Thyroid suppressibility: follow-up for two years after antithyroid treatment.

In hyperthyroidism suppression and non-suppression of early radioiodine neck uptake by exogenous thyroid hormone after a course of antithyroid drugs does not indicate clearly those patients who will eventually relapse or have a remission. Sixty-four hyperthyroid patients have been followed up for two years after an 18 to 24 months' course of carbimazole. Twenty-eight patients had suppressed at the end of the carbimazole course and 20 of these remained in remission for two years, and 36 were non-suppressed and 21 of these relapsed.Patients with the highest neck uptakes relapsed soonest after stopping treatment. Pronounced rebound occurred in neck uptakes at one month after stopping treatment, both in patients who relapsed and in those who remained in remission. By one year after stopping treatment those who remained in remission had shown a further fall in early neck uptake. In two patients who relapsed after exposure to stressful events no change in 20-minute radioiodine neck uptakes was found in relation to the supposed stress.