Iodine nutrition and thyroid function in different populations after 20 years of universal salt iodization in iodine deficiency area of Shanxi Province / 中华地方病学杂志

Objective To understand the iodine nutritional status and thyroid function of different populations after 20 years of universal salt iodization in iodine deficiency area of Shanxi Province, and to provide data support for scientific iodine supplementation according to local conditions. Methods In 2014, six townships (Chengguan, Dadeng, Dengzhuang, Gucheng, Xiangling and Fencheng townships) in Xiangfen County, Linfen City, Shanxi Province, were selected as the place of investigation. Four hundred school-age children aged 6 - 12 years (school-age children), 400 child-bearing women aged 18 - 44 (child-bearing women), 400 pregnant women, 400 lactating women and their 0 - 6 months breast-feeding infants (breast-feeding infants), and 400 children aged 7 -24 months were selected by two-stage sampling method. Water samples of school-age children's domestic drinking water and salt samples for domestic consumption were collected, and the water iodine and salt iodine were detected by arsenic and cerium catalytic spectrophotometry ( recommended by the National Iodine Deficiency Disorders Reference Laboratory) and "General Test Method in Salt Industry-Determination of Iodine" (GB/T 13025.7-2012). Random urine samples of all subjects were collected, urine iodine was detected by "Method for Determination of Iodine in Urine by As3+-Ce4+ Catalytic Spectrophotometry" ( WS/T 107-2006 ) . Samples of filter paper dried blood spots (DBS) of school-age children, child-bearing women, pregnant women, lactating women and breast-feeding infants were collected, and serum total thyroxine (TT4) and thyroid stimulating hormone (TSH) levels were detected by time-resolved fluorescence immunoassay. Results A total of 290 water samples were collected, and the median of water iodine was 9.37μg/L. A total of 406 salt samples were collected, the median of salt iodine was 25.0 mg/kg, the coverage rate of iodized salt was 98.52％ (400/406), and the consumption rate of qualified iodized salt was 92.61％ (376/406). Urine samples of 389 school-age children, 379 child-bearing women, 363 pregnant women, 365 lactating women, 366 breast-feeding infants, and 366 children aged 7 - 24 months were collected, and the medians of urine iodine were 200.7, 175.0, 186.0, 113.2, 285.8 and 204.8 μg/L, respectively. Among them, school-age children, breast-feeding infants, and children aged 7-24 months were over the appropriate level, while the rest populations were at the iodine appropriate levels. Blood samples of 402 school-age children, 397 child-bearing women, 398 pregnant women, 390 lactating women, and 386 breast-feeding infants were collected, and the medians of TT4 were 127.2, 110.2, 141.7, 95.8 and 139.0 nmol/L, respectively; the medians of TSH were 1.2, 0.9, 0.8, 0.9 and 0.9 mU/L, respectively, and they were all within the reference ranges. The abnormal rates of TT4 (8.46％, 33/390) and TSH (7.95％, 31/390) in lactating women were higher than those in school-age children, child-bearing women, pregnant women and breast-feeding infants [TT4 abnormal rates were 0.25％(1/402), 1.26％ (5/397), 0.50％ (2/398), 1.04％ (4/386), respectively; TSH abnormal rates were 1.24％ (5/402), 1.51％ (6/397), 1.51％ (6/398) and 0.78％ (3/386), respectively, P < 0.05]. The rate of thyroid dysfunction in lactating women (7.95％, 31/390) was higher than those in the rest populations [1.24％ (5/402), 1.51％ (6/397), 1.51％ (6/398), 0.78％ (3/386), P < 0.05]. Conclusions The iodine intake of different populations in the survey area is generally sufficient, and the current salt iodine content standard can meet the iodine nutrition needs of different populations. Lactating women have a high rate of thyroid dysfunction. It is suggested to stick to the strategy of universal salt iodization to prevent iodine deficiency hazards in iodine deficiency areas, and further strengthen the monitoring of iodine nutrition and thyroid function of pregnant women and lactating women.

