Endocrine Abstracts

Following the establishment of a telephone clinic follow-up for patients receiving radioiodine for recurrent thyrotoxicosis, we wished to further improve our results in achieving hypo(eu)thyroidism while minimising the risk of transient hyperthyroidism and thyroid storm post-therapy. Although not widely used, lithium has been shown to increase the effectiveness of radioiodine therapy, leading to prompter control of hyperthyroidism. Since August 2001, patients undergoing radioiodine therapy are prescribed lithium carbonate (Priadel) 800 milligrams daily for 3 days before treatment to be continued for a total of 10 days. Lithium levels are measured on the day of treatment, and 1 and 3 weeks post-radioiodine. We review the evidence for the adjunctive use of lithium in the treatment of thyrotoxicosis and present our preliminary experience and results. Results: 24 patients (4 male, 20 female) have received lithium carbonate as adjunctive treatment to radioiodine therapy (23 for Graves' disease and 1 for a toxic nodule). 5 patients have already had recurrence of thyrotoxicosis following previous radioiodine therapy. Mean dose of radioiodine given was 590 plus/minus 80 MegaBecquerels. Follow-up data ranges from 1-12 weeks. At the time of writing 14 patients (including all 4 male patients) have been rendered hypothyroid and have started thyroxine replacement. A further 7 patients are euthyroid off all medications and 3 patients have not yet had a long enough follow-up period to determine their thyroid hormone status. No patient has required treatment for recurrent thyrotoxocosis following this adjunctive treatment. Mean lithium levels were 0.6 millimoles per litre, 0.6 millimoles per litre and undetectable on the day of treatment, weeks 1 and 3 following treatment, respectively. No significant lithium toxicity was reported. Lithium therapy is a safe and effective means of controlling hyperthyroidism by preventing the release of organic iodine and thyroxine from the thyroid gland, and is a far more appropriate treatment than carbimazole in preparation for radioiodine treatment.