Timing of Hormone Withdrawal in Children Undergoing ¹³¹I Whole-Body Scans for Thyroid Cancer

Abstract

Background: Little objective pediatric data exist to guide the optimal time needed to achieve thyroid-stimulating hormone (TSH) levels ≥30 μIU/mL prior to performing ¹³¹I or ¹²³I whole-body scan (WBS) imaging in children with thyroid cancer in the post-thyroidectomy period or after hormone discontinuation. Methods: Retrospective study of patients aged 5-19 years who underwent WBS. Patient data collection included type and duration of withdrawal (liothyronine [L-T3], levothyroxine [L-T4], or post-thyroidectomy status without hormonal replacement) and TSH measured prior to WBS (level and timing). Results: A total of 175 TSH level measurements were performed in 68 patients. Thirty-five TSH values were obtained 2-7 weeks postoperatively and 101 values were obtained 2-8 weeks post L-T4 withdrawal. One patient in each group had a TSH level <30 μIU/mL. There was no difference in TSH levels between 3 weeks and 4 weeks postoperatively (p = 0.14) or post L-T4 cessation (p = 0.21). Thirty-nine TSH measurements were obtained 1-28 days post L-T3 withdrawal. Three patients had to be rescheduled due to inadequate TSH levels, including one after 14 days L-T3 withdrawal. Conclusion: TSH levels ≥30 μIU/mL were achieved at 3 weeks post thyroidectomy or after L-T4 withdrawal and after at least 2 weeks following L-T3 cessation.

Recombinant human thyrotropin in radioiodine diagnostics and radioiodine ablation of patients with well-differentiated thyroid cancer: the first experience in Russia

“…Для обеспечения высокого захвата йода остаточной тиреоидной тканью, которая в том или ином количестве всегда остается после хирургического удаления органа, а также опухолевыми клетками высокодифференцированной карциномы щитовидной железы, чаще всего сохраняющими йоднакопительную способность, необходимо обеспечить уровень ТТГ в крови более 30 мМЕ/мл [4,5]. Традиционным методом подготовки пациентов к радиойоддиагностике (РЙД) и радиойодблации (РЙА) является эндогенная стимуляция синтеза ТТГ посредством отмены левотироксина натрия на срок 3-4 нед (у взрослых -на 4 нед, у детей -на 3 нед) [6].…”