Safety from thromboembolism using intravenous immunoglobulin therapy in Kawasaki disease: Study of whole-blood viscosity

Background : High‐dose intravenous infusions of immunoglobulin (IVIG) are well established as a standard therapy for Kawasaki disease (KD) for reducing the risk of coronary artery aneurysms. IVIG therapy might increase the blood viscosity both in vitro and in vivo, which has been reported as a risk factor for cardiovascular or cerebrovascular thromboembolism in adults. Methods : We measured the whole‐blood viscosity in vitro, serum IgG and albumin, and blood hematocrit in 10 patients with KD and 10 with non‐KD (five with acute encephalitis, one with sepsis, one with idiopathic thrombocytopenic purpura, one with Guillain−Barré syndrome, one with insulin‐dependent diabetes mellitus, and one with Evans syndrome) before and after IVIG therapy. Results : The blood viscosity increased significantly after IVIG therapy in the patients with non‐KD, but did not increase in those with KD. Conclusion : The results of the present study suggest that the use of IVIG therapy for KD might be relatively safe, with no risk of thromboembolism due to hyperviscosity.