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.

Role of medical resource level in iodine deficiency disorder

Background:Iodine deficiency disorders(IDDs)refer to a series of diseases caused by the human body's insufficient iodine intake.Edible salt became iodized in China in 1996,which yielded remarkable results.We have known that IDDs is associated with iodine in the human body,but it is not clear whether IDDs is related to medical resource level.Methods:We collected the number of IDDs cases and an index for the level of medical resource from 31 provinces,autonomous regions and municipalities directly under the central government in China.All data came from the China Statistical Yearbook of Health and Family Planning issued in 2013 by the Peking Union Medical College Publishing House.Data standardization and linear regression analysis were used.Results:The results showed that IDDs correlated with the number of beds in medical and health institutions,number of medical health personnel,number of medical and health institutions,total health expenditure,average health expenditure per capita,medical insurance for urban resident and new rural cooperative medical rural residents(P<0.01).In a multiple linear regression,IDDs was most significantly associated with the number of beds in hospitals,the number of rural health personnel,the number of basic medical and health institutions and government health expenditure for these institutions. Conclusion:Based on the experimental data,we concluded that IDDs had a positive connection with the medical resource level,and basic and rural areas had a more significant association with IDDs.This analysis provides new and explicit ideas for iodine prevention and control work in China.

Iodine deficiency disorders in Gansu Province in 2014

Objective To master the situation of iodine deficiency disorders(IDD)and the people’s iodine nutritional status after implementation of the new salt iodine standard in Gansu Province in 2012.Methods Totally 30 counties(cities)were selected in Gansu Province by population proportionate to size sampling(PPS)method in 2014,and one primary school was selected in

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.

Association of iodized salt with goiter prevalence in Chinese populations: a continuity analysis over time

Background: Iodine deficiency disorders(IDD) refer to diseases that are caused by insufficient iodine intake, and the best strategy to prevent IDD is the addition of iodine to dietary salt. Because iodine deficiency is a common cause of goiter, the prevalence as effectively controlled after the implementation of universal salt iodization(USI) in China. However, there is substantial controversy as to whether the incidence of thyroid disorders is related to iodized salt intake. Therefore, we aimed to clarify whether the risk of goiter can be promoted by USI.Methods: A longitudinal continuous study based on the national monitoring results of IDD in China was performed for 3 consecutive years. We recorded the following indicators of IDD from 31 provinces: goiter number, two degrees of goiter(the degree of goiter severity) and cretinism(three endemic diseases), iodized salt intake, median urinary iodine concentration(UIC), soil iodine content and coverage rates of iodized salt. One-way Analysis of Variance(ANOVA) and linear regression analyses examined the differences between the three groups and correlations, respectively. Data were collected from the Chinese national IDD surveillance data in 2011-2013, and the background values of Chinese soil elements were published in 1990.Results: A reference male's daily intake of maximum iodine was 378.9μg, 379.2μg and 366.9μg in 2011, 2012, and 2013, respectively. No statistical association between daily iodized salt intake and the three endemic diseases was observed in 2011-2013(P >0.05). No association was observed between daily iodized salt intake and the UIC of children in 2011(P>0.05). Linear regression revealed no significant correlation between the soil iodine content and three endemic diseases. The present study indicated no difference in the daily iodized salt intake in each province during three years(F=0.886, P=0.647). The coverage rate of iodized salt remained above 98.7%, and goiter rates were stable in 2011-2013.Conclusion: There was no significant association between iodized salt intake and the three endemic diseases, suggesting that the current nutrition level of iodized salt did not cause the high goiter prevalence.