Changes in graves' ophthalmopathy after radioiodine and anti-thyroid drug treatment of Graves' disease from 2 prospective, randomized, open-label, blinded end point studies

Abstract

Aims: A significant association between radioiodine therapy (RIT) and the development or the worsening of pre-existing Graves' ophthalmopathy (GO) has been reported. This post-hoc analysis of 2 studies attempted to describe the changes observed in pre-existing or new-onset GO following RIT with the goal of euthyroidism rather than hypothyroidism and to describe the relationship GO changes and the final outcome.

Patients and methods: In 2 prospective, randomized open-label blinded endpoint trials, patients received radioiodine alone; or, patients received radioiodine or antithyroid drug therapy (ATD). The severity and activity of GO were assessed during a 9-12-year follow-up. The study end points in study 1 were euthyroidism, hyperthyroidism, hypothyroidism, and changes in GO. In study 2, the end points were euthyroidism, hyperthyroidism, hypothyroidism, relapse, and changes in GO.

Results: Both RIT and ATD were associated with worsening GO and new-onset GO. Both RIT and ATD led to similar aggravation of pre-existing GO or the development to new-onset GO. After RIT or ATD, the euthyroid patients (without levothyroxine substitution) demonstrated an improvement in GO, with 78-89% patients with preexisting GO exhibiting improvement, whereas hyperthyroid, hypothyroid and relapsed patients had worsening or new-onset GO.

Conclusions: Thyroid function is a dominant risk factor. Thyroid function may be the most important determinant in worsening or new-onset GO in both the natural disease course and in treated patients, independent of the kind of treatment. Therefore, we recommend euthyroidism as a goal of treatment.