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

Objective We 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. Methods Based 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. Results The 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. Conclusion Iodine 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.

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.

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.

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.

Iodization of Village Water Supply in the Control of Endemic Iodine Deficiency in Rural Sarawak, Malaysia

A simple water iodizing system, which incorporates the Venturi principle in combination with the controlled release mechanism of a silicone-sodium iodide elastomer, for the iodization of rural piped-water supply in the control of endemic iodine deficiency has been developed and its effectiveness evaluated in three Iban longhouse villages in the iodinedeficient district of Lubok Antu, Sarawak. Urines were collected for iodine assays from women aged 15-40 years before and at 6 and 12 months after the connection of the iodinating device; goiter assessment was performed on the women at the start and end of the 1-year study. Water samples were collected for iodine assays at 2-weekly intervals. In all three villages, significant and sustained increases in median urinary iodine excretions,reaching levels recommended for an iodine-suffcient population, were observed; goitre prevalences were reduced in all the villages (by 22.6% to 35.8%). The iodine levels in the water ranged from 34 μg/l to 212 μg/L. In the control village, median urinary iodine excretions remained essentially unchanged but a small increase in goiter prevalence was observed. The iodized water was well received by the villagers and no adverse effects of water iodization were observed. The system functioned unattended throughout the one year period. The cost of providing supplemental iodine via the iodizing device is approximately 60 cents (U.S.) per family per year which is affordable by either the Government or the villagers. It is concluded that the iodizing system offers a new cost-effective strategy for the control of endemic iodine deficiency in Sarawak and may have applications in other areas with similar water sources

Effects of Maternal Marginal Iodine Deficiency on Interactions between Cerebellar Bergmann Glia Cells and Purkinje Cells in Rat Offspring

Iodine deficiency （ID） during early pregnancy has an adverse effect on children＇s psychomotor and motor function but the mechanism has not been clarified. Therefore, our aim was to study the effect of maternal marginal ID on cerebellar neurodevelopment and the underlying mechanism. After obtaining marginal ID rats, we examined interactions between Bergmann gila cells （BGs） and Purkinje cells （PCs） using immunofluorescence and expression of the glutamate transporter and receptor by western blot. Our results showed that marginal ID reduced the number of contacted points between BGs and PCs,

Iodine deficiency and women’s health: Colonialism’s malign effect on health in Oromia region, in Ethiopia

Objectives: Iodine is an essential nutrient needed for the synthesis of hormone thyroxin. Hormone thyroxin is involved in the metabolism of several nutrients, the regulation of enzymes and differentiation of cells, tissues and organs. Iodine deficiency (ID) impairs the development of the brain and nervous system. It affects cognitive capacity, educability, productivity and child mortality. ID hinders physical strength and causes reproductive failure. The objective of this paper is to explore if the health impacts of ID are more common and severe among women. Design: Using primary data (notes from a visit) and secondary data, this paper examines if the effects of ID are more common and severe among Oromo women inEthiopia. Findings: The health impacts of ID are more common and severe among women. Conclusions: ID is an easily preventable nutritional problem. In Oromia, the persistence of ID is explained by the Ethiopian government’s colonial social policies. Preventing ID should be seen as part of the efforts we make to enhance capacity building, promote health, gender equity and social justice. Implications: Iodine deficiency has a wide range of biological, social, economic and cultural impacts. Preventing ID can be instrumental in bringing about gender equity and building the capacity of people.

Brain Findings Associated with Iodine Deficiency Identified by Magnetic Resonance Methods: A Systematic Review

