Thyroid function and immunological activity during and after medical treatment of Graves' disease.

The variable clinical course of Graves' disease has been followed in 27 patients each studied for 2 years from the time of diagnosis. Thyroid hormone synthesis was blocked with large doses of antithyroid drugs for the first 12 months while euthyroidism was maintained with triiodothyronine. The latter was given alone from 12 to 18 months, and for the last 6 months the patients received no treatment. The activity of the disease was determined by repeated measurements of thyroid uptake of pertechnetate and by assay of thyrotrophin receptor antibodies (TSH binding inhibitory immunoglobulins). Retrospectively there were no features on presentation which singly or in combination indicated the clinical outcome: 16 patients remained in remission (Group 1) whilst in 11 hyperthyroidism had recurred before the end of the study (Group 2). Both measures of disease activity (thyroid uptake and antibody levels) fell during the first 12 months in patients of both groups. Recurrence of Graves' disease could be predicted in some but not all patients of Group 2 at 12 months by higher thyroid uptakes and levels of thyrotrophin receptor antibodies. There was, however, evidence of abnormal thyroid function, from which we infer continuing activity of the disease, 12 to 18 months after diagnosis in all patients of Group 1, even though these patients had normal TRH tests during the last phase of the study. The difference in the course of Graves' disease 12 to 24 months after diagnosis between those patients who remained in remission and those who did not was relative: in no patient was completely normal physiological control of thyroid function re-established. Clinical remission from hyperthyroidism at this time is a level of disease activity at which the normal physiological output of thyroid hormones is not exceeded.