Efficacy of Dietitian-instructed Low Iodine Diet for Radioiodine Remnant Tissue Ablation for Thyroid Cancer.

ABSTRACT

We evaluated the significance of dietary instruction (DI) for patients who are going on a low iodine diet (LID) as a preparation for remnant tissue ablation for thyroid cancer. DI was done by a dietarian using a dedicated handbook we have developed. To assess the effect of LID on depleting body iodine, urinary iodine concentration (UIC) in patients with post-surgical papillary thyroid cancer was measured twice, before and after LID. UIC on the day of radioiodine administration was compared with radioiodine uptake (RU) in the remnant tissue. Additionally, the association between clinical and lifestyle-related features of patients and the outcome of LID were investigated. A questionnaire survey was conducted to determine whether the DI helped patients go on LID. The mean value of UIC after the one-week LID was decreased to about 15% of the baseline value. There was a significant inverse correlation between UIC and RU (r= -0.694). Age and UIC before the start of LID were linked to successful outcome of LID. In the questionnaire survey, 84% of the participants answered that the handbook helped them go on a LID. Likewise, 80% answered that they could manage their LID without using the boil-in-the-bag low iodine food. LID successfully decreased UIC in patients undergoing remnant tissue ablation. DI by a dietitian may make a practice of LID easier.