Relapses after thionamide therapy for Graves' disease.

Between 1969 and 1979 a course of either propylthiouracil or carbimazole was given to 102 patients with Graves' disease. Ten of the patients discontinued the therapy because of adverse reactions or persisting symptoms, and 40 relapsed at some time after cessation of the therapy, giving a proportion of total failures of 49%. The proportion of such failures increased from 45% in 1969-72 to 57% in 1973-79. The probability of relapse was significantly higher in 1973-79 than in the earlier period (p less than 0.01). Patients aged 30-39 years had the highest proportion of failures (55%), but the mean time until relapse (6 months) was shortest in patients older than that. Adverse reactions--agranulocytosis, leukopenia, urticaria and elevated serum levels of liver enzymes--were seen in 12 patients. Six patients developed hypothyroidism after a mean time of 3.5 years after termination of thionamide therapy.