Objectives: Iodine deficiency (ID) is a common cause of preventable brain damage and mental retardation worldwide, according to the World Health Organisation. It may adversely affect brain maturation processes that potentially result in structural and metabolic brain abnormalities, visible on Magnetic Resonance (MR) techniques. Currently, however, there has been no review of the appearance of these brain changes on MR methods. Methods: A systematic review was conducted using 3 online search databases (Medline, Embase and Web of Knowledge) using multiple combinations of the following search terms: iodine, iodine deficiency, magnetic resonance, MRI, MRS, brain, imaging and iodine deficiency disorders (i.e. hypothyroxinaemia, congenital hypothyroidism, hypothyroidism and cretinism). Results: Up to May 2013, 1673 related papers were found. Of these, 29 studies confirmed their findings directly using MR Imaging and/or MR Spectroscopy. Of them, 28 were in humans and involved 157 subjects, 46 of whom had primary hypothyroidism, 97 had congenital hypothyroidism, 3 had endemic cretinism and 11 had subclinical hypothyroidism. The studies were small, with a mean relevant sample size of 6, median 2, range 1 - 35, while 14 studies were individual case reports. T1-weighted was the most commonly used MRI sequence (20/29 studies) and 1.5 Tesla was the most commonly used magnet strength (6/10 studies that provided this information). Pituitary abnormalities (18/29 studies) and cerebellar atrophy (3/29 studies) were the most prevalent brain abnormalities found. Only fMRI studies (3/29) reported cognition-related abnormalities but the brain changes found were limited to a visual description in all studies. Conclusions: More studies that use MR methods to identify changes on brain volume or other global structural abnormalities and explain the mechanism of ID causing thyroid dysfunction and hence cognitive damage are required. Given the role of MR techniques in cognitive studies, this review provides a starting point for researching the macroscopic structural brain changes caused by ID.

THE MEASUREMENT AND APPLICATION OF TSH－IRMA LEVELS AMONG DIFFERENT AGE GROUPS IN AREAS WITH IODINE DEFICIENCY DISORDERS

Using immunoradiornetric TSH assay (TSH-IRMA) to measure whole blood TSH levels spotted onto filter paper, we compared TSH levels among different age groups (neonates, <1 yr infants, schoolchildren aged 7 to 14 yrs, adults,pregnant women and reproductive-age women) in Guiyang, where iodine deficiency has long been a problem. The results showed: 1) The percentage of subjects with TSH levels equal to or greater than 5 mIU/L in the neonate group was 38.9% while the percentages in the other groups were 0-3.3% (P<0.01); 2)The TSH levels of the neonates were inversely related to the urinary iodine values of their mothers (pregnant women). (r=-0. 5, P<0. 01);3)97.6% of the inhabitants in Guiyang ingested salt with less than 20mg/kg iodine. The results indicate that iodine deficiency remains a problem in Guiyang. Neonates are the only ideal population for monitoring iodine deficiency.

Peculiarities of Morphodensitometric Indices of Epitheliocytes of the Oral Cavity Mucous Membrane in Children with Latent Iron Deficiency and Mild Iodine Deficiency

The article represents the results of the study of the micronutrient deficiency effect(iron and iodine)on the morphometric and optical indices of the oral cavity mucous membrane(OCMM)in school children.In order to achieve this goal,99 school children aged 6-18 years with adequate iodine and iron supply(control group),latent iron deficiency,and mild iodine deficiency were examined.The morphodensitometric study included the determination of the perimeter and area of cells and nuclei,the nuclear-cytoplasmic ratio,the state of chromatin condensation of the epitheliocyte OCMM.The study material was:epitheliocytes of the buccal scraping.It was determined that the area of epitheliocytes in girls aged 6-11 has significantly increased in mild iodine deficiency and in latent iron deficiency.Instead,the decrease of nuclei area was more noticeable in boys of this age in mild iodine deficiency.During the analysis of the general level of chromatin condensation of epitheliocyte nuclei in children,a gender peculiarity has been proved,which was manifested by a greater sensitivity of girls to microelementosis(increase of the integrative optical density of nuclei in the latent iron deficiency at 97.9%,p1-3<0.05,and cell area at 45.8%,p1-4<0.01 relative to control).Among children aged 12-18 years,young men were more sensitive to the deficiency of the studied trace elements.Significant growth of the cell area at 38.7%(p1-2<0.05)in adolescents with mild iodine deficiency and total optical density of nuclei at 63.6%(p1-2<0.05)was substantiated with respect to control in the decrease of karyoplasmic area.

