High Iodine Areas Research Articles

Analysis of Thyroid Autoantibodies and Thyroid Stimulating Hormone Expression in Patients with Thyroid Diseases in High Iodine Areas of Cangzhou

Objective: To analyze the differences in the expression of thyroid autoantibodies and thyroid-stimulating hormone in people with thyroid disease in the high iodine area of Cangzhou City. Methods A total of 90 patients with thyroid disease from high iodine area of Cangzhou City were enrolled, including 30 patients with hypothyroidism, 30 patients with goiter and 30 patients with thyroid cancer. A total of 30 healthy patients at the same time and in the same region were selected as the control. The subjects were divided into four groups: hypothyroidism group, Goiter group, Thyroid cancer group, and control group. The TSH levels and thyroid autoantibody levels of the four groups were analyzed. Results Compared with the control group, the levels of thyroid autoantibodies in the hypothyroidism, Goiter group and thyroid cancer group were significantly higher (P<0.05), and compared with the control group, the TSH levels in the hypothyroidism group and the thyroid cancer group were higher, and the TSH levels in the Goiter group were lower (P<0.05). Conclusion: Thyroid autoantibodies and thyroid-stimulating hormone are differentially expressed in different types of thyroid diseases in the high iodine area of Cangzhou City, which can be used as reference indicators for the identification and diagnosis of different types of thyroid diseases.

A Meta-Analysis of the Prevalence of Children Goiter in High Water Iodine Areas of China.

Although there are now a large number of studies confirming that high iodine levels can cause goiter, there is controversy and a lack of quantitative data. A systematic search of PubMed, Web of Science, China National Knowledge Infrastructure, Wanfang Database, and China Biomedical Database for literature on high iodine and goiter in children was performed with a time limit from January 2013 to October 2023. After screening the literature based on the inclusion criteria, extracting the literature data, and evaluating the risk of bias of the included studies, a single-arm meta-analysis was performed using R 4.0.4 software. Twenty-three studies with a total of 50,980 subjects were included. Meta-analysis showed that the prevalence of goiter among children in water-borne iodine-excess areas was 6.0% [95% CI (4.3%, 7.6%)], and subgroup analyses showed that the prevalence of goiter in children with water iodine 100.1-150 µg/L, 150.1-300 µg/L, and > 300 µg/L was 7.5% [95% CI (0.0%, 15.8%)], 5.5% [95% CI (3.1%, 8.0%)], and 10.2% [95% CI (6.7%, 13.6%)], respectively, and the difference was statistically significant (P < 0.01); The prevalence of goiter among children in the northern China (5.8% [95% CI (4.1%, 7.5%)]) was higher than that in the southern China (3.5% [95% CI (1.0%, 6.0%)]) (P < 0.01); the prevalence of goiter in children with urinary iodine levels 100-199 µg/L, 200-299 µg/L, and ≥ 300 µg/L was 2.4% [95% CI (1.9%, 2.9%)], 3.3% [95% CI (1.9%, 4.8%)], and 7.3% [95% CI (4.4%, 9.9%)], respectively, the difference was statistically significant (P < 0.01); the prevalence of goiter in children aged 8, 9, 10, 11, and 12 years old was 5.1% [95% CI (3.9%, 6.4%)], 8.0% [95% CI (4.0%, 11.9%)], 6.2% [95% CI (3.9%, 8.5%)], 5.5% [95% CI (0.0%, 13.2%)], and 5.4% [95% CI (0.0%, 15.1%)], and when age ≥ 9 years, the relationship between goiter prevalence and age showed a trend toward decreasing with age, but the relationship between different age was no statistical difference in the prevalence of goiter between ages. urinary iodine. The prevalence of goiter in children was higher in areas with high water iodine; the prevalence of goiter in children in the north was significantly higher than that in the south; the prevalence of goiter in children tends to increase with increased urinary iodine levels.

