Thyroid volume reduction following radioiodine therapy in patients with autonomous goitre and Graves' disease

Aim: It is well known that radioiodine therapy (RITh) leads to a significant thyroid volume reduction (TVR). But until now only little data has been presented due to the course of time and the extent of TVR. Method: Therefore the data of 33 patients with Graves' disease IGD), 36 patients with multifocal (MAG) and 31 with solitary (SAG) autonomous goitre were analyzed retrospectively Results: All the patients showed a highly significant (p <0.001) TVR, which continued up to 1 year after RITh. Receiving equal effective radiation doses, the extent of TVR was significantly greater for GD than for MAG. This difference developed within six weeks up to 3 months after RITh. Conclusion: This observation suggests that the underlying thyroid disease affects the therapeutic effect of RITh and may be partially explained by the total suppression of non-autonomous thyroid tissue in AG at the time of RITh. In patients with SAG with a 1.7 times higher effective radiation dose than in MAG relative TVR was about 1.6 times stronger in SAG than in MAG. This demonstrates a direct relation between the effective radiation dose and the extent of the TVR after RITh.