced thrombotic complications associated with IVIg therapy. A 54-year-old woman with idiopathic thrombocytopenia received IVIg 1 g/kg/day for 2 days. While receiving her infusion on day 2, she had an ischemic stroke with hemiparesis; 3 days later she developed deep vein thrombosis. A 33-year-old woman with Evans' syndrome received IVIg 400 mg/kg/day for 5 days and developed deep vein thrombosis 1 week after therapy was completed; she then received warfarin. Six months later, she received an additional course of IVIg for recurrent hemolytic anemia; 1 day later she died of pulmonary thromboembolism. We suggest that IVIg may promote thrombosis by increasing blood viscosity, activating platelets, or causing vasospasm and should be administered with caution.