Iodine nutrition status of children 3-13 years of age in areas with high groundwater iodine content in China.

Abstract

Background: Adequate iodine status is crucial for children's health and normal development. However, there is a paucity of research on the iodine status of children from areas with high groundwater iodine content.

Objectives: To monitor the iodine status of children in Shandong, China (regions primarily characterized by high iodine concentrations in groundwater) and to describe the factors influencing children's iodine status.

Methods: A cross-sectional study was conducted from 2013 to 2023 on 3,253 children aged 3-13 years. We collected drinking water, spot urine, and 24-hour urine samples from children to assess their iodine status (measuring drinking water iodine concentration (WIC), water iodine intake (WII), urine iodine concentration (UIC), 24-hour urine iodine excretion (24-h UIE), daily iodine intake (DII), etc.), and analyzed influencing factors.

Results: The median WIC for children was 183 (IQR: 70.2, 362) μg/L, and the median spot UIC was 428 (IQR: 194, 737) μg/L, surpassing the WHO cutoff (300 μg/L). Children at risk of iodine excess numbered 1750 (61.8%). Approximately 61% of iodine intake came from drinking water. Boys had significantly higher iodine intake than girls (P < 0.001). Children's age showed positive correlations with spot UIC, 24-h UIC, and 24-h UIE. There were no significant differences in 24-h UIC and 24-h UIE among children with different BMIs. The logistic regression model revealed that the risk of iodine excess was increased by boy gender, increment in age (OR = 1.05, 95% CI: 1.02, 1.08), and every 10 μg (OR = 1.04, 95% CI: 1.03, 1.04) or 50 μg (OR = 1.19, 95% CI: 1.16, 1.22) increment in WII.

Conclusion: Children in areas with high groundwater iodine content are at a risk of iodine excess. As age increases, the risk of iodine excess in children rises, with boys at a higher risk than girls.