Serum Thyroglobulin——A Sensitive Biomarker of Iodine Nutrition Status and Affected by Thyroid Abnormalities and Disease in Adult Populations

Objective To evaluate the usefulness of the thyroglobulin （Tg） level in adults as a nutritiona biomarker of iodine status and to identify the factors related to the serum Tg level. Methods A cross-sectional study was conducted in adult populations of areas differing in iodine nutrition from three provinces （Autonomous Region） in China. Serum levels of thyroid hormones and Tg as well as thyroid autoantibodies were measured. The thyroid volume and nodule were measured by ultrasound. A multivariate linear regression analysis was used to assess iodine intake and other indeterminate factors associated with the serum Tg level. Results A total of 573 adults were recruited for this study. The serum Tg levels differed significantly among the three groups （22.27 ~g/L, 9.73 pg/L and 15.77 pg/L in the excess, more-than-adequate, and deficient groups, respectively）. The results of multivariate linear regression analysis indicate that excess and deficient iodine intake, goiter, thyroid nodule, hypothyroidism are significantly related with higher Tg level, and TgAb positivity is significantly related with lower serum Tg. Conclusion The serum Tg level reflects abnormal thyroid function and is a sensitive functiona biomarker of iodine nutrition status.

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.

Time Series and Spatial Epidemiological Analysis of the Prevalence of Iodine Deficiency Disorders in China

Objective To recognize the spatial and temporal characteristics of iodine deficiency disorders(IDD),China national IDD surveillance data for the years of 1995–2018 were analyzed.Methods Time series analysis was used to describe and predict the IDD related indicators,and spatial analysis was used to analyze the spatial distribution of salt iodine levels.Results In China,the median urinary iodine concentration increased in 1995–1997,then decreased to adequate levels,and are expected to remain appropriate in 2019–2022.The goiter rate continually decreased and is expected to be maintained at a low level.Since 2002,the coverage rates of iodized salt and the consumption rates of qualified iodized salt(the percentage of qualified iodized salt in all tested salt) increased and began to decline in 2012;they are expected to continue to decrease.Spatial epidemiological analysis indicated a positive spatial correlation in 2016–2018 and revealed feature regarding the spatial distribution of salt related indicators in coastal areas and areas near iodine-excess areas.Conclusions Iodine nutrition in China showed gradual improvements.However,a recent decline has been observed in some areas following changes in the iodized salt supply in China.In the future,more regulations regarding salt management should be issued to strengthen IDD control and prevention measures,and avoid the recurrence of IDD.