Association between different water iodine exposures and thyroid cancer: A retrospective study of high water iodine areas in China from 2009 to 2020

In recent years, the incidence of thyroid cancer has been on a significant rise worldwide, and a number of environmental factors have been suspected to be risk factors for thyroid cancer, especially the relationship between iodine intake and thyroid cancer has attracted attention. In this study, we want to assess the relationship between different water iodine exposures and thyroid cancer incidence before and after water alteration in areas with high water iodine in China. Thyroid cancer patients (2009–2020) were enrolled at two hospitals, both in Heze City, Shandong Province, an area with high water iodine levels. According to the criteria of the study, 5826 cases out of 8785 cases were selected for inclusion in the study. Before and after water alteration, the incidence of thyroid cancer was highest in areas with water iodine concentrations of 200–300 μg/L in high iodine areas. In areas where water iodine decreased to adequate iodine levels, there was a strong negative correlation between the decreased level of water iodine and the incidence of thyroid cancer. In addition, in cases with pathology reports, we found that the greater the decrease in water iodine values, the markedly smaller the maximum diameter of the thyroid cancer lesions. Taken together, these findings suggest that we should continue to monitor the incidence of thyroid cancer in areas with high water iodine and continue to optimize population iodine intake to reduce the incidence of thyroid cancer.

Prediction modeling of geogenic iodine contaminated groundwater throughout China

Geogenic iodine-contaminated groundwater represents a threat to public health in China. Identifying high-iodine areas is essential to guide the mitigation of this problem. Considering that traditional analytical techniques for iodine testing are generally time-consuming, laborious, and expensive, alternative methods are needed to supplement and enhance existing approaches. Therefore, we developed an artificial neural network (ANN) model and assessed its feasibility in terms of predicting high iodine levels in groundwater in China. A total of 22 indicators (including climate, topography, geology, and soil properties) and 3185 aggregated samples (measured groundwater iodine concentrations) were utilized to develop the ANN model. The results showed that the accuracy and area under the receiver operating characteristic curve of the model on the test dataset are 90.9% and 0.972, respectively, and climate and soil variables are the most effective predictors. Based on the prediction results, a high-resolution (1-km) nationwide prediction map of high-iodine groundwater was produced. The high-risk areas are mainly concentrated in the central provinces of Henan, Shaanxi, and Shanxi, the eastern provinces of Henan, Shandong, and Hebei, and the northeastern provinces of Liaoning, Jilin, and Heilongjiang. The total number of people estimated to potentially be at high-risk areas because they use untreated high-iodine groundwater as drinking water is approximately 30 million. Considering the growing demand for groundwater in China, this work can guide the prioritization of groundwater contamination mitigation efforts based on regional groundwater quality levels to enhance environmental management.

Stopping the supply of iodized salt alone is not enough to make iodine nutrition suitable for children in higher water iodine areas: A cross-sectional study in northern China

