Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
PLoS One. 2021 Sep 7;16(9):e0256727. doi: 10.1371/journal.pone.0256727. eCollection 2021.
Low-iodine diet (LID) is a crucial preparation for radioactive iodine (RAI) treatment or scan in thyroid cancer. The aim of this study is to analyze the influence of thyroid stimulating hormone (TSH) stimulation protocols and other clinical factors on LID adequacy. Thyroid cancer patients who underwent LID for RAI scan or treatment were retrospectively analyzed. Patients were guided to have LID for 2 weeks before RAI administration and urine iodine/creatinine ratio (UICR, μg/g Cr) was measured. TSH stimulation was conducted using either thyroid hormone withdrawal (THW) or recombinant human TSH (rhTSH) injection. Adequacy of LID was classified by UICR as 'excellent (< 50)', 'adequate (50-100)', 'inadequate (101-250)' and 'poor (> 250)'. A total of 1715 UICR measurements from 1054 patients were analyzed. UICR was significantly higher in case of rhTSH use than THW (72.4 ± 48.1 vs. 29.9 ± 45.8 μg/g Cr, P < 0.001). In patients who underwent LID twice using both TSH stimulation protocols alternately, UICR was higher in case of rhTSH than THW regardless of the order of method. Among clinical factors, female, old-age, and the first LID were significant factors to show higher UICR. Although the adequacy of LID was 'adequate' or 'excellent' in most patients, multivariate analysis demonstrated that THW method, male, young age, and prior LID-experience were significant determinants for achieving 'excellent' adequacy of LID. In conclusion, UICR was higher and the proportion of 'excellent' LID adequacy was lower with rhTSH than with THW. UICR was higher also in women, old-age, and LID-naïve patients. Further researches are required to suggest effective methods to reduce body iodine pool in case of rhTSH use and to validate the efficacy of such methods on outcomes of RAI treatment.
低碘饮食（LID）是甲状腺癌患者接受放射性碘（RAI）治疗或扫描前的重要准备。本研究旨在分析促甲状腺激素（TSH）刺激方案和其他临床因素对 LID 充分性的影响。回顾性分析了因 RAI 扫描或治疗而接受 LID 的甲状腺癌患者。患者在接受 RAI 治疗前 2 周接受 LID，并测量尿碘/肌酐比值（UICR，μg/g Cr）。TSH 刺激采用甲状腺激素撤退（THW）或重组人 TSH（rhTSH）注射。根据 UICR 将 LID 充分性分为“良好（<50）”、“充足（50-100）”、“不足（101-250）”和“不良（>250）”。分析了 1054 例患者的 1715 次 UICR 测量结果。rhTSH 组的 UICR 明显高于 THW 组（72.4±48.1 比 29.9±45.8μg/g Cr，P<0.001）。在使用两种 TSH 刺激方案交替进行两次 LID 的患者中，无论采用哪种方法的顺序，rhTSH 组的 UICR 均高于 THW 组。在临床因素中，女性、年龄较大和首次 LID 是 UICR 升高的显著因素。尽管大多数患者的 LID 充分性为“充足”或“良好”，但多因素分析表明，THW 方法、男性、年轻和既往 LID 经验是实现“良好”LID 充分性的显著决定因素。总之，与 THW 相比，rhTSH 组的 UICR 更高，“良好”LID 充分性的比例更低。女性、年龄较大和 LID 初治患者的 UICR 也较高。需要进一步研究以提出减少 rhTSH 应用时体内碘库的有效方法，并验证这些方法对 RAI 治疗结果的疗效。
