Short-term antithyroid drug therapy for the thyrotoxicosis of Graves's disease.

We investigated whether thyrotoxic patients treated with short-term antithyroid therapy would achieve prolonged remissions. Thirty-one previously untreated and nine previously treated patients with thyrotoxic Graves's disease received a single daily dose of methimazole or propylthiouracil. The drug was stopped at, or shortly after, the time they became euthyroid. Twelve of the 31 previously untreated patients remained in remission for 29 +/- 3.5 months (mean +/- S.E.) after treatment for 4.5 +/- 0.3 months. Four of the nine previously treated have remained in remission of 13.0 +/- 2.1 months after treatment for 3.0 +/- 0.3 months. Of various possibilities analyzed, only a small goiter at the onset of therapy and tri-iodothyronine toxicosis were significantly favorable prognostic indicators that a remission would be maintained. The lasting remission rate is as good when antithyroid drugs are stopped as soon as the patient is euthyroid as when they are continued for one year or more.