Radioactive iodine activities for postsurgical thyroid ablation: the lower the better.

the method of choice based on several reports [3–5] demonstrating equal efficacy of rhTSH compared to THW. rhTSH-assisted RAI ablative therapy is associated with similar rates of persistent disease and clinical recurrences than those observed after traditional THW preparation, at least in the short-term follow-up [6, 7] . In addition, preparation with either rhTSH or THW appears to have similar adjuvant effects on small-volume RAI-avid disease identified outside the thyroid bed at the time of initial RAI ablation [4, 8] . A still controversial issue is the choice of the radioiodine activity to be administered at the time of ablation. ATA [1] and ETA [2] guidelines (dated 2009 and 2006, respectively) recommend the use of 30to 100-mCi doses of radioiodine for low-risk patients and higher doses ( 1 100 mCi) for high-risk patients. However, such indications are not based on strong clinical evidence but rather on expert opinion derived mainly from retrospective uncontrolled studies. Only recently, two large prospective, randomized, multicenter studies, one in France [9] and one in the UK [10] simultaneously published in the New England Journal of Medicine, compared the results of thyroid ablation performed after THW versus rhTSH and using 30 versus 100 mCi. The initial treatment of differentiated thyroid cancer consists of total or near-total thyroidectomy. Surgery is usually followed by the administration of radioactive iodine activities (RAI) aimed to ablate any remnant thyroid tissue and potential microscopic residual tumor. It is still controversial whether this procedure may have an influence on the mortality rate, but in most series it seems to reduce the risk of regional recurrence and facilitates longterm surveillance based on serum thyroglobulin (Tg) measurement and diagnostic radioiodine whole body scan (WBS). According to several guidelines [1, 2] the recommendations for remnant thyroid ablation are modulated on the basis of risk factors. RAI ablation is indicated in high-risk patients (those with documented, or strongly suspected, residual disease), whereas it is not indicated in very low-risk patients (those with unifocal microcarcinomas, no metastases, and favorable histology). In patients at intermediate risk (those in between the low and high risk), remnant ablation may be indicated but the decision must be individualized. Effective thyroid ablation requires adequate stimulation by TSH. This may be achieved by thyroid hormone withdrawal (THW) or after recombinant human TSH (rhTSH) administration. The last procedure is considered Published online: December 13, 2012