Radioiodine treatment of non-toxic multinodular goitre : effects of combination with lithium

Purpose: This study aimed to evaluate the effects of radioiodine ( 131I), alone or in combination with lithium, on thyroid volume and the prevention of radioiodine-induced thyrotoxicosis. This is the first clinical trial including only patients with multinodular goitre, normal TSH values and negative anti-thyroid auto-antibodies at baseline. Methods: Eighty consecutive patients were randomised to receive 131I plus lithium (group I+L) or 131I alone (group I). Thyroid ultrasonography and biochemical analyses were performed at baseline and at 1, 3, 6, 12 and 24 months after treatment. Results: At 1-4 weeks after treatment, 131I-induced hyperthyroidism was observed in 58.8% of patients and was prevented by lithium administration. A low incidence of hypothyroidism (19%) was recorded at 24 months, whereas up to 44% of patients developed anti-thyroid antibodies. A significant reduction in thyroid volume was observed after 131I, with a mean decrease of 47.2% (median 48.2%) at 24 months, without differences between the groups. Moreover, it was shown that the decrease in thyroid volume after 131I was also due to the significant shrinkage of thyroid nodules. Conclusion: This demonstrates that adjunctive lithium is able to reduce radioiodine-induced hyperthyroidism. Therefore, such treatment appears to be safe in older patients and those with underlying cardiovascular disease. In the present large series, 131I therapy was demonstrated to be highly effective in reducing thyroid and nodular volume even in patients treated with low 131I doses (2.5 MBq/ml of thyroid tissue), further supporting the view that radioiodine therapy represents a real alternative to surgery.