Efficacy of Different Protocols of Radioiodine Therapy for Treatment of Toxic Nodular Goiter: Systematic Review and Meta-Analysis of the Literature

CONTEXT: To evaluate treatment success and hypothyroidism following main methods of radioiodine therapy of toxic nodular goiter (TNG); calculated versus fixed dose and high versus low dose of radioiodine. EVIDENCE ACQUISITIONS: We searched MEDLINE and SCOPUS databases from inception till July 2013, for clinical trials that compared two different methods of radioiodine administration in TNG. The trials were classified into two groups, those that compared fixed versus calculated dosimetry method and those that assessed high fixed dose versus low fixed dose method. Treatment response was defined as euthyroidism or hypothyroidism, one year after radioiodine administration. We calculated the risk ratio and risk difference of treatment response as well as permanent hypothyroidism as outcome variables. Random effects model was used for data pooling. RESULTS: The literature search yielded 2538 articles. Two randomized and five non-randomized clinical trials with 669 patients met the eligibility criteria for the meta-analysis. Patients with TNG who were treated according to the calculated method had 9.6% higher cure rate (risk ratio=1.17) and only 0.3% more permanent hypothyroidism compared to patients treated with the fixed dose method. There was no significant difference in the amount of administered radio-iodine in the two groups. Patients treated with fixed high dose had 18.1% more cure rate (risk ratio = 1.2) and 23.9% more permanent hypothyroidism (risk ratio = 2.40) compared to patients treated by fixed low dose protocols. CONCLUSIONS: Calculated radioiodine therapy may be preferred to fixed dose method in patients with TNG. High dose methods are associated with more response and more hypothyroidism.