MORE ON LOW VS HIGH DOSE 131-I ABLATION

Low- or high-dose radioiodine remnant ablation for differentiated thyroid carcinoma: a meta-analysis. Cheng W, Ma C, Fu H, Li J, Chen S, Wu S, Wang H. J Clin Endocrinol Metab. 2013 Apr;98(4):1353-60. doi: 10.1210/jc.2012-3682.
There is uncertainty over the dose of (131)I required for thyroid remnant ablation.: The aim of this study was to assess the effects of low- vs high-dose regimens of radioiodine in thyroid remnant ablation for patients with differentiated thyroid carcinoma. Randomized controlled trials that assess the efficacy of low- or high-dose of radioiodine ablation of thyroid remnants were collected. Nine randomized controlled trials involving 2569 patients were included.
The 1100-MBq (30mCi) vs the 3700-MBq (100mCi) radioiodine dose 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 (131)I-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. COMMENT- In a meta-analysisinvolving a large number of subjects, use of lower 131-I doses for post-operative ablation was as effective as 100mCi doses,  and with fewer undesirable side-effects. (L De Groot, MD)