For the sake of children's health, iodized salt supply has been stopped in many areas with excessive iodine in the drinking water, but children's iodine nutrition status and thyroid function after terminating the iodized salt supply is unknown. Objective We assessed the iodine nutrition, thyroid function and influencing factors for thyroid abnormalities in children from areas with different concentrations of water iodine; the supply of iodized salt has been stopped in high water iodine areas. This study aimed to evaluate whether the strategy of stopping the supplies of iodized salt alone is enough to avoid thyroid dysfunction in all areas with excess water iodine while still meeting the iodine nutrition needs of children. A cross-sectional study was conducted in children from four areas with different drinking water iodine concentrations in Tianjin, China. The drinking water samplings and spot urine samples were collected to estimate the external and internal iodine exposure levels. The thyroid volume was measured, and blood samples were collected to assess thyroid function. Logistic regression analysis was used to analyze risk factors for thyroid abnormalities. A dietary survey was conducted to determine the sources of iodine nutrition among the areas with different iodine concentrations in the drinking water. In the area with a drinking water iodine concentration ≥300 μg/L, the median urinary iodine concentration (UIC) in children was 476.30 (332.20-639.30) μg/L, which was higher than that in other groups (all P < 0.05), and the prevalence of thyroid nodules and the thyroid goiter rate were higher than those in the <100 μg/L, 100-150 μg/L and 150-300 μg/L areas (all P < 0.01). Binary logistic regression analysis indicated that the risk of thyroid abnormalities was significantly increased in the UIC 200-299 μg/L group (OR: 4.534; 95% CI: 1.565, 13.135; bootstrapped 95% CI: 1.689, 21.206, P = 0.004) and in the UIC ≥ 300 μg/L group (OR: 6.962; 95% CI: 2.490, 19.460; bootstrapped 95% CI: 2.838, 32.570, P = 0.001) compared to the 100-199 μg/L group. The iodine contribution rates from water in areas with water iodine concentrations ≥300 μg/L are up to 63.04%. After termination of the iodized salt supply, the level of iodine nutrition of children in the area with drinking water iodine concentrations ≥300 μg/L is still excessive. The water source needs to be replaced in this area. In the area with a water iodine concentration of 150-300 μg/L, it is proposed that stopping the supply of iodized salt is sufficient to achieve the proper iodine nutrition status in children.

Prevalence of thyroid function in pregnant and lactating women in areas with different iodine levels of Shanxi province

Objective: To investigate the effects of high iodine intake on thyroid function in pregnant and lactating women. Methods: A cross sectional epidemiological study was conducted among 130 pregnant women and 220 lactating women aged 19-40 years in areas with high environment iodine level (>300 μg/L) or proper environment iodine level (50-100 μg/L) in Shanxi in 2014. The general information, urine samples and blood samples of the women surveyed and water samples were collected. The water and urine iodine levels were detected with arsenic and cerium catalysis spectrophotometric method, the blood TSH level was detected with electrochemiluminescence immunoassay, and thyroid stimulating hormone (FT(4)), antithyroid peroxidase autoantibody (TPOAb) and anti-thyroglobulin antibodies (TGAb) were detected with chemiluminescence immunoassay. Results: The median urine iodine levels of the four groups were 221.9, 282.5, 814.1 and 818.6 μg/L, respectively. The median serum FT(4) of lactating women in high iodine area and proper iodine area were 12.96 and 13.22 pmol/L, and the median serum TSH was 2.45 and 2.17 mIU/L, respectively. The median serum FT(4) of pregnant women in high iodine area and proper iodine area were 14.66 and 16.16 pmol/L, and the median serum TSH was 2.13 and 1.82 mIU/L, respectively. The serum FT(4) levels were lower and the abnormal rates of serum TSH were higher in lactating women than in pregnant women in both high iodine area and proper iodine area, the difference was statistically significant (FT(4): Z=-6.677, -4.041, P<0.01; TSH: Z=8.797, 8.910, P<0.01). In high iodine area, the abnormal rate of serum FT(4) in lactating women was higher than that in pregnant women, the difference was statistically significant (Z=7.338, P=0.007). The serum FT(4) level of lactating women in high iodine area was lower than that in proper iodine area, the difference was statistically significant (Z=-4.687, P=0.000). In high iodine area, the median serum FT(4) in early pregnancy, mid-pregnancy and late pregnancy was 16.26, 14.22 and 14.80 pmol/L, respectively, and the median serum TSH was 1.74, 1.91 and 2.38 mIU/L, respectively. In high iodine area, the serum FT(4) level in early pregnancy was higher than that in mid-pregnancy and late pregnancy, and the serum TSH level was lower than that in mid-pregnancy and late pregnancy, the difference was statistically significant (FT(4): Z=-2.174, -2.238, P<0.05; TSH: Z=-2.985, -1.978, P<0.05). There were no significant differences in the positive rates of serum thyroid autoantibodies among the four groups of women and women in different periods of pregnancy (P>0.05). The morbidity rates of subclinical hyperthyroidism in pregnant women and lactating women in high iodine area were obviously higher than those in proper iodine areas, the difference was statistically significant (χ(2)=5.363, 5.007, P<0.05). Conclusions: Excessive iodine intake might increase the risk of subclinical hypothyroidism in pregnant women and lactating women. It is suggested to strengthen the iodine nutrition and thyroid function monitoring in women, pregnant women and lactating women in areas with high environmental iodine.

