Thyroxine suppression therapy in Graves' disease

Abstract

A recent Japanese report of a novel ‘block-and-replace’ regime for Graves' hyperthyroidism in which thyroxine was continued alone after the combination therapy was stopped was associated with a negligible relapse rate of less than 2%. Such a finding has the potential to revolutionize the management of Graves' disease but a similarly large study from Scotland failed to confirm any benefit from the new treatment. Apart from obvious differences in race and dietary iodine there is no adequate explanation for the discrepant results. In all studies reporting a fall in thyrotropin (TSH) receptor antibodies (TRAb) and/or relapse rates following conventional or novel ‘block-and-replace’ regimes, serum TSH concentrations were often elevated in the control groups treated with antithyroid drugs alone. Theoretically, this could lead to continued expression of thyroid cell surface antigen, increased production of TRAb and an adverse effect on remission rates. This, however, fails to explain the extraordinary low remission rates of the original study from Japan and, in the meantime, there is no good reason to adopt the novel regime, at least in Caucasians.