To investigate the iodine nutrition levels of children aged 8 - 10 and pregnant women in iodine deficient areas and iodine adequate areas of Inner Mongolia Autonomous Region (Inner Mongolia for short), and to provide scientific basis for prevention and treatment of iodine deficiency disorders.

From March to July 2022, iodine nutrition analysis was conducted in iodine deficient areas and iodine adequate areas of 104 banners (counties, cities and districts) in 12 league cities in Inner Mongolia. Each monitoring banner (county, city and district) was divided into five sampling areas by east, west, south, north, and center, with one Sumu (township, street) selected from each area. One primary school was selected from each Sumu (township, street), and 40 non-boarding students aged 8 - 10 were selected from each primary school. One third of the students underwent thyroid ultrasound examination. Twenty pregnant women were selected from each of the 5 Sumus (townships, streets) in each monitoring banner (county, city and district). Household salt samples and random urine samples of children and pregnant women were collected to detect salt iodine and urinary iodine levels.

In 2022, the median thyroid volume of children aged 8 - 10 in iodine deficient areas and iodine adequate areas of Inner Mongolia was 2.44 ml, and the goiter rate was 1.89% (123/6 496). There were statistically significant differences in thyroid volume and goiter rate between different league cities (H = 1 229.05, χ² = 34.13, P < 0.001). The coverage rate of iodized salt in 12 league cities was 98.51% (30 628/31 090), the consumption rate of qualified iodized salt was 94.42% (29 355/31 090), and the median salt iodine was 22.80 mg/kg. The median urinary iodine of children (n = 20 968) was 195.00 μg/L, among which the median urinary iodine in 7 league cities was at the appropriate level of iodine nutrition (100 - 199 μg/L), and the median urinary iodine in 5 league cities was at the level of iodine nutrition exceeding the appropriate level (200 - 299 μg/L). The median urinary iodine of pregnant women (n = 10 122) was 168.00 μg/L, among which, except for Bayannur (149.18 μg/L), the median urinary iodine in other 11 league cities was at the appropriate level of iodine nutrition (150 - 249 μg/L).

The overall iodine nutrition of children and pregnant women in Inner Mongolia is at an appropriate level, but some pregnant women still face the risk of iodine deficiency. In the future, the focus of iodine deficiency disorders prevention and control should be on iodine nutrition monitoring for special needs populations.

Iodine; Urine; Edible salt; Thyroid