Surveys in Areas of High Risk of Iodine Deficiency and Iodine Excess in China, 2012-2014: Current Status and Examination of the Relationship between Urinary Iodine Concentration and Goiter Prevalence in Children Aged 8–10 Years

ObjectiveWe aimed to evaluate goiter prevalence and iodine nutritional status in areas with high levels of water iodine; to monitor the prevalence of iodine deficiency disorders (IDD) in areas at high risk of IDD; and to compare the prevalence of goiter and urine iodine (UI) concentrations between children living in the two areas. MethodsBased on surveillance from 2012-2014, we analyzed the concentration of UI and prevalence of goiter in 8-10-year-old children from 12 high-risk IDD provinces, and from 8 provinces and municipalities with excessive water iodine. We calculated goiter prevalence for each UI level according to World Health Organization (WHO) standards and constructed predictive prevalence curves. ResultsThe goiter prevalence and median UI of children from areas with high water iodine were not optimal, being above the WHO standards (5% and 100-199 µg/L, respectively), whereas those in high-risk areas fell within the standard. UI and goiter prevalence exhibited a U-shaped relationship in high-risk endemic areas and a parabolic relationship in areas of iodine excess. ConclusionIodine surplus in high-iodine areas leads to high goiter prevalence and UI. However, in high-risk areas, UI was optimal and goiter prevalence met the national criteria for IDD elimination.

Iodine nutritional status in the adult population of Shandong Province (China) prior to salt reduction program.

Tremendous differences in iodine status and daily iodine intake persist across provinces of China. The objective of the present study was to evaluate the iodine status and dietary iodine intake of Shandong adults before the implementation of the salt reduction program and a new salt iodization standard. Data from a baseline survey of the Shandong and Ministry of Health Action on Salt Reduction and Hypertension project (2011) were analyzed. The iodine contents of 1949 24-h urine samples and 136 drinking water samples were assayed. Daily urinary iodine excretion and daily iodine intake were calculated, analyzed, stratified by different analytical variables and compared with Chinese Dietary Reference Values. The median urinary iodine concentration and median daily iodine intake of Shandong adults were 248.5μg/L and 368.2μg/day, respectively. The median iodine intake of different groups was between the estimated average requirements and the upper limit, except group in water iodine >300μg/L with median iodine intake of 1200.7μg/L. Salt intake and iodine levels in drinking water related to iodine intake significantly. Shandong adults had more than adequate iodine nutrition, and the dietary iodine intake of the population was generally appropriate and safe except residents in high water iodine areas. In the context of the implementation of a salt reduction program and a new salt iodization standard, the iodine status of high water iodine areas may remain in the recommended level, but in low water iodine areas, the risk of inadequate iodine intake may increase, needing monitoring of urine iodine excretion, dietary iodine intake and iodized salt consumption regularly.

Neonatal thyroid function born to mothers living with long-term excessive iodine intake from drinking water.

