Time, carbimazole and the outcome of Graves' disease.

A detailed comparison was made over 18 months of the serial mean 20 min 132I uptake behavior between 15 Graves' disease patients whose hyperthyroidism ultimately remitted (Group E) and 20 in whom it persisted (Group R). All were treated with carbimazole and T3. There were not qualitative differences in uptake between the 2 groups. In both, the uptake fell with time, and the slopes were parallel. The fact that the mean uptake started lower in Group E patients was sufficient to explain why it became normal much earlier than that of Group R, which had not normalized by 18 months. In both groups, over half the overall fall in uptake occurred during the first month of treatment with carbimazole. We conclude that, while time remains the most important determinant of outcome in Graves' disease, some possible immunosuppressive action of carbimazole can shorten the cycle length to a major degree.