Iodized salt consumption and iodine deficiency status in China: a cross-sectional study

Objective:To monitor iodized salt consumption and evaluate iodine deficiency status in 2014 in China.Materials and Methods:In 2014,a nationwide cross-sectional survey was conducted in 31 provinces (in this study,provinces,autonomous regions and municipalities in China's Mainland were named as provinces).Probability proportional to size sampling method was adopted to recruit children ages 8-10 and pregnant women.47,467 children's and 18,994 pregnant women's urine samples were collected and 47,706 children's thyroid volumes were examined.Iodine content in salt was determined with 46,900 edible salt samples from children's households;urinary iodine concentration (UIC) was tested from children and pregnant women's urine samples;thyroid volume of children was assessed by ultrasound.Results:The national coverage rate of iodized salt and consumption rate of qualified iodized salt were 96.3％ and 91.5％,respectively.Median iodine content in iodized salt was 25.2 mg/kg.In 22 of 31 provinces,the provincial coverage rates of iodized salt were over 95％.And consumption rates of qualified iodized salt were more than 90％ in 21 provinces.In this study,the national median urinary iodine concentration (MUIC) of children in China was 197.9 μg/L.At the provincial level,MUIC of children in 19 provinces was 100-199 μg/L,which in 12 provinces was 200-299 μg/L.The national MUIC of pregnant women in 2014 was 154.6 μg/L,slightly higher than the lower limit of the WHO criteria for adequate (150-249 μg/L).At the provincial level,MUIC of pregnant women in 18 provinces was 100-149 μg/L,which in 13 provinces was 150-249 μg/L.The national prevalence of goiter among children in 2014 was 2.6％,of which only Shandong province (5.6％) exceeded the national standard (5％).Conclusions:In China,iodine deficiency disorders (IDD) has been eliminated since 2005.And in 2014,the IDD-free status still remained.

Effect of Selenium Supplementation on Activity and mRNA Expression of Type 1 Deiodinase in Mice With Excessive Iodine Intake

Objective To investigate the effect of selenium supplementation on the selenium status and selenoenzyme, especially the activity and mRNA expression of type 1 deiodinase （D1） in mice with excessive iodine （EI） intake and to explore the mechanism of selenium intervention on iodine-induced abnormities. Methods Weanling female BALB/c mice were given tap water or 3 mg/L of iodine or supplemented with 0.5 mg/L or 1.0 mg/L of selenium in the presence of excessive iodine for 5 months. Selenium status, thyroid hormone level, hepatic and renal D 1 activity and mRNA expression were examined. Results Excessive iodine intake significantly decreased the selenium concentration in urine and liver, and the activity of glutathione peroxidase （GSH-Px） in liver. Meanwhile, serum total T4 （TT4） increased while serum total T3 （TT3） decreased. Hepatic D1 enzyme activity and mRNA expression were reduced by 33% and 86%, respectively. Renal D1 enzyme activity and mRNA were reduced by 30% and 55%, respectively. Selenium supplementation obviously increased selenium concentration, activity of GSH-Px and D1 as well as mRNA expression of D1. However, increasing the supplementation of Se from 0.5 to 1.0 mg/L did not further increase selenoenzyme activity and expression. Conclusion Relative selenium deficiency caused by excessive iodine plays an essential role in the mechanism of iodine-induced abnormalities. An appropriate dose of selenium supplementation exercises a beneficial intervention.

Effect of Excessive Iodine on Immune Function of Lymphocytes and Intervention with Selenium

In order to study the effect of excessive iodine on immune function of lymphocytes and the role of selenium supplementation with excessive iodine intake, the changes of T lymphocyte number, ratio of subsets, activity of natural killer （NK） cells and lymphocytes proliferation response were investigated. 150 female BALB/C mice were randomly divided into 5 groups in terms of their body weight （n=30 in each group）, and 10 of each group were taken as one batch for test. Mice in the 5 groups were orally administrated with iodine 0 （group Ⅰ ）, 1500 （group Ⅱ）, 3000 （group Ⅲ）, 6000 μg/L （group ）, iodine 6000 μg/L plus selenium 0.3 mg/L （group Ⅴ） respectively for 30 days. Lymphocyte proliferation response, CD4^＋/CD8^＋, Th1/Th2 and the activity of NK cells were measured. CD4^＋/CD8^＋ was significantly lower, while lymphocyte proliferation response stronger, and Th1/Th2 and the activity of NK cells significantly higher in group Ⅳ than in group Ⅰ （P〈0.01）. There was no significant difference in all indexes between group Ⅴ and group Ⅰ （P〉0.05）. It was suggested that excessive iodine as exogenous chemical materials can induce disorders of T lymphocyte immune function in mice. 0.3 mg/L selenium supplementation can protect mice against toxicity induced by 6000 μg/L iodine.