The effects of long-term excessive maternal iodine intake on neonatal thyroid function are less known. This study aimed to assess the effects of maternal excessive iodine intake from drinking water on thyroid functions of both mothers and their neonates. This observational study was performed in high iodine (HI) areas and adequate iodine (AI) intake areas, including 384 healthy pregnant women in late gestation (mean week 39·3 ± 1·6 weeks) and their newborns. Blood and urine samples were obtained from pregnant women, while cord blood samples were obtained from neonates. Urinary iodine concentration (UIC) and thyroid function were evaluated. The median maternal UIC was 1241 and 217 μg/l in HI and AI areas, respectively (P < 0·001). The concentrations of serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) in neonates in HI areas were 7·33 mIU/l (range 5·47, 11·06 mIU/l), 2·93 ± 0·59 and 15·03 ± 1·92 pmol/l, respectively, while that were 4·71 mIU/l (range 3·96, 6·04 mIU/l), 2·31 ± 0·28 and 16·50 ± 1·35 pmol/l in AI neonates (P < 0·05). Similar changes were also observed in neonates in HI areas when excluding the effect of maternal thyroid autoimmunity. Cord blood TSH concentration (r = 0·31, P = 0·001) and FT3 concentration (r = 0·43, P = 0·001) were positively correlated with maternal UIC. Cord blood FT4 concentration was negatively correlated with maternal UIC (r = -0·25, P = 0·001). Mothers living in HI areas (β = 0·296, 95% CI: 0·163, 0·255) and with subclinical hypothyroidism (β = 0·360, 95% CI: 0·034, 0·175) contributed to elevated cord blood TSH concentration in neonates, while male neonates were more likely to present with higher TSH concentration compared with female infants (β = -0·760, 95% CI: -0·119, -0·033). Excessive iodine intake during pregnancy was associated with an increased rate of hyperthyrotropinaemia in neonates and their mothers, especially in male neonates.

Impact of removing iodised salt on children's goitre status in areas with excessive iodine in drinking-water.

The impact of removing iodised salt on children's goitre status in a high-iodine area (HIA) remains unclear. The aim of the present study was to explore the changes in the prevalence of goitre in children after removing iodised salt from their diet. For this purpose, three towns with the median water iodine content of 150-300 μg/l were selected randomly in Hengshui City, Hebei Province, China. A total of 452 and 459 children were randomly selected from the three towns in order to measure thyroid volume by ultrasound before and after removing iodised salt, respectively. Their goitre status was judged using the criteria of age-specific thyroid volume recommended by the WHO. After removing iodised salt, the overall median urinary iodine content (MUIC) of children decreased from 518 (interquartile range (IQR) 347-735) to 416 (IQR 274-609) μg/l. The MUIC of children across sex and age group decreased significantly except for the age group of 9 years. The overall prevalence of goitre in the three towns significantly decreased from 24·56% (n 111/452) to 5·88% (n 27/459) (P< 0·001). Goitre prevalence in children aged 8-10 years decreased from 33·70% (n 31/92), 23·32% (n 45/193) and 20·96% (n 35/167) to 6·10% (n 10/164), 5·52% (n 9/163) and 6·06% (n 8/132), respectively. Goitre prevalence in boys and girls decreased from 27·05% (n 66/244) and 21·63% (n 45/208) to 6·66% (n 15/226) and 5·15% (n 12/233), respectively. The decreases in the prevalence of goitre in children across sex and age group were all statistically significant. The present study revealed that goitre prevalence in children decreased significantly after removing iodised salt from their diet for about 1·5 years in the HIA in Hebei Province.

Impact of removing iodized salt on the iodine nutrition of children living in areas with variable iodine content in drinking water