Relationship between Iodine Content in Household Iodized Salt and Thyroid Volume Distribution in Children / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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 mL and 1.50 mL, 2.60 mL and 1.37 mL, 2.63 mL and 1.25 mL, 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.</p><p><b>CONCLUSION</b>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.</p>

Iodine Status after a 3-Year Universal Salt Iodisation in Sarawak, Malaysia

Following the reveal of borderline iodine sufficiency among the Sarawakians from the 2008 National Iodine Deficiency Disorders (IDDs) survey, a mandatory universal salt iodization (USI) was implemented in Sarawak thereafter. This study aimed to determine the current status of USI in Sarawak after a 3-year implementation of USI from 2008 to 2011. The IDD survey was conducted between Jun 2011 to July 2011 involving six districts in Sarawak (Sarikei, Mukah, Kapit, Sibu, Bintulu and Miri). The schools were selected via multistage proportionate-to-population size sampling technique and the children were randomly selected via systematic sampling. A total of 19 schools and 661 children were recruited into the survey. Thyroid size was determined by palpation and was and graded according to the classification of the World Health Organization (grade 0-2). The iodine excretion level in spot morning urine was measured using in-house microplate method. The urinary iodine concentration (UIC) values were compared by Kruskal-Wallis test and Chi-square tests were used to compare categorical variables. A total of 610 school children were participated in the study (92.3%). The TGR of grade 1 and 2 was found to be 0.3% (n = 2). Overall the median UIC level was 154.2 (IQR, 92.7 - 229.8) µg/L, with the highest median UIC been observed in Sarikei [178.0 (IQR, 117.6 - 308.9) µg/L], followed by Mukah [174.8 (IQR, 99.0 - 224.3) µg/L)], Miri [158.6 (IQR, 92.3 - 235.4) µg/L], Sibu [147.0 (IQR, 89.8 - 221.4) µg/L], Bintulu [142.3 (IQR, 52.8 - 245.1) µg/L] and Kapit [131.0 (IQR, 88.6 - 201.9) µg/L]. One in every ten child was of iodine deficient (UIC < 50µg/L) while a third of the child (32%) were of adequate level of UIC. The present findings indicate that the mandatory USI successfully improves the iodine level of children in Sarawak. However, regular and proper monitoring of the UIC level in the communities is needed to prevent excessive iodine intake.​

Effects of Increased Iodine Intake on Thyroid Disorders

Iodine is a micronutrient essential for the production of thyroid hormones. Iodine deficiency is the most common cause of preventable mental impairment worldwide. Universal salt iodization (USI) has been introduced in many countries as a cost-effective and sustainable way to eliminate iodine deficiency disorders for more than 25 years. Currently, the relationship between USI and iodine excess has attracted more attention. Iodine excess can lead to hypothyroidism and autoimmune thyroiditis, especially for susceptible populations with recurring thyroid disease, the elderly, fetuses, and neonates. Nationwide USI was introduced in China in 1996. This review focused on the effects of iodine excess worldwide and particularly in China.

Iodized Salt Consumption in Sudan: Present Status and Future Directions.

Iodine Deficiency Disorders (IDD) Control Programme in Sudan adopted salt iodization as the long-term strategy in 1994. In 2000, it was found that less than 1% of households were using adequately-iodized salt. The objectives of this study were to: (i) study the coverage and variation of different geographical regions of Sudan regarding access to and use of iodized salt, (ii) explore the possible factors which influence the use of iodized salt, (iii) develop recommendations to help in the implementation of the Universal Salt Iodization (USI) strategy in Sudan. This paper is based on the Sudan Household Health Survey (SHHS) dataset. A total sample of 24,507 households was surveyed, and 18,786 cooking salt samples were tested for iodine levels with rapid salt-testing kits. Nationally, the percentage of households using adequately-iodized salt increased from less than 1% in 2000 to 14.4%, with wide variations between states. Access to iodized salt ranged from 96.9% in Central Equatoria to 0.4% in Gezira state. Population coverage with iodized salt in Sudan remains very low. The awareness and political support for USI programme is very weak. National legislation banning the sale of non-iodized salt does not exist. Utilization of the already-existing laws, like the National Standardization and Metrology Law (2008), to develop a compulsory national salt specification, will accelerate the USI in Sudan.

