A second group of 22 patients who had Graves’ disease for more than 5 years and did not receive preventive steroid therapy represented the control group. The patients were followed in the clinic for up to 5 years after the radioactive iodine therapy.
In the preventive steroid group, none of the patients developed new thyroid eye disease or had thyroid eye disease reactivation within 6 months after the radioactive iodine therapy. Oral and IV steroid treatment had the same effect in preventing thyroid eye disease. Two patients with preexisting thyroid eye disease (1 patient received oral steroid and 1 patient received IV steroid treatment) reactivated at 12 and 20 months, respectively; the reactivation was thought to be related to the natural course of the disease rather than the radioactive iodine therapy itself. In the control group, none of the patients developed new thyroid eye disease, and only 1 patient had thyroid eye disease reactivation 3 months after the radioactive iodine therapy. This patient developed severe hypothyroidism at that time, and the thyroid eye disease improved when thyroid levels normalized on thyroid hormone treatment.
More than 80% of the patients who answered the sideeffects questionnaire reported symptoms possibly related to steroid therapy (weight gain, dyspepsia, fatigue, mood disorder, etc.); those treated with oral steroids were more likely to develop symptoms as compared with those who received IV steroids.
Serum TRAb levels, the cause of Graves’ disease and which are thought to play a major role in development of thyroid eye disease, increased as expected in all groups after the radioactive iodine therapy; however, it showed a delayed rise in steroid-treated patients with a peak at 6 months instead of 3 months in patients who did not receive this treatment. The duration of Graves’ disease, serum TRAb titers, and steroid use did not affect the effectiveness of the radioactive iodine therapy in treating the hyperthyroidism.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study suggests that steroid treatment can prevent thyroid eye disease induced by radioactive iodine therapy in patients with Graves’ disease for less than 5 years. Steroid therapy might not be necessary in patients who had Graves’ disease for more than 5 years, since their risk of new or reactivated thyroid eye disease related to the radioactive iodine therapy is extremely low. The known increase in serum TRAb levels following radioactive iodine therapy is delayed by steroid treatment, which likely plays a role in the thyroid eye disease benefit noted from this treatment.
— Alina Gavrila, MD, MMSC