Lithium-enhanced radioactive iodine ablation of hyperthyroid patients

Abstract

Objective: The objective of this study was 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 iodine (RAI) ablation therapy. A total of 163 of the 185 hyperthyroid patients recruited completed the study. Cure was defined by achievement of euthyroidism or hypothyroidism.

Results: From of total of 163 patients, 75 received RAI alone and 88 received RAI with lithium. Those who received RAI with adjuvant lithium showed a higher cure rate (78.4%) compared with those who received RAI only (68.1%) (p = 0.002). At one month post RAI therapy, 27.4% of patients who received RAI with adjuvant therapy were cured. This finding showed a trend of being significant compared with just 14.5% cure rate in the group of patients who received RAI alone (p = 0.08). This is an indication of a faster cure rate for patients receiving RAI with lithium. Difference in mean T4 concentration at three months between RAI only (17.67 pmol/l) and RAI with lithium (11.55 pmol/l) was significant with a small size effect (U = 2328.5, Z = –2.700, p = 0.007, r = 0.01). A significant drop in T4 concentrations was observed between the baseline and one-month visit with small effect size (p = 0.001, r = 0.287) in patients who received both RAI and lithium.

Conclusion: Adjuvant lithium therapy increases the efficacy of radioactive iodine treatment in hyperthyroidism by increasing overall cure rate and also shortening the time to cure.

Keywords: hyperthyroidism, lithium, radioactive iodine ablation, thyroid stimulating hormone, thyroxine