Adjuvant lithium improves the efficacy of radioactive iodine treatment in Graves' and toxic nodular disease

Abstract

SummaryContext Lithium increases iodine retention in the thyroid gland and inhibits thyroid hormone release. Although lithium has been reported to improve the efficacy of radioactive iodine (RAI) treatment in Graves' disease, its role as an adjunct to RAI treatment of hyperthyroidism, particularly in toxic nodular disease, remains contentious. Objective To assess whether adjuvant lithium increases the efficacy of a fixed dose RAI regimen in Graves' and toxic nodular hyperthyroid patients. Design and setting Retrospective cohort study in a tertiary referral centre. Two hundred and four hyperthyroid patients (163 Graves' disease, 26 toxic multinodular goitre and 15 solitary toxic thyroid adenoma). Intervention One hundred and three patients received RAI alone (median dose 558 MBq). One hundred and one patients received RAI (median dose 571 MBq) with adjuvant lithium (800 mg/day for 10 days). Main outcome measure Proportion of patients cured at any time over a 1-year period following RAI treatment. Cure was defined as sustained (two or more sequential time points) biochemical euthyroidism or hypothyroidism during the follow-up period.Results The likelihood of cure at any time was 60% greater in all hyperthyroid patients (Graves' plus toxic nodular disease) receiving adjuvant lithium (n = 204, P = 0·003). In patients with Graves' disease receiving RAI + lithium, there was a similar occurrence in cure (n = 163, P = 0·006). Cure was twice as likely in patients with toxic nodular (non-Graves') disease receiving RAI + lithium compared with RAI alone (n = 41, P = 0·01). Conclusions This study supports the use of adjuvant lithium to improve the efficacy of RAI in the treatment of Grave's disease and suggests a novel role in the management of toxic nodular (non-Graves') disease.

Lithium-enhanced radioactive iodine ablation of hyperthyroid patients

“…Lithium treatment resulted in an additional 22.4% increase in cure rate three months post RAI therapy. Our findings are comparable to those from Martin et al, the Pisa group and Zha et al 7,11,18,19 The lower proportions of cure rate observed in our study compared with those from Martin et al and the two studies from the Pisa group can be attributed to the shorter end point of three months in our study compared with at least one year in the others. It is noteworthy that our findings differed from that of Bal et al, who found no difference between the RAI only group and RAI with adjuvant lithium group 20 with cure rates of 68.4% and 68.9% respectively.…”

“…Our findings were in agreement with those of Martin et al and the Pisa group who both found a significant reduction in time to cure in their studies. 7,18 A later study by the Pisa group also supported our results as they found that 50% of patients who received adjuvant lithium were cured in two months compared with the RAI only group, which had 50% cured in three months. 11 This prompter control of hyperthyroidism is likely due to the fact that release of organic iodine as well as thyroid hormones is blocked by lithium without affecting radioactive iodine uptake (RAIU) by the gland.…”

“…2 The cure rates achieved in our study (56% for RAI only and 78.4% in those receiving RAI with adjuvant lithium) were found to be generally lower compared with those achieved in similar studies, which had cure rates greater than 80%. 7,11,18,19 This, however, can be explained by the fact that our study had a shorter endpoint of three months post RAI therapy in comparison with the other studies where follow-up lasted at least a year post-therapy. We defined cure in our study using TSH values.…”

“…The dose also corresponded with that given by Martin et al, except that they gave lithium for 10 days starting three days before RAI therapy. 18 Our shorter protocol hoped to avoid increasing hospital visits, as one of our objectives was not to interfere with the regular existing hospital visits and protocols.…”

“…The increased cure rate in nodular patients, however, is corroborated by Martin et al, who showed that adjuvant lithium doubled the chance of cure with RAI therapy. 18 For these patients in particular, this finding is very important as nodular disease patients generally have lower cure rates and a higher likelihood for retreatment compared with Graves' patients. 2 The cure rates achieved in our study (56% for RAI only and 78.4% in those receiving RAI with adjuvant lithium) were found to be generally lower compared with those achieved in similar studies, which had cure rates greater than 80%.…”