Investigation on the status of neonatal heel blood thyroid stimulating hormone and iodine nutrition of pregnant women and children in Guizhou Province

Objective To understand the thyroid stimulating hormone (TSH) level of neonates and iodine nutritional status of pregnant women and children in Guizhou Province. Methods From 2016 to 2017, a city (district, county) in government location in Guizhou Province was selected as the urban survey site, and a county (city, district) whose economy was relatively backward and farther from the city (prefecture) in government location was selected as the rural survey site. In each survey site, 300 salt samples were collected for determination of salt iodine; 300 blood samples in the heel of neonates after birth 72 hours were taken for measurement of TSH. The World Health Organization, United Nations International Children's Emergency Fund, and the International Committee for the Control of Iodine Deficiency (WHO/UNICEF/ICCIDD) recommend that when the proportion of neonates(TSH levels > 5 mU/L) is < 3%, the area is non-iodine-deficient. In other words, the 97th percentile (P97) value should be ≤5 mU/L. The normal reference value of the kit is ≤9 mU/L. And urinary iodine of 150 children aged 8 - 10 and 150 pregnant women was determined. Results A total of 5 400 edible salt samples were tested, the median of salt iodine was 27.9 mg/kg, and the consumption rate of qualified iodized salt was 94.89% (5 124/5 400); 5 400 neonatal heel blood samples were collected, the median of TSH was 2.62 mU/L, TSH P97 was 6.91 mU/L, and samples proportion with TSH > 5 mU/L was 10.67% (576/5 400), and > 9 mU/L (the cut-off value of kit) was 1.00% (54/5 400). Among 3 588 cases of children aged 8 to 10 years, the median of urinary iodine was 212.3 μg/L, those with urinary iodine < 50 μg/L was 2.81% (101/3 588), and < 100 μg/L was 12.76% (458/3 588). Among the 2 695 pregnant women, the median of urinary iodine was 163.1 μg/L, and 44.04% (1 187/2 695) were < 150 μg/L. Conclusions The quality of iodized salt is stable in Guizhou, the iodine nutrition status of children and pregnant women are good. The neonatal TSH and nutritional status of pregnant women should be monitored in the future. Key words: Thyroid stimulating hormone; Iodine; Neonate; Children; Pregnant women