Comparing the effect of adjuvant lithium therapy on the afficacy of radioactive iodine therapy in hyperthyroidism
Hammond, Emmanuel Nii Boye
INTRODUCTION: Radioiodine ablation therapy with Iodine-131 (I-131) has been used in the treatment of hyperthyroidism for over 60 years. Lithium, a drug used in the treatment of psychiatric disorders is known to accumulate in the thyroid, increasing radioiodine retention by blocking its release and inhibiting thyroid hormone release without affecting thyroid iodine uptake. AIM: To compare the effect of adjuvant lithium therapy on the efficacy of radioactive iodine therapy in hyperthyroidism. Methods: This was a prospective simple randomised comparative, experimental cohort study of hyperthyroid patients for radioactive ablation therapy. Results: Amongst the 163 patients submitted for final analysis, 75 received RAI alone whilst 88 received RAI with Lithium. Those who received RAI with adjuvant lithium showed a higher cure rate (78.4%) compared to those who received RAI only (68.1%) (p = 0.002). At 1 month post RAI therapy, 27.4% of patients who received RAI with adjuvant therapy were cured compared to just 14.5% cure rate in those who received RAI alone, a trend of being statistically significant (p = 0.08) and indicating a faster cure rate for patients receiving RAI with lithium. Difference in mean T4 concentration at 3 months between RAI only (17.67pmol/l) and RAI with Lithium (11.55pmol/l) was significant with a small size effect (U = 2328.5, Z = -2.700, p = 0.007, r = 0.01). Also, decrease in T4 concentration from baseline to the 3 months visit in both groups were significant (p = 0.000 in both groups). However, significant drop in T4 concentrations were observed between the baseline and 1 month visit with small effect size (p = 0.001, r = 0.287) patients who received both RAI and lithium. CONCLUSION: Adjuvant lithium therapy increases efficacy of radioactive iodine treatment in hyperthyroidism by increasing overall cure rate and also shortening the time to cure.
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Medicine in Nuclear Medicine. Johannesburg, 2015