Low- or High-Dose Radioiodine Remnant Ablation for Differentiated Thyroid Carcinoma: A Meta-Analysis

Context: There is uncertainty over the dose of I-131 required for thyroid remnant ablation. Most previous studies have been inadequately powered to establish the best fixed dose of I-131 for effective ablation. Objective: The aim of the study was to assess the effects of low- vs high-dose regimens of radio-iodine in thyroid remnant ablation for patients with differentiated thyroid carcinoma. Data Sources: Sources included the Cochrane Library, MEDLINE, EMBASE, and SCOPUS (all until September 2012). Study Selection: Randomized controlled trials that assess the efficacy of low- or high-dose of radioiodine ablation of thyroid remnants were collected. Data Extraction: Two authors performed the data extraction independently. Data Synthesis: Nine randomized controlled trials involving 2569 patients were included. The 1100-MBq vs the 3700-MBq radioiodine showed no statistically significant difference in successful thyroid remnant ablation (risk ratio [RR], 0.91 [0.79 to 1.04]; P = .15), both the 1100 vs the 1850 MBq (RR, 0.95 [0.83 to 1.10]; P = .52) and the 1850 vs the 3700 MBq (RR, 1.00 [0.85 to 1.17]; P = .98) also showed no significant differences (95% confidence intervals were calculated for each estimate). Also, no significant differences existed in quality-of-life scores on the SF-36 between different I-131-dose groups both on the day of ablation (RR, 0.15 [-0.65 to 0.96], P = .71; I-2 = 29%, P = .24) and 3 months after ablation (RR, - 1.1 [- 2.37 to 0.17], P = .09; I-2 = 22%, P = .26). A low dose of 1100 MBq radioiodine showed significant benefits in reducing adverse effects (total RR, 0.65 [0.55 to 0.77], P < .1; I-2 = 31%, P = .14) and shorter hospital isolation (RR, 0.4 [0.32 to 0.50]; P < .05). Conclusions: The low dose of 1100 MBq radioiodine activity is sufficient for thyroid remnant ablation as compared to 3700 MBq radioiodine activity with similar quality of life, less common adverse effects, and a shorter hospital stay. (J Clin Endocrinol Metab 98: 1353-1360, 2013)