title: The Impact of Low Adherence to the Low-iodine Diet on the Efficacy of the Radioactive Iodine Ablation Therapy.
abstract: To improve the efficacy of radioactive iodine (RAI) therapy for differentiated thyroid cancer patients, a low-iodine diet (LID) prior to the therapy is recommended. In iodine-rich areas such as Korea, however, a strict LID is very difficult to maintain. We experienced the cases of three patients showing low adherence to the LID before initial RAI therapy, and analyzed the main food source supplying iodine during the LID, and examined the influence of the poorly maintained LID on the efficacy of RAI therapy. The dietary intake during the LID periods were assessed using three-day dietary records and remnant thyroid activity after the second RAI administration was also evaluated. All patients' mean daily iodine intake during two-week LID periods exceeded the 100 µg guideline set by the Korean Thyroid Association (median 110.9 µg, ranges 100.4-117.0 µg). Although the typical food sources of iodine intake are seaweeds in Korea, salted vegetables were the main contributor to the patients' iodine intake during the LID periods. Remnant thyroid activity was shown on a follow-up scan in all of 3 patients suggesting low efficacy of RAI therapy. In summary, the patients with low adherence to the LID guideline showed unsuccessful remnant ablation, and the main food source of iodine was salted vegetables. Further studies are necessary to examine the relationship between adherence of the LID and RAI efficacy according to dietary iodine intake levels, as well as food sources that cause low adherence to the LID. These data can then be used to develop more practical LID guidelines.
authors.affiliation: Department of Food Service and Nutrition Care, Seoul National University Hospital, Seoul 03080, Korea. ; Department of Food and Nutrition, Seoul National University, Seoul 08826, Korea.
authors.forename: Dal Lae
authors.initials: DL
authors.lastname: Ju
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Young Joo
authors.initials: YJ
authors.lastname: Park
authors.affiliation: Department of Food and Nutrition, Seoul National University, Seoul 08826, Korea.
authors.forename: Hee-Young
authors.initials: HY
authors.lastname: Paik
authors.affiliation: Major of Food and Nutrition, School of Human Ecology, The Catholic University of Korea, Bucheon 14662, Korea.
authors.forename: YoonJu
authors.initials: Y
authors.lastname: Song
keywords: Dietary management; Iodine; Patient adherence; Radioactive isotopes; Thyroid cancer