Excess iodine in drinking water has emerged as a public health issue in China. This study assesses the effectiveness of removing iodized salt on reducing the iodine excess in populations living in high-iodine areas and also to identify the threshold value for safe levels of iodine in water. Twelve villages from 5 cities of Hebei Province with iodine content in drinking water ranging from 39 to 313µg/l were selected to compare the urinary iodine content of children aged 8-10years before and after removing iodized salt from their diet. For 3 villages where median water iodine content (MWIC) was below 110µg/l, following the removal of iodized salt (the intervention), the median urinary iodine content (MUIC) reduced to under 300µg/l decreasing from 365, 380, 351 to 247, 240, 281µg/l, respectively. However, the MUIC in the 9 villages with MWIC above 110µg/l remained higher than 300µg/l. The children's MUIC correlated positively with the MWIC in the 12 villages (p≤ 0.001). The linear regression equation after removing iodized salt was MUIC=0.6761MWIC+225.67, indicating that to keep the MUIC below 300µg/l (the iodine excess threshold recommended by the WHO) requires the MWIC to be under 110µg/l. Removing iodized salt could only correct the iodine excess in the population living in the areas with MWIC below 110µg/l. In the areas with water iodine above 110µg/l, interventions should be focused on seeking water with lower iodine content. This study suggests a threshold value of 110µg/l of iodine in drinking water to maintain a safe level of dietary iodine.

The Standard, Intervention Measures and Health Risk for High Water Iodine Areas

Our study aims to clarify the population nutrient status in locations with different levels of iodine in the water in China; to choose effective measurements of water improvement(finding other drinking water source of iodine not excess) or non-iodised salt supply or combinations thereof; to classify the areas of elevated water iodine levels and the areas with endemic goiter; and to evaluate the risk factors of water iodine excess on pregnant women, lactating women and the overall population of women. From Henan, Hebei, Shandong and Shanxi province of China, for each of 50∼99 µg/L, 100∼149 µg/L, 150∼299 µg/L, and ≥300 µg/L water iodine level, three villages were selected respectively. Students of 6–12 years old and pregnant were sampled from villages of each water-iodine level of each province, excluded iodized salt consumer. Then the children's goiter volume, the children and pregnant's urinary iodine and water iodine were tested. In addition, blood samples were collected from pregnant women, lactating women and other women of reproductive age for each water iodine level in the Shanxi Province for thyroid function tests. These indicators should be matched for each person. When the water iodine exceeds 100 µg/L; the iodine nutrient of children are iodine excessive, and are adequate or more than adequate for the pregnant women. It is reasonable to define elevated water iodine areas as locations where the water iodine levels exceed 100 µg/L. The supply of non-iodised salt alone cannot ensure adequate iodine nutrition of the residents, and water improvement must be adopted, as well. Iodine excess increases the risk of certain thyroid diseases in women from one- to eightfold.

Epidemiological investigation on thyroid disease among fertile women in different iodine intake areas of Shanxi province

To understand the prevalence of thyroid diseases and its influencing factors of iodine on thyroid gland function and autoimmune among fertile women in different iodine intake areas. Cross-sectional method was used for descriptive epidemiology. 236 women aged 19 to 45 years were sampled in 2011, in Shanxi province. Questionnaire was used to include general data on place, name, age etc. Sample of water from home, one time random urine sample and venous blood were collected to test the iodine contents using arsenic and cerium catalysis spectrophotometric methods. Finally, in blood, free triiodothyronine (FT3), free thyroxine (FT4), thyrotrophin (TSH) in blood were tested under auto-CLIA and anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-TG) through radio-immunological methods. 1)The urine iodine's medians were 486.9 µg/L for fertile women in high iodine areas, and 192.6 µg/L in low iodine areas, with difference on urine iodine level statistically significant (Z = -10.676, P = 0.000). 2) Levels of blood FT3 and FT4 in women from high iodine areas were obviously lower than those from proper iodine areas(t = -2.884, P = 0.004; t = -2.862, P = 0.005), but the level of TSH in high iodine areas was higher than that of proper iodine areas(t = 2.332, P = 0.021). 3) In both areas, the rate of the thyroid dysfunction with positive antibodies was obviously higher than those with negative antibodies (χ² = 20.941, P = 0.000;χ² = 5.596, P = 0.018), while the rate of the thyroid dysfunction with positive antibodies and the level of TSH in the blood for high iodine women higher than those in women with proper iodine level(χ² = 5.708, P = 0.37;t = -2.177, P = 0.031). 4)The morbidity rate of inferior clinical hyperthyroidism for women in high iodine areas was obviously higher than those in proper iodine areas(χ² = 9.542, P = 0.003), while the morbidity rate of inferior clinical hypothyroidism for women with positive antibodies in two areas obviously higher than those with negative antibodies (χ² = 17.264, P = 0.000; χ² = 6.002, P = 0.044). Morbidity rate of inferior clinical hypothyroidism for women in high iodine areas was obviously higher than those in proper iodine areas, suggesting that there were potential risks of hypothyroidism for overdose iodine intake which causing the existence of positive thyroid antibodies. Monitoring programs on iodine nutrition and thyroid function among women living in high iodine areas should be strengthened.

