Iodine status and characteristics of Korean adolescents and their parents based on urinary iodine concentration: a nationwide cross-sectional study

Abstract

Purpose Iodine is a major component of thyroid hormones. Both deficiency and excess of iodine are major risk factors for thyroid disease, making it important to accurately assess iodine level in the human body. Urinary iodine concentration (UIC) is a commonly used measure of iodine status. However, there is little research on iodine status and related characteristics in Korean adolescents. Methods Using data from the sixth Korea National Health and Nutrition Examination Survey (KNHANES VI) for the years 2013–2015, we analyzed UIC and thyroid function test results in adolescents aged 10–18 years and their parents. We also investigated the influence of socioeconomic factors and family history of thyroid disease on iodine status. Results Mean UIC in Korean adolescents was 963.5±55.7 μg/L. Among evaluated subjects, 6.6%±1.0%, 29.8%±1.7%, and 63.9%±1.9% had low (UIC<100 μg/L), adequate (UIC: 100–299.9 μg/L), and excess (UIC≥300 μg/L) iodine concentrations, respectively. Based on regional trends, the incidence of iodine deficiency exceeded 10% in several regions, even though there was a dominance of regions with excess iodine. Parental UIC, female sex, average monthly income, and expenditure were all found to affect the iodine status of Korean adolescents. Conclusions Although regional differences exist, the iodine status in Korean adolescents is mainly affected by the eating habits of their families and socioeconomic factors. Therefore, monitoring of iodine status is necessary in this population.

Update on Thyroid Hormone Levels and Thyroid Dysfunction in the Korean Population Based on Data from the Korea National Health and Nutrition Examination Survey VI (2013 to 2015)

“…This trend is consistent with the findings of previous studies [20,21]. Choi et al [22] analyzed UIC in adolescents aged 10 to 18 years and their parents using the KNHANES VI. They reported that the prevalence of iodine deficiency exceeded 10% in several regions of Korea, and that iodine intake status in Korean adolescents was primarily affected by their families' eating habits and household income.…”

Relationship of iodine excess with thyroid function in 6-year-old children living in an iodine-replete area

“…Higher UIC levels in boys than in girls may result from higher consumption of iodine-rich food and higher energy intake in boys ( 21 ). Considering the absence of sex differences in Cr-adjusted iodine variables, sex differences in UIC may be due to differences in urine volume or hydration status ( 12 , 17 ).…”

“…South Korea is an iodine-replete area ( 10 ) characterized by high seaweed consumption ( 11 ). According to the 2013–2015 Korean National Health and Nutrition Examination Survey, a high prevalence (64.9%) of iodine excess has been reported in Korean children and adolescents ( 8 , 12 ).…”

Thyroid nodules in childhood‐onset Hashimoto's thyroiditis: Frequency, risk factors, follow‐up course and genetic alterations of thyroid cancer

“…In childhood‐onset HT patients, the prevalence of thyroid nodules/cancers varies according to the country's iodine status 9‐14 . South Korea is an iodine‐sufficient country, and a nationwide survey indicated iodine excess in ~64.9% of the paediatric population 15,16 . Although the direct effects of iodine excess on PTC development remain unclear, it is well established that iodine excess can increase the risk of hypothyroidism in patients with thyroid autoimmunity 17 .…”