SUN-430 A Prospective Clinical Trial on the Efficacy of Lithium as Adjuvant Therapy to Radioiodine in the Treatment of Hyperthyroidism (Railit Study)

Abstract

Background: Radioactive Iodine (RAI) is one of the main treatment modalities of hyperthyroidism. However, its success rate differs between centres. One of the determining factors of RAI success is its intrathyroidal persistence. Lithium has been said to improve efficacy of RAI but it remains debatable till today. Objective: To assess the efficacy and safety of lithium carbonate as an adjuvant therapy to RAI in the treatment of hyperthyroidism. Methods: This is a prospective, interventional, 2 arm parallel-group, open label single centre study carried out in the Endocrinology Unit, Department of Medicine and the Radionuclear Department of Penang General Hospital. The study period was from 30th August 2015 to 30thAugust 2016. The interventional medication is lithium carbonate 300mg twice daily for fourteen days starting on the day of RAI therapy. Lithium carbonate 300mg twice daily was given on the day of RAI (at least 2 hours prior to RAI) to 40 subjects and no added medication to the standard RAI therapy in 40 subjects in the control group. Subjects were followed up for 24 weeks with 6 study visits to assess side effects to medication, compliance to medication, determining cure with adjustments to medications as deemed needed by the study doctors during these study visits. There were 3 drop-outs in the RAI plus Lithium group and 2 drop-outs in the RAI alone group. Results: There were no significant difference in the clinical, demographic and biochemical profile of the two groups. Dose of RAI was a standard 15mCi in both groups. The cure rate in RAI plus lithium group was 62.2% and the cure rate in RAI alone group was 63.2% (p=0.932). Mean time to cure in RAI plus Lithium versus RAI alone group were similar 13.6±6.1weeks vs 13.2±6.5 weeks (p=0.841). There was numerically higher cure rate in Toxic Multinodular goitre in the RAI plus lithium group 10 out of 14 (71.3%) versus RAI alone group 8 out of 15 (53.3%)(P=0.316) though this was not statistically significant. Lithium however was able to prevent thyroid hormone surge 2 weeks post RAI as the median Free T4 was lower at week 2 post RAI compared to baseline (P=0.004) Conclusion: Lithium carbonate does not improve the efficacy of RAI significantly in hyperthyroid patients in our study. Its role in improving efficacy of RAI in toxic multinodular goitre needs further investigations. Lithium is able to prevent thyroid hormone surge post RAI therapy.