Relationship between Iodine Content in Household Iodized Salt and Thyroid Volume Distribution in Children

Objective To assess the effect of different levels of salt iodine content on thyroid volume（ThV） distribution using data from the 1999, 2011, and 2014 Chinese national iodine deficiency disorder（IDD） surveys. Methods Probability proportion to size（PPS） sampling method was used to obtain a representative national sample of 34,547, 38,932, and 47,188 Chinese children aged 8-10 years in 1999, 2011, and 2014 Chinese national IDD surveys, respectively. The iodine content in household iodized salt and urinary iodine concentration were measured and thyroid ultrasound examination was performed. The data were analyzed by SAS software using histograms and box plots. The skewness and kurtosis were calculated for testing the normality of ThV. Results The median iodine content in household iodized salt dropped from 42.30 mg/kg in 1999 to 25.00 mg/kg in 2014. The median urinary iodine concentration of children aged 8-10 years decreased from 306.0 μg/L in 1999 to 197.9 μg/L in 2014. The median and interquartile range（IQR） of ThV in 1999, 2011, and 2014 surveys were 3.44 m L and 1.50 m L, 2.60 m L and 1.37 m L, 2.63 m L and 1.25 m L, respectively. The skewness and kurtosis of ThV distribution in 1999, 2011, and 2014 surveys were 1.34 and 5.84, 0.98 and 3.54, 1.27 and 5.49, respectively. Conclusion With reduced salt iodization levels, the median urinary iodine concentration and median ThV of children decreased significantly, and the symmetry of the ThV distribution improved.

Control of Iodine Deficiency Disorders Following 10-Year Universal Salt Iodization in Hebei Province of China

Objective To evaluate the effectiveness of universal salt iodization （USI） for the control of IDD in Hebei province since it was implemented in 1995, identify the problems currently encountered in the implementation of USI and provide practical proposals for addressing these problems. Methods Probability proportionate to size sampling （PPS） was employed in the surveillance of IDD, for which a total of 1200 school children aged 8-10 years were randomly selected from 30 counties around the whole province during each IDD survey. The iodine content of salt was determined quantitatively with the titration method. The iodine content of urinary samples was measured by the method of ammonium persulfate oxidation. Results The coverage of iodized salt increased from 65.0% in 1995 to 98.0% in 1999, then decreased to 88.1% in 2005 which was below the national standard of 90%. The median urinary iodine of children aged 8-10 years varied between 160.1 μg/L and 307.4 μg/L, which was above the national standard. The proportion of urinary samples with iodine content above 300 lag/L was over 30% in 2005, implying exorbitant iodine nutrition among the children. The goiter rate （TGR） among children aged 8-10 years dropped from 11.8% in 1995 to 2.7% in 2005, indicating that the spread of endemic goiter was under control. Conclusion Preliminary elimination of IDD was achieved by USI in Hebei province. Nevertheless, some problems still existed in USI such as non-iodized salt competition, over iodization and un-standardized iodization. In order to address these problems, the management and supervision of salt market needs to be strengthened to prevent non-iodized salt from reaching households; updating equipment and modifying techniques are also necessary to ensure the quality of iodized salt; to clarify the causes of excessive urinary iodine content, the various sources of iodine from the diet need to be investigated in the future.

Iodine Content of Processed Foods and Condiments Sampled in China, 2017-2019

Introduction: Facing the challenge of increasing consumption of processed foods in China, along with the demand for salt reduction, and dynamic adjustment of universal salt iodization (USI) policy, it is necessary to timely evaluate the distribution of iodine content in processed foods and condiments, so as to provide more accurate data for population dietary iodine intake assessment. Methods: From markets in 6 cities and e-commerce platforms, cereal, tuber, legume, meat, fish, egg, and dairy products, and condiments, consumed by volunteers who attended in iodine intake investigation, and top selling products in particular with well-noted brands were preferentially sampled during 2017 to 2019. After being mixed and homogenized, each sample was detected by ICP-MS method. The range and medium of iodine content in each type of product were given. Results: After merging samples with close value in the same style of the same brand, and screening out samples with no added salt or low sodium content (≤120 mg/100g), total 725 data were sub-grouped and analyzed. In comparison with the 95th percentile of the iodine distribution in relative nature source, assessed by our previous study, nearly 77% of products made from grains, potatoes, beans, nuts, livestock and poultry meat were presumed to be processed with iodized salt. In somewhat, related with sodium value marked on food labeling, the median iodine ranged from 1.1 mg/100g to 149 mg/100g. The variation of iodine in egg, milk and fish made products, and seaweed or with seaweed products was greatly affected by the background of ingredients, the median content most floated between 12.8 mg/100g and 86.8 mg/100g, even up to 1800 mg/100g in seasoned seaweed. Based on the frequency of iodine digital and the ratio of iodine to sodium, it was speculated that nearly 90% of soy sauce and 73.5% of other seasonings like vinegar, sauce, paste, etc., were not added iodized salt, with overall median iodine 4.0 mg/100g and 12 mg/100g respectively. Conclusion: Using iodized salt in processed foods is an approach of USI police. Affected by the nature backgrounds of ingredients composed, the amount of salt used, and the regulated fortification level, iodine content in each kind of product varied largely. It’s important to establish a monitoring system in processed foods, as well as fortification salt, to control the benefit and risk of iodine health.

Effect of universal salt iodization on antithyroid drugs

Iodine deficiency disease （IDD） is common in China. An universal salt iodization （USl） program has been implemented by the Chinese government since 1996. As a result, the goiter rate in 8- to 10-year old children decreased from 20.4% in 1995 to 5.8% in 2002.1 But the adverse effects of iodine excess such as iodine-induced hyperthyroidism, iodine-induced goiters, iodine-induced hypothyroidism, etc. have become a great concern to healthcare professionals as well as the general population. The impact of USI on antithyroid drugs （ATDs） might become a potential challenge to address. With a special grant from the Department of Disease Control, the Health Ministry of China, we conducted a prospective study on the effects of USI on ATDs at the thyroid section of the Endocrinology Clinic of Peking Union Medical College Hospital （PUMCH）, Beijing.