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.

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 up-regulates monocarboxylate transporter 8 expression of mouse thyroid gland

Background Iodine deficiency is a major factor affecting thyroid auto-regulation,the quantity of iodine may greatly influence the synthesis of thyroid hormones （THs）.It has long been believed that TH enters the cell through passive diffusion.Recent studies have suggested that several transporters could facilitate transportation of TH.The monocarboxylate transporter 8 （MCT8） was identified as a very active and specific TH transporter.The purpose of this study was to investigate whether iodine insufficient affected the expression of MCT8 in the thyroid gland.Methods Sixty BALB/c mice were randomly divided into two groups：control group was fed with standard feed （iodine concentration of 300 μg/kg）; while low-iodine （LI） group received iodine-insufficient feed （iodine concentration of 20-40 μg/kg）.After 3 months,10 mice of each group were sacrificed.The remaining 20 mice of each group were kept till 6 months.From the LI group,we randomly selected 15 mice and injected triiodothyronine （T3,100 μg/kg body weight per day） intraperitoneally for 24,48 or 72 hours （5 mice for each time-point）.Then,all the mice were sacrificed.Mouse serum thyroxine （T4）,T3,and thyroid-stimulating hormone （TSH） levels were determined by chemiluminescence immunoassay （CIA）.The protein content or messenger RNA （mRNA） level of thyroid MCT8 was measured by Western blotting analysis or real time RT-PCR respectively.MCT8 subcellular location in thyroid tissues was probed with immunohistochemistry （IHC） assay.Results We found that mouse serum T3 and T4 levels decreased and TSH level increased by the end of the third month.Consistent with these findings,there was significant goiter and hypothyroidism in the LI group.Meanwhile,the MCT8 mRNA increased to 1.36-fold of the level in the control group at the 3rd month.At 6th month,the serum T4 level in LI mice remained at a lower level,and MCT8 mRNA expression continued rising to nearly 1.60-fold compared with the control group.The protein content was also about 3 times higher than that in the control group.IHC results also revealed MCT8 was of higher expression and localized in the cytoplasm of thyroid follicular cells.After providing exogenous T3 to iodine deficient mice,the serum T3 and T4 gradually increased,whereas MCT8 mRNA and protein both started to decrease and returned to the same level as the control group.Conclusion There is a compensatory increase in thyroid MCT8 expression to enhance its capability to transport TH from thyroid to the blood circulation in iodine deficient mice.

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.

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.

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.

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.

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.

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.

Cyanide Contents of Leaves of Commonly Consumed Cassava Varieties from Three Geographical Regions of Ghana

Consuming a cyanogenic plant is an etiological factor to the persistence of iodine deficiency in the post salt iodization phase. Ghana, notably the Northern belt, still reports of iodine deficiency after 14 years of mandatory consumption of iodized salt by an Act of Parliament. The study aimed at determining the cyanide contents of leaves of commonly consumed cassava varieties in Ghana and investigating the effects of some environmental factors on cyanide content. Three communities each from Southern, Middle and Northern Ghana served as the study sites from where young, non-diseased and fully-spread cassava leaves were sampled from plants of commonly consumed cassava varieties. Cyanide was analyzed by the standard color^metric method based on the chloramine-T/pyridine-barbituric acid protocol （4500-CN E）. Cassava leaves from Northern Ghana had significantly higher mean cyanide content （177.22 ± 20.82 ppm） than those from Middle （130.83± 33.00 ppm） and Southern Ghana （127.24 ± 37.54 ppm） （P 〈 0.001）. Two-factor ANOVA showed significantly higher adverse environmental effects on cyanide contents of leaves of unimproved cassava varieties than improved ones （R2 = 0.627, P = 0.023）. From multiple regression analysis, temperature was the most significant environmental factor explaining 33% of the variability in cyanide content （R2 = 0.331, P = 0.002）, followed by altitude （R2 = 0.106, P = 0.049） and rainfall （R2 = 0.084, P = 0.062）. The high cyanide contents of cassava leaves from Northern Ghana, due principally to the high atmospheric temperature, may be a contributory factor to the high prevalence of goiter and the persistence of iodine deficiency in that geographic region.

Non-radical activation of persulfate with Bi_(2)O_(3)/BiO_(1.3)I_(0.4)for efficient degradation of propranolol under visible light

Non-radical activation of persulfate(PS)by photocatalysts is an effective approach for removing organic pollutants from aqueous environments.In this study,a novel Bi_(2)O_(3)/BiO_(1.3)I_(0.4)heterojunction was synthesized using a facile solvothermal approach and used for the first time for non-radical activation of PS to degrade propranolol(PRO)in the presence of visible light.The findings found that the degradation rate of PRO in the Bi_(2)O_(3)/BiO_(1.3)I_(0.4)/PS system was significantly increased from 19%to more than 90%within 90 min compared to the Bi_(2)O_(3)/BiO_(1.3)I_(0.4)system.This indicated that the composite system exerted an excellent synergistic effect between the photocatalyst and the persulfate-based oxygenation.Quenching tests and electron paramagnetic resonance demonstrated that the non-radical pathway with singlet oxygen as the active species played a major role in the photocatalytic process.The existence of photo-generated holes during the reaction could also be directly involved in the oxidation of pollutants.Meanwhile,a possible PRO degradation pathway was also proposed.Furthermore,the impacts of pH,humic acid and common anions on the PRO degradation by the Bi_(2)O_(3)/BiO_(1.3)I_(0.4)/PS were explored,and the system’s stability and reusability were also studied.This study exhibits a highly productive catalyst for PS activation via a non-radical pathway and provides a new idea for the degradation of PRO.

Type 1 iodothyronine deiodinase activity and mRNA expression in rat thyroid tissue with different iodine intakes

Background Type 1 deiodinase （D1） plays an important role in the metabolism of thyroid hormone and has close relationship with thyroid function. In this study we explore the effects of iodine intake on D1 activity and its mRNA expression and its possible mechanism. Methods Forty-eight Wistar rats were randomly divided into six groups with 8 in each： low iodine （LI）, normal iodine （NI）, five-fold iodine （HI5）, ten-fold iodine （HI10）, fifty-fold iodine （HI50）, one hundred-fold iodine （HI100） group. Three months, six months and twelve months after admistration of potassium iodate, they were sacrificed and thyroids were excised. The expression of D1 mRNA in the thyroid tissue was determined by RT-PCR and D1 activity was analyzed by ^125I-rT3 as substrate. The thyroid hormone was measured with radioimmunoassay method. Results Compared with NI group, D1 mRNA expression in LI groups slightly decreased, and D1 activity greatly increased. Both T3 and T4 in thyroid tissue significantly decreased, but the T3/T4 ratio increased. D1 mRNA expression decreased in all HI groups, and D1 activity was significantly lower in HI groups. There was a tendency of decrease in D 1 activity with increased doses of iodine intakes. There was no significant difference in T4 in thyroid tissue between HI groups and NI group, but a tendency of decrease in T3 level was found in all HI groups. Conclusions In the case of iodine deficiency, D 1 activity increased greatly in order to convert more T4 to T3. Excess iodine can inhibit both D1 mRNA expression and its activity to protect organism from being injured by excessive T3.

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.