Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves’ disease

Objective Consuming a low-iodine diet (LID) is a widely accepted practice before administering radioiodine (131I) to evaluate and to treat thyroid disease. Although this procedure is well established for the management of patients with differentiated thyroid cancer, its use in patients with benign disease is unclear. So, we aimed to evaluate the influence of a LID on the outcome in patients with Graves’ disease (GD) treated with131I. Subjects and methods We evaluated 67 patients with GD who were divided into 2 groups: one group (n = 31) consumed a LID for 1-2 weeks, and the second group (n = 36) was instructed to maintain a regular diet (RD). Results The LID group experienced a 23% decrease in urinary iodine after 1 week on the diet and a significant 42% decrease after 2 weeks on the diet. The majority (53%) of the patients in the LID group had urinary iodine levels that were consistent with deficient iodine intake. However, there was no difference in the rate of hyperthyroidism’s cure between the LID and the RD groups 6 months after 131I therapy. Furthermore, the therapeutic efficacy did not differ in patients with varying degrees of sufficient iodine intake (corresponding urinary iodine levels: 30 μg/dL is excessive). Conclusion In the present study, we demonstrated that although a LID decreased urinary iodine levels, those levels corresponding with sufficient or a mild excess in iodine intake did not compromise the therapeutic efficacy of131I for the treatment of GD.

研究目的：在采用放射性碘(131I)评估与治疗甲状腺疾病前，低碘饮食（low-iodine diet, LID）是一项被广泛认可的临床操作。尽管该流程在分化型甲状腺癌患者的诊疗管理中已较为成熟，但其在良性甲状腺疾病患者中的应用价值仍不明确。本研究旨在评估低碘饮食对131I治疗格雷夫斯病（Graves’ disease, GD）患者预后的影响。

研究对象与方法：本研究共纳入67例GD患者，将其分为两组：试验组（n=31）接受为期1~2周的低碘饮食，对照组（n=36）则保持常规饮食（regular diet, RD）。

研究结果：低碘饮食组患者在开始饮食干预1周后，尿碘水平下降23%；饮食干预2周后，尿碘水平显著下降42%。低碘饮食组中53%的患者尿碘水平符合碘摄入不足的判定标准。然而，在131I治疗6个月后，低碘饮食组与常规饮食组的甲状腺功能亢进治愈率并无显著差异。此外，在不同碘摄入充足程度（对应尿碘水平：30μg/dL为过量）的亚组中，治疗疗效亦无明显差异。

研究结论：本研究证实，尽管低碘饮食可降低患者尿碘水平，但对于碘摄入充足或轻度过量的GD患者而言，低碘饮食并未削弱131I治疗的临床疗效。