Relationship between water iodine and children's goiters

Excessive iodine can lead to goiters. However, the relationship between the water iodine concentration (WIC) and goiter rate (GR) is unclear. This study aims to explore the factors that influence children's GR in areas with high WIC and analyse the threshold value of the GR increase associated with the WIC. According to the monitoring of the areas with high WIC in China in 2018-2020, a total of 54 050 children in eight high water iodine provinces were chosen. Drinking water, urine and edible salt samples of children were collected. The thyroid volume (Tvol) was measured. A generalised additive model (GAM) was used to analyse the relationship between the WIC and GR in children. Among the 54 050 children in areas with high WIC, the overall GR was 3 center dot 34 %, the median of water iodine concentration was 127 center dot 0 mu g/l, the median of urinary iodine concentration was 318 mu g/l and the non-iodised salt coverage rate (NISCR) was 63 center dot 51 %. According to the GAM analysis results, water iodine and urinary iodine are factors that influence the Tvol and GR, while the NISCR affects only the GR. When the WIC was more than 420 mu g/l or the urinary iodine concentration was more than 800 mu g/l, the GR increased rapidly. When the NISCR reached more than 85 %, the GR was the lowest. Thus, in areas with high WIC, WIC more than 420 mu g/l may increase the risk of goiter, and the NISCR should be increased to over 85 % to avoid goiters in children.

Automated summary

In areas with high water iodine concentration, both water iodine and urinary iodine levels influence thyroid volume and goiter rate in children, while non-iodised salt coverage rate only affects the goiter rate. When the water iodine concentration exceeds 420 μg/l or urinary iodine concentration surpasses 800 μg/l, the goiter rate increases rapidly. Maintaining a non-iodised salt coverage rate of over 85% can help reduce the risk of goiter in children in high water iodine areas.