(P29-025-23) No Association Between Iodine Intake and Thyroid Disease in Males: The Korean Genome and Epidemiology Study

Objectives: There are inconsistent conclusions about the association between iodine intake level and thyroid diseases in a population with high iodine intake. This study was conducted to evaluate the association between iodine intake and thyroid in male using data from the Korean Genome and Epidemiology Study.

Methods: Among a total of 68,613 Korean male subjects aged 40 years and over, 869 (1.27%) responded that they had been diagnosed with thyroid disease by a physician. Nutrient and iodine intakes were assessed using a validated semi-quantitative food frequency questionnaire. To determine the prevalence of thyroid disease according to iodine intake, logistic regression analysis was performed using the following two approaches: (1) subjects were divided according to quartile of iodine intake, after which odds ratios (ORs) and 95% confidence intervals (95% CIs) for thyroid disease were calculated according to iodine intake levels; (2) subjects were divided using the Korea dietary reference intakes (KDRIs) for iodine of the adult (EAR: 95 µg, RNI: 150 µg, UL: 2400 µg). Multivariate models were adjusted for age, body mass index, cohort, income level, education level, job, smoking, drinking, exercise, self-perceived health status, chronic diseases, and total energy intake (kcal/day). Statistical analyses were performed using SAS (version 9.4, SAS Institute, Cary, NC, USA), with p values < 0.05 indicating statistical significance.

Results: The median iodine intakes per day for the lowest and highest quartile groups were 40.9 µg, 548.0 µg respectively. The ORs (95% CIs) of the highest quartile in age-adjusted and multivariate model were 0.94 (0.79 - 1.13) and 0.89 (0.73 - 1.08), respectively (p for trend=0.9313 for age-adjusted model, p for trend=0.6416 for multivariate model).

Conclusions: Our cross-sectional results showed that high iodine intake was not associated with the prevalence of thyroid disease in Korean males. Further longitudinal studies are needed to examine the causal relationship in a population with high iodine intake.

Funding Sources: National Research Foundation, South Korea