To investigate the iodine nutritional level of residents in iodine adequate areas in Henan Province, and provide basis for making policy of targeted guidance and rational iodine supplementation.

In the 156 counties of Henan Province in 2020, one township was selected from each location (east, west, south, north and middle) in each county; one school was selected from each township; 40 children aged 8-10 years in the school and 20 pregnant women in the township were selected to collect their urine and salt samples to test urine and salt iodine levels. One third of the counties were selected to examine the thyroid gland of children. Individuals lived in villages with water iodine between 40 and 100 μg/L were included in the study.

In iodine adequate areas, a total of 2 097 salt samples were collected from children and tested, the consumption rate of qualified iodized salt was 93.6% (1 962/2 097). A total of 2 096 urine samples were collected from children and tested, and the median urinary iodine was 288.0 μg/L. The goiter rate of children was 0.7% (5/723). A total of 1 068 salt samples from pregnant women were tested, and the consumption rate of qualified iodized salt was 93.0% (993/1 068). A total of 1 068 urine samples from pregnant women were tested, with a median urinary iodine 232.7 μg/L. Stratified by water iodine (40-59, 60-79, 80-100 μg/L), the median urinary iodine of children was 273.8, 288.6, and 305.9 μg/L, respectively, statistically significantly different between groups (H = 15.79, P < 0.001); the goiter rate of children was ≤2%, and the difference between groups was statistically significant (χ² = 7.31, P = 0.026); but the median urinary iodine of pregnant women was not significantly different (H = 1.82, P = 0.402). Under different water iodine conditions, there was no significant difference in urinary iodine levels in children and pregnant women between the high salt iodine concentration group (≥21 mg/kg) and the low salt iodine concentration group (< 21 mg/kg, P > 0.05).

The iodine nutrition level of children in iodine adequate areas in Henan Province is relatively high, and the iodine nutrition of pregnant women is appropriate. The goiter rate of children is at a relatively low level. Continuous surveillance should be conducted to comprehensively evaluate the iodine nutrition level. Various measures will be taken by regions and populations.

Iodine; Urine; Salts; Thyroid gland