Excess iodine exposure:An emerging area of concern for male reproductive physiology in the post-salt iodization era

To prevent iodine deficiency disorders,the universal salt iodization programme has been introduced all over the globe,including environmentally iodine sufficient regions irrespective of their iodine status.As a result,iodine-induced thyroid dysfunctions namely hyperthyroidism,hypothyroidism,autoimmune thyroid diseases,endemic goiter and even thyroid cancer including infertility,still births,abortions and embryo toxicity have emerged as a major public health problem.In other words,the consequence of iodine deficiency and excess is almost‘U’-shaped.Hypothyroidism caused by iodine deficiency affects reproductive functions of organisms;however,such undesirable effects of iodine overload on male gonadal physiology together with hormonal profiles are yet to be adequately explored.The discovery of iodide transporter in the testis justifies an independent role of iodine in male reproductive function,which is not entirely known.Recent studies on human subjects and animal models are now revealing further perceptions into the effect of excess iodine on male infertility with euthyroid status.Excess iodine exposure has been linked with deterioration of structural and functional changes of testis leading to compromised spermatogenesis by affecting various cellular and molecular signaling pathways culminating into disrupted the blood-testis barrier and cytoskeleton.This review provides an update and summarizes various novel insights of excess iodine exposure on reproduction by establishing the independent role of iodine on male reproductive endocrinology,which might help in formulating future strategies to prevent iodine-induced male infertility,an emerging global concern,especially in the post-salt iodization era.

Selenium and Iodine Deficiencies and Selenoprotein Function

This paper reviews some recent findings on the interactions between selenium deficiency and iodine deficency. Both micronutrients can control the levels of selenoprotein mRNAs, particularly in the thyroid and brain. When selenium and iodine supplies are limiting the compensatory mechanisms work to minimise adverse effects on thyroid hormone metabolsm and thus neurological developtnent. The mechanisms for regulation of selenoproteins in selenium and iodine deficiency are however very tissue-specific. For example, unlike the brain and thyroid,brown adipose tissue is unable to retain selenoproteins in selenium and iodine deficiency and is therefore at greater risk from injurious effects of the deficiencies.

Studies on the Free Radicals and Thyroid Hormone Metabolism in Cattle with Iodine and Selenium Deficicncy

In order to interpret pathologic mechanism of free radicals and thyroid hormone metabolism in cattle iodine and selenium deficiency, 20 heads of yellow cattle were selected from NiuJia town, Wu Chang City, Heilongjiang Province, China, and were randomly devided into 4 groups with 5 for each. ① supplemented with 0.7 mg·kg -1 iodine(potassium iodine), ② supplemented with 0.2 mg·kg -1 selenium (sodium selenite), ③ supplemented with 0.7 mg·kg -1 iodine(potassium Iodine) plus 0.2 mg·kg -1 selenium (sodium selenite) per day for 30 days, respectively. ④control group. The whole blood glutathione peroxidase (GSH-px) and catalase (CAT) activities, free radicals (FR) concentration, erythrocyte superoxide dismutase (SOD) activity and molonaldehyde (MDA) concentration, the serum triiodothyronine (T 3)、thyroxine (T 4) and thyrotropin (TSH) were determined on the day of supplementation day-0 and day-30, respectively. It was showed that average iodine concentration in drinking water and diet were 3.82 μg·L -1 and 0.285mg·kg -1 , respectively, Diet selenium was 0.0498mg·kg -1 , Serum protein bound iodine(PBI) was 7.02 μg·100 mL, Blood selenium was 0.14 mg·L -1 , the schoolchildren′s goiter was 21.8%. It indicated that iodine and selenium were deficient in the investigated area. Whole blood GSH-px and CAT activities and serum T 3 concentration were significantly higher (P< 0.01 ), FR concentration and serum TSH were significantly lower(P<0.01) in the first three groups than that of the control, T 4 content in the first group was higher(P<0.05), T 4 was also higher (P>0.05) in the second group. and lower in the third group. The SOD and MDA in erythrocyte were not changed during the experimental period, The results also showed that GSH-px and CAT activities were increased, and FR decreased oberviously in the third group more than the other two groups, In addition, Thyroid hormone metabolism was more coincided with the physiologic status in the third group. the iodine and the selenium played an important role in the pathologic process of free radical metabolic disorder. selenium not only had the function of antioxidation by derectly scavenging free radicals, but also affected through GSH-px and CAT activities. iodine deficiency results in the Goiter, selenium deficiency aggravated iodine deficiency, Iodine and the selenium were dependent and restrained each other in the course of free radicals and thyroid hormone metabolism with a synergistic state.

