Iodine nutritional status of pregnant women in rural areas of Shijiazhuang City after 17 years of salt iodization / 中华地方病学杂志

ABSTRACT

Objective To explore the iodine status of pregnant women after 17 years of salt iodization in rural areas of Shijiazhuang City.Methods Probability proportionate to size sampling was employed in which 30 towns were selected from the 211 towns in the rural areas of Shijiazhuang City.In each town selected,40 pregnant women were randomly selected to collect their spot urine samples,edible salt samples and drinking water samples from their households to measure iodine content.The iodine content of salt was determined quantitatively using a titration method (GB/F 13025.7-2012).The urinary iodine content was determined using the method of ammonium persulfate digestion arsenic cerium catalytic spectrophotometry (WS/T 107-2006).The iodine content in drinking water was determined by the method of standard test for drinking water.Results A total of 1 200 salt samples was collected from the pregnant women's households in 30 towns,with the overall median iodine content being 27.2 mg/kg.The median salt iodine content in 30 towns varied from 23.4 to 32.6 mg/kg.A total of 478 water samples were collected,with a median of 5.3 μg/L.The median urinary iodine content (UIC) of 1 200 pregnant women in 30 towns was 146.4 μg/L.The median UIC in the first (≤ 13 weeks),second (14 ～ 26 weeks) and third (≥27 weeks) trimesters was 166.3,145.1 and 133.5 μg/L,respectively.The median UIC in the first trimester was significantly higher than that in the third trimester (Mann-Whitney Test,U =18 265,P ＜ 0.05).Except for the 9-20 and 37-40 weeks period of pregnancy,the median UIC was lower than the WHO criteria (150 μg/L).Tested by linear correlation,the pregnant women's median UIC did not correlate with median salt iodine (r =0.725,P ＞ 0.05).Conclusion Under the current universal salt iodization,the pregnant women's iodine intake could almost meet their requirement in the rural areas of Shijiazhuang City,however,mild iodine deficiency has existed in the third trimester.Alternative measures of iodine supplement could be implemented.