Long-Term Exposure to Excessive Iodine from Water Is Associated with Thyroid Dysfunction in Children

Previous studies have indicated an association between iodine excess and increased incidence of thyroid dysfunction in adults. However, there have been few studies on how the intake of excessive iodine affects thyroid function in children. The objective of this study was to assess the effects of a long-term exposure to excessive iodine on thyroid dysfunction in children. Urinary iodine concentration (UIC) and thyroid function in 371 children from a high iodine (HI) area (water iodine: 150–963 μg/L) and 150 children from an adequate iodine (AI) area (water iodine: 12.8–50.9 μg/L) were measured. The water iodine concentration in the HI area was higher than that in the AI area (P < 0.001) and the median urinary iodine concentration of children in the HI area was 1030 μg/L, which was 8.6 times that of children in the AI area (123 μg/L) (P < 0.001). Children in the HI area had a higher concentration of sensitive thyroid stimulating hormone and higher positivity of both thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb). The prevalence of thyroid diseases was higher in HI area children than that in AI area children (P = 0.000), especially subclinical hypothyroidism (SCH; P = 0.004). A body mass index (BMI) of ≥22.3 kg/m2 was associated with the incidence of SCH (OR: 5.51; 95% CI: 1.52, 19.9; P = 0.009). UIC ≥600 μg/L (OR: 3.62; 95% CI: 1.22, 10.8; P = 0.024) and TPOAb or TGAb-positivity (Ab+ OR: 6.48; 95% CI: 1.78, 23.6; P = 0.005) in children were significantly and independently associated with SCH. Interactions between UIC ≥800 μg/L and Ab+ (P-interaction = 0.004) were found. Furthermore, increased thyroid volume was correlated with higher UIC (β = 0.22; P = 0.002). Excessive iodine intake in children in HI areas is associated with impaired thyroid function; UIC ≥600 μg/L and Ab+ are the risk factors for SCH. Effective measures need to be taken for reducing excessive iodine intake.

The Hydrogeochemical Characteristics of High Iodine and Fluoride Groundwater in the Hetao Plain, Inner Mongolia

Twenty groundwater samples and two surface water samples were collected to determine the occurrence and distribution of iodine and fluoride in groundwater in the area of Hangjinhouqi, the Hetao Plain, Inner Mongolia. Currently, 65% and 50% of samples exceeded the Chinese standard (I=150μg/L, F=1mg/L) for drinking water for iodine and fluoride, respectively. No correlation has been shown between I and F, although the spatial distribution of high iodine and high fluoride groundwater samples overlaps, with 80% of the high fluoride groundwater samples located in the high iodine areas. Different enrichment mechanisms of fluoride and iodine are involved. Water-rock interaction processes are at the origin of fluoride rich-groundwater, whereas evaporation of shallow groundwater and the oxidation by microorganisms of elevated organic matter content in deep groundwater contribute to the enrichment of iodine.