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.

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.

Effects of High Fluoride and Low Iodine on Thyroid Function in Offspring Rats

Thirty-two Wistar rats were divided randomly into four groups of eight with six females and two males in each group. The rats were exposed to high fluoride drinking water （45 mg F-L^-1 from 100 mg NaF L-1）, low dietary iodine （0.0855 mg kg-1）, or both together in order to assess the effects of these three regimens on the thyroid function of the offspring rats. After the animal model was established, the offspring rats were bred and 10-, 20-, 30-, 60-, and 90-d-old rats were used for the experiment. The treatments for the offspring rats were the same as those of their parents. In comparison with control rats, the relative thyroid glands were changed by three regimens, but the mean values of thyroid weight in the experimental groups saw no marked difference. Serum TT3 levels were increased in all stages in the low iodine （LI） group. In the high fluoride （HiF） group, increase in TT3 levels was observed except in 20-d-old rats. Decrease in TT3 at 20- and 90-d and increase in TT3 at 30- and 60-d were found in HiF＋LI group. Serum TT4 levels first saw an increase, and then dropped in the LI and HiF＋LI group. However, an increase in TT4 was found in the HiF group. The levels of TSH in serum rocketed at d 20, and then dropped in the next stages in experimental groups. The results suggested that thyroid disorder could be induced by high flroride in drinking water, low iodine diet, or both of them. Exposure time to fluoride or low iodine diet was one of the important factors that fluoride can induce the development of thyroid dyfunction.

Iodine Malnutrition and Associated Factors in Schoolchildren Aged 6 to 14 Years in a Municipality Situated in the Semi-Arid Region of the State of Minas Gerais, Brazil, 2008

The objective of this study was to assess the prevalence of iodine deficiency and possible correlated factors among schoolchildren in the municipality of Novo Cruzeiro-MG by means of an evaluation of urinary iodine excretion. Five hundred and forty schoolchildren aged 6 to 14 years selected by stratified sampling, were evaluated. Urine samples were analyzed using the Sandell-Kolthoff method preconized by the WHO and iodine concentrations in the salt were assessed by means of volumetric analysis, in accordance with recommendations from the Ministry of Health. Iodine deficiency was observed in 38.9% of the schoolchildren. Of these, 28.7% of them presented slight deficiency, 6.2% of them were moderately deficient and 4% of them were seriously deficient. Median urinary iodine levels in the urban and rural population were 150.8 and 119.2 μg/L, respectively, with a clear distribution of iodine deficiency among the populations (p < 0.001) being registered. It was also observed that there was a high prevalence of deficient urinary iodine excretion among schoolchildren that consumed salt with an insufficient iodine content. In relation to the quality of the salt consumed by families, in 12.2% of the residences studied the iodine content in salt was below the recommended level (20 mg/kg), while the iodine content was below 15 mg/kg in only 5.3% of them. The results indicated that, although not characterized as a public health issue, according to WHO criteria, iodine deficiency showed very high prevalence among schoolchildren in this region. Regarding the iodine content of salt found in household consumption, our findings indicated the National Program of Salt Iodination was not efficient in the city, since it did not hit the target proposed by the Ministry of Health. Furthermore, low urinary iodine excretion associated with the consumption of salt with low iodine content suggests the need for periodical evaluations in order to provide effective control of the endemic disease.