Similar efficacy for rhTSH and levothyroxine withdrawal, as preparation for thyroid ablation

Pacini F et al. (2006) Radioiodine ablation of thyroid remnants after preparation with recombinant human thyrotropin in differentiated thyroid carcinoma: results of an international, randomized, controlled study. J Clin Endocrinol Metab 91: 926–932

¹³¹I ablation of remnant thyroid tissue is undertaken following thyroidectomy for thyroid carcinoma to prevent tumor recurrence and improve the accuracy of follow-up screening. The current practice of levothyroxine withdrawal before ablation stimulates endogenous TSH, which improves ¹³¹I uptake, but also causes hypothyroid symptoms that markedly reduce patients' quality of life. Preablation administration of recombinant human TSH (rhTSH) could obviate the need for levothyroxine withdrawal, but there are concerns that the subsequent ablation procedure might not be as successful in patients given rhTSH.

Pacini et al.'s multinational, randomized trial showed that rhTSH and levothyroxine withdrawal had comparable efficacy as preparation for thyroid-remnant ablation (successful ablation was defined as fractional uptake of ¹³¹I in the thyroid bed <0.1%, or rhTSH-stimulated serum thyroglobulin level <2 ng/ml at 8 months after ablation). Of 63 patients scheduled to undergo preparation for post-thyroidectomy ablation, 30 were randomly allocated to undergo levothyroxine withdrawal and 33 to receive rhTSH.

Although there was no statistically significant difference between the groups in terms of ablation success, patients who received rhTSH reported markedly higher quality of life scores both before and after ablation, and also received a markedly lower radiation dose to the blood than those who underwent levothyroxine withdrawal. Use of rhTSH as preparation for post-thyroidectomy ablation is effective and represents an attractive treatment option, say Pacini et al.