Iodine nutritional status in adolescents after a decade of salt iodization in three cities of Guangdong / 中华内分泌代谢杂志

A cross-sectional survey of 3589 adolescents was conducted in three cities from different typical geographical zones of Guangdong province. The median urinary iodine concentrations (MUI) of adolescents in Nanxiong, Guangzhou and Maoming were 286.6,204.1 and 166.0μ/L, respectively. The MUI of all these adolescents Was 231.7μg/L, which was slightly higher than the current World Health Organization recommendation.

Analysis of detection rate of thyroid malignant tumor before and after universal salt iodization and histological types / 吉林大学学报(医学版)

Objective To investigate and evaluate the detection and the variety of histology type constituent of the thyroid malignant tumor before and after universal salt iodization.Methods 1011 clinical pathological data of thyroid malignant tumor confirmed pathologically from 1961 to 2000 was retrospectively analyzed.The detection rate of thyroid malignant tumor,the constituent ratios of each histology type and the changes of age and sex distribution in main types of thyroid malignant tumor were determined.Results The total detection rate of thyroid malignant tumor after universal salt iodization (USI) (0.69%) were obviously increased compared with before universal salt iodization(0.46%,P40 years old) than before USI(≤40 years old).The incidence rates of thyroid malignant tumor in female patients were higher than male patients before and after USI.Conclusion The proportion and average age of thyroid malignant tumor increases after USI.The histological types of thyroid carcinoma have changes after USI:the proportion of PC increases obviously,the proportion of FC decreases accordingly.The average age of thyroid malignant tumor sufferers tends to increase and the peak ages of PC,FC and UC raise after USI.

A comparative epidemiologic survey of hyperthyroidism in areas with different iodine intake / 中华内分泌代谢杂志

Objective To investigate the epidemiology of hyperthyroidism in three rural communities with different iodine intake after universal salt iodization (USI) since 1996 as well as the influence of USI on the incidence of hyperthyroidism. Methods Inhabitants in Panshan community did not take iodized salt whereas inhabitants in Zhangwu and Huanghua communities have taken iodized salt since 1996. The thyroid function, thyroid autoantibodies, urinary iodine concentration and thyroid B ultrasound were performed in 1103, 1584 and 1074 subjects respectively in the three communities and the number of hyperthyroidism patients between 1991 and 1999 was collected to calculate the yearly average incidence of hyperthyroidism. Results The median urinary iodine concentrations in Panshan, Zhangwu and Huanghua were 103 ?g/L, 375 ?g/L and 615 ?g/L, respectively (P0.05) andtheprevalenceofsubclinicalhyperthyroidism was 3.7%, 3.9% and 1.1%, respectively. Comparing the yearly average incidence of hyperthyroidism of 1996～1999 with that of 1991～1995, a significant increased incidence in Panshan, while a slight but insignificant elevated one in Zhangwu and a fixed one in Huanghua were found. Conclusion USI can not result in a raise of the prevalence of active hyperthyroidism as well as subclinical hyperthyroidism. The increase of iodine intake is not the only explanation for the raising of the incidence of hyperthyroidism.

Retrospective study on thyroid diseases after universal salt iodization in mild iodine deficiency area / 中华内分泌代谢杂志

Objective To investigate the effect of universal salt iodization (USI) on the profile of in-patient thyroid diseases. Methods Informations on thyroid diseases were collected by retrospective approach in hospitalized patients. Results With USI for 1-4 years, the incidence of thyroid diseases in the total in-patient cases increased from 7.6‰ to 11.0‰, the female/male ratio increased from 3.6 to 4.1, patients aged