Antithyroid drug and Graves' hyperthyroidism. Significance of treatment duration and TRAb determination on lasting remission.

OBJECTIVE

To investigate the significance of treatment with antithyroid drugs longer than 12 months on lasting remission in Graves' hyperthyroid patients, and to study clinical and laboratory parameters of prognostic value.

PATIENTS

Fifty-two untreated Graves' hyperthyroid patients were assigned at random to two therapeutic groups. They were treated with carbimazole during 12 and 24 months in Group I (n = 28) and Group II (n = 24), respectively.

MEASUREMENTS

Serum levels of FT4, T3, sTSH and TSH receptor antibody (TRAb) were measured before starting treatment and at regular intervals during treatment and follow-up after drug withdrawal. We compared the relapse rate in both groups of patients, at short (2-yr) and long-term (5-yr) periods after drug withdrawal. Also, we compared clinical and biochemical parameters between patients who stayed in remission and who had relapse.

RESULTS

At the end of the short-term period, relapse had occurred in 13 (46.4%) Group I patients and in 13 (54.1%) Group II patients, p = 0.36. At the end of the long-term period, relapse had occurred in 24 (85.7%) Group I and 20 (83.3%) Group II patients, p = 0.78. No difference could be observed between patients who had stayed in remission and who had suffered relapse, within the 5-yr follow-up period regarding to goiter size, frequency of ophthalmopathy, TSH and TRAb levels.

CONCLUSIONS

The high relapse rate observed could be due to high iodine intake in our country. In this study and in a review of the available data, we have been unable to find any rational basis for courses of antithyroid drugs longer than twelve months for the treatment of Graves' hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)