Comparison of Thyroglobulin and Thyroid Function in Pregnant Women between Counties with a Median Urinary Iodine Concentration of 100-149 μg/L and 150-249 μg/L

Objective This study explored whether thyroglobulin and thyroid disease prevalence rates were higher in pregnant Chinese women with a median urinary iodine concentration of 100-149μg/L,compared with those with a median urinary iodine concentration of 150-249μg/L maintained through sustainable universal salt iodization.Methods This was a cross-sectional study in which 812 healthy pregnant women were enrolled to collect samples of their household edible salt,urine,and blood during their routine antenatal care in the18 counties in Fujian Province,China.The levels of salt iodine concentration,urinary iodine concentration(UIC),free triiodothyronine(FT3),free thyroid hormone(FT4),thyroid-stimulating hormone(TSH),thyroglobulin(Tg),thyroid peroxidase antibody and thyroglobulin antibody were assessed during the routine antenatal care visits.Results The median UIC(m UIC)in pregnant women was 130.8μg/L(interquartile range=91.5-198.1μg/L)in the counties with an m UIC of 100-149μg/L(Group I),and 172.0μg/L(interquartile range=123.5-244.4μg/L)in the counties with an m UIC of 150-249μg/L(Group II).Goiter prevalence and thyroid nodule detection rates showed no difference between Group I and Group II(P>0.05).Except for FT4 values,the TSH,FT4,FT3,Tg and Tg values>40(μg/L)and the thyroid diseases prevalence rate(TDR)showed no significant differences between Group I and Group II(P>0.05),whether or not iodine supplementation measures were taken.Conclusion Compared with an m UIC of 150-249μg/L,not only there was no difference in thyroid morphology,but also the Tg value,rate of Tg values>40μg/L,and TDR were not higher in pregnant women in the counties with an m UIC of 100-149μg/L achieved through sustainable universal salt iodization in Fujian Province,China.

Iodine Nutrition, Thyroid-stimulating Hormone, and Related Factors of Postpartum Women from three Different Areas in China: A Cross-sectional Survey

Objective Studies on the relationship between iodine,vitamin A(VA),and vitamin D(VD)and thyroid function are limited.This study aimed to analyze iodine and thyroid-stimulating hormone(TSH)status and their possible relationships with VA,VD,and other factors in postpartum women.Methods A total of 1,311 mothers(896 lactating and 415 non-lactating)from Hebei,Zhejiang,and Guangxi provinces were included in this study.The urinary iodine concentration(UIC),TSH,VA,and VD were measured.Results The median UIC of total and lactating participants were 142.00µg/L and 139.95µg/L,respectively.The median TSH,VA,and VD levels in all the participants were 1.89 mIU/L,0.44μg/mL,and 24.04 ng/mL,respectively.No differences in the UIC were found between lactating and non-lactating mothers.UIC and TSH levels were significantly different among the three provinces.The rural UIC was higher than the urban UIC.Obese mothers had a higher UIC and a higher prevalence of excessive TSH.Higher UICs and TSHs levels were observed in both the VD deficiency and insufficiency groups than in the VD-sufficient group.After adjustment,no linear correlation was observed between UIC and VA/VD.No interaction was found between vitamins A/D and UIC on TSH levels.Conclusion The mothers in the present study had no iodine deficiency.Region,area type,BMI,and VD may be related to the iodine status or TSH levels.

Effect of Reduction in Iodine Content of Edible Salt on the Iodine Status of the Chinese Population

Objective The aim of this study was to evaluate the impact of the revised Chinese National Standard GB26878-2011 ＇Iodine Content in Edible Salt＇ on the iodine status among the Chinese population. Methods In 2011 and 2014, the probability proportionate to size sampling（PPS） was used in each Chinese province to obtain the representative data. In each sampling unit, school children aged 8-10 years and pregnant women were selected. Key indicators included urinary iodine concentration（UIC）, thyroid volume（TV）, and the iodine content in edible household salt. Results The median urinary iodine concentration（MUIC） decreased between 2011 and 2014 from 238.6 to 197.9 μg/L in school-age children. The number of provinces with iodine excess decreased to zero. The proportion of children whose UIC was 〉 300 μg/L was 18.8% and decreased to 11% compared with 29.8% in 2011. There was no significant difference in UIC 〈 50 μg/L between 2014（4.3%） and 2011（3.7%）（P 〉 0.05）. The MUIC among pregnant women in 2014 was more concentrated between 110 and 230 μg/L. The goiter rate among children aged 8-10 years was unchanged, both the goiter rate of 2011 and 2014 remaining below 5%, in view of the sustainable elimination of iodine deficiency disorders. Conclusion The National Standard GB26878-2011 ＇Iodine Content in Edible Salt＇ that was introduced in March 2012 resulted in an overall improvement in iodine status, reducing the risk of excessive iodine intake in the Chinese population.