Iodine nutrition status of children in Henan Province after four years of implementation of the standard of "Definition and demarcation of water-borne iodine-excess areas and iodine-excess endemial areas" (GB/T 19380-2016) / 中华地方病学杂志

ABSTRACT

Objective:To investigate the iodine nutritional status of children and the consumption condition of non-iodized salt in Henan Province after implementation of the new standard of "Definition and demarcation of water-borne iodine-excess areas and iodine-excess endemial areas" (GB/T 19380-2016, hereinafter referred to as new standard) for four years (2021), and to provide a basis for scientific adjustment of intervention strategies.Methods:In 2021, according to the requirements of the new standard and based on the results of the water iodine survey in Henan Province from 2017 to 2020, a survey was conducted on the iodine nutrition status of children in water-borne high iodine areas in 47 counties (cities, districts, hereinafter referred to as counties) with high iodine administrative village (neighborhood committee, hereinafter referred to as administrative village). In each county, 5 administrative villages with median water iodine > 100 μg/L were selected as the investigation villages, and water samples were collected to determine the water iodine value. Forty non-boarding students aged 8 - 10 (age balanced, half male and half female, age increased to 6 - 12 when less than 40) were selected from each village as investigation subjects. Salt samples from their homes and urine samples were collected to detect salt iodine and urine iodine content, and thyroid volume of children was measured. And the monitoring results of areas where the supply of iodized salt had been suspended for less than 4 years (in newly high iodine areas) and more than 10 years (in previously high iodine areas) were further compared and analyzed.Results:A total of 257 administrative villages in the province were monitored, and the range of water iodine was 1.6 - 609.5 μg/L, with a median of 132.5 μg/L. A total of 8 611 children were tested for salt iodine, urine iodine and thyroid volume. The non-iodized salt rate was 58.3% (5 017/8 611), and the median urine iodine was 342.2 μg/L, thyroid enlargement rate was 2.9% (250/8 611). The median water iodine (153.0 vs 118.4 μg/L), the median urine iodine in children (371.6 vs 287.7 μg/L) and the goiter rate [3.8% (211/5 537) vs 1.3% (39/3 074)] in the newly high iodine areas were higher than those in the previously high iodine areas, and the differences were statistically significant ( Z = 583.12, - 14.09, P < 0.001; χ 2 = 44.40, P < 0.001); the non-iodized salt rate was lower than that of the previously high iodine areas [37.2% (2 057/5 537) vs 96.3% (2 960/3 074)], and the difference was statistically significant (χ 2 = 2 841.37, P < 0.001). Conclusions:The iodine nutrition level of children in water-borne high iodine areas of Henan Province in 2021 is at an excess level, but the non-iodized salt rate in residential households is low. We should make every effort to ensure the precise supply of non-iodized salt in high iodine areas after implementation of the new standard, and strengthen iodine nutrition monitoring and health education for key populations to prevent the occurrence of high iodine hazards.