Study on the iodine status of pregnant women and thyroid function of neonate in high iodine area

To reveal the iodine status of pregnant women and its impact on thyroid function of neonates in high iodine area. A total of 210 pregnant women were chosen from a hospital in Haixing county, Hebei province. Pregnant women's random urinary and neonates' cord blood were collected. The urinary iodine concentration (UIC) was examined by arsenic-cerium catalytic spectrophotometry. The levels of free triiodothyronine (FT3), free thyroxine (FT4) and sensitive thyroid-stimulating hormone (sTSH) in serum were measured by chemiluminescence. The age of 210 pregnant women was (27.69 +/- 4.73) years old, whose urinary iodine median (inter-quartile range ) was 1240.70 (1292.68) microg/L. 84.3% (177/210) of the pregnant women had excessive iodine intake (UIC > or = 500 microg/L), 13.8% (29/210) had more than adequate iodine intake( UIC within 250 - 499 microg/L), 0.5% (1/210) had adequate iodine intake (UIC within 150 - 249 microg/L) and 1.4% (3/210) had insufficient iodine intake (UIC < 150 microg/L). The average serum level of FT3, FT4 in neonates were (2.93 +/- 0.59), (15.03 +/- 1.92) pmol/L, respectively. The median (inter-quartile range) of serum sTSH in neonates were 7.33 (5.59) mU/L 78.1% (164/210) of the neonates' serum TSH were beyond 5 mU/L. There were no correlation between pregnant women's urinary iodine level and neonates' serum FT3 and sTSH level (P > 0.05), but there was a positive correlation between pregnant women's urinary iodine level and neonates' serum FT4 level (P < 0.01). Serum FT4 level of the neonates with whose mothers had insufficient iodine intake ((12.99 +/- 1.10) pmol/L) were statistically lower than those with their mothers had excessive iodine intake (15.16 +/- 1.83) pmol/L) (P < 0.05). Most of the pregnant women in high iodine area were excessive for iodine nutrition, but still a few pregnant women had insufficient iodine nutrition. The level of neonates' serum sTSH were relatively high and monitoring of risk of hypothyroidism and subclinical hypothyroidism should be strengthened.

Investigation of thyroid function abnormalities in children in high water iodine areas of Hebei province

To understand the level of thyroid function and the prevalence of the thyroid diseases of children in high water iodine areas. Two primary schools were selected by purposive sampling from Haixing county, Hebei province in April 2010. A total of 371 children were selected from six classes by cluster sampling in the schools. Morning-urine and venous blood (5 ml) were collected to measure the levels of urinary iodine, free triiodothyronine (FT(3)), free thyroxine (FT(4)) and sensitive thyroid-stimulating hormone (sTSH) in serum and to evaluate the iodine status and thyroid function of children. The median urinary iodine of the children was 1032.08 µg/L. Overall, 96.2% (357/371) of the children's urinary iodine were ≥ 300 µg/L and 68.5% (254/371) were ≥ 800 µg/L. The level of FT(3) and FT(4) were (6.28 ± 0.81) pmol/L and (16.37 ± 2.72) pmol/L, respectively. The median of sTSH was 4.01 mU/L. The FT(4) among boys ((16.63 ± 2.60) pmol/L) was significantly higher than that among girls ((15.99 ± 2.85) pmol/L) (P < 0.05). Overall, 44 subjects were diagnosed as thyroid disease (11.9%), 25 were subclinical hypothyroidism (57% of the total patients), 4 were hypothyroidism (9%), 10 were hyperthyroidism (23%) and 5 were subclinical hyperthyroidism (11%). In the urinary iodine of 200 - 799 µg/L, the prevalence of thyroid disease and hypothyroidism were 6.3% (7/111) and 14.6% (27/254), respectively. When urinary iodine ≥ 800 µg/L, the prevalence of thyroid diseases and hypothyroidism were 3.6% (4/111) and 8.3% (21/254), respectively. Most of the children in high water iodine areas had excessive iodine intake. Levels of the children's thyroid hormone were within the normal range. The prevalence of thyroid disease were high, in these areas and the thyroid disease were mainly the subclinical hypothyroidism.