Research progress on the relationship between iodine, thyroid function and lipid metabolism / 中华地方病学杂志

Iodine is an essential component of thyroid hormone biosynthesis. It plays an important role in the growth, development, maturation and the function of organs and systems. Epidemiological and animal studies have shown that the effect of iodine on human body is bidirectional. Insufficient and excessive intake of iodine will cause adverse consequences and affect human health. At present, the research on the harm of iodine nutritional abnormalities to human health mostly focuses on morphology and function of thyroid. In fact, iodine nutritional abnormalities not only affect thyroid, but also have many adverse effects on other aspects of the body. There is evidence of a link between abnormal iodine nutrition, dyslipidemia and cardiovascular disease, which will lead to abnormal levels of triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol in the body. This paper reviews the research progress on the relationship between iodine nutrition, thyroid function and body lipid metabolism, in order to provide a theoretical basis for the "scientific and precise" prevention and treatment of iodine deficiency disorders in China.

Observation on iodine metabolism in milk of lactating rats with different iodine nutritional levels / 中华地方病学杂志

Objective:To observe the urinary iodine content (UIC), breast milk iodine content (BMIC) and milk iodine excretion of lactating rats under different iodine nutrition levels, and to explore the iodine metabolism of the lactating rats under different iodine nutrition levels.Methods:Forty female Wistar rats with body weight ranging from 70 to 120 g were divided into low iodine (LI) group, normal iodine (NI) group, hight iodineⅠ (HIⅠ) group and hight iodine Ⅱ (HIⅡ) group according to body weight by random number table method, with 10 rats in each group. The rats were fed low-iodine diet, and the iodine ion concentration of drinking water in each group was 0, 325, 18 700 and 37 450 μg/L. Twenty male rats were fed according to the feed method of NI group. After 8 weeks of intervention, the male and female rats were caged and mated in a ratio of 1 ∶ 2. Milk and 24 h urine were collected on the 7th, 14th and 21st days of lactation (L7, L14 and L21), and the amount of food and drinking water consumed were recorded. The 24 h milk excretion was calculated by acute lactation test. UIC and BMIC were determined by inductively coupled plasma mass spectrometry (ICP-MS).Results:The 24 h total iodine intake of lactating rats in LI, NI, HIⅠ and HIⅡ groups were (1.84 ± 0.51), (30.51 ± 6.79), (765.95 ± 317.41) and (1 654.26 ± 560.55) μg/d, respectively. The difference between groups was statistically significant ( P < 0.001). At L7, L14 and L21, there were statistically significant differences in UIC, BMIC and milk iodine excretion at the same lactation stages among different groups ( P < 0.001). In HIⅡ group, the difference of BMIC and milk iodine excretion at different lactation stages (L7, L14, and L21) were significantly signrficant ( P < 0.05). The 24 h milk iodine excretion of LI, NI, HIⅠ and HIⅡ groups was (1.23 ± 0.85), (11.88 ± 5.23), (207.09 ± 114.51), (493.67 ± 242.47) μg, respectively. The proportion of 24 h milk iodine excretion to 24 h total iodine intake was 66.85%, 38.94%, 27.04% and 29.84%, respectively. Conclusions:About 39% of dietary iodine is supplied to offspring through milk when iodine nutrition is normal. The iodine excretion ratio of milk is increased or decreased with low and high iodine levels. These results indicate that lactating rats with different iodine nutrition levels can regulate the ratio of iodine excretion in milk through their own compensatory effect to reduce the influence of iodine deficiency and iodine excess on their offspring.

Effect of Chronic Iodine Excess on Type Ⅱ Deiodinase in Hypothalamus and Serum Thyrotropin Releasing Hormone Level in Rats / 中国医科大学学报

Objective To investigate the effect of chronic iodine excess on hypothalamic type Ⅱ deiodinase (D2) and serum thyrotropin releasing hormone (TRH) levels in rats. Methods One hundred and eighty four-week-old Wistar rats were randomly divided into control group (NI) and 3-fold, 6-fold, 10-fold, and 50-fold high iodine (HI) groups. Double distilled water and iodine solutions at concentrations of 277, 692, 1 245, and 6 788 μg/L were administered for 4, 8, 12, and 24 weeks, respectively. Brain tissue was taken after sacrifice, serum TRH levels were detected by ELISA, and hypothalamic D2 levels were detected by immunohistochemistry. Results Serum TRH levels in the 10-fold and 50-fold HI groups at 4 weeks, 6-fold and 50-fold HI groups at 8 weeks, 6-fold HI group at 12 weeks, and the 3-fold and 50-fold HI groups at 24 weeks were significantly lower than those in the control group (P ＜ 0.05). The results of immunohistochemistry revealed that the expression of hypothalamic D2 at each time-point was increased in the HI groups in comparison with the control group. Conclusion Chronic iodine excess can boost the expression of hypothalamic D2 and lessen the serum TRH level in rats.

Advances in the relationship between iodine and thyroid carcinoma / 中华地方病学杂志

In recent years,the incidence rates of thyroid carcinoma (TC) in many countries have been increasing rapidly,especially papillary TC.But the reasons are not yet unified.The main influencing factors include improved diagnosis methods,increased screening,radiation exposure,mental stress,body mass index (BMI) and obesity.The role of iodine intaken in TC remains uncertain.It is generally believed that iodine deficiency is a risk factor for follicular TC;and excessive iodine intake can rise the constituent ratio of papillary TC.

"An interpretation of the newly revised standard on ""Definition and Demarcation of Water-borne Iodine-excess Areas and Iodine-excess Endemic areas""" / 中华地方病学杂志

In order to solve some limitations and difficulties in guiding the practical work of determination and classification of the areas of high water iodine and the endemic areas of iodine excess goiter (GB/T 19380-2003),we carried out the revision on the original standard from 5 aspects such as the name,normative reference file,the definition and the technical indicators of classification of high iodine areas and the endemic areas of iodine excess goiter,such as sampling method in appendix and so on,and worked out the standard of definition and demarcation of water-borne iodine-excess areas and iodine-excess endemic areas.Enforcement of the new standard will bring important social benefits.

National monitoring results in high water iodine areas in 2015 / 中华地方病学杂志

Objective To observe the high iodine induced thyroid goiter condition,iodine nutritional status and coverage rate of non-iodized salt in high water iodine areas.Methods The household non-iodized salt was monitored in counties (cities,regions) of high water iodine areas and high iodine diseased areas in Tianjin,Hebei,Shanxi,Jiangsu,Anhui,Shandong,Henan and Shaanxi provinces.Among the monitoring sites,where the water iodine were 150-300 μg/L or higher than 300 μg/L,50％ of the them were selected to investigate the water iodine,children urinary iodine and thyroid volume of children in high iodine counties.Results Household edible salt was monitored in 110 counties of 8 provinces,with a total of 25 597 salt samples.The number of non-iodized salt was 24 640,and the coverage rate of non-iodized salt was 96.3％.After being weighted based on the population of counties,the coverage rate of non-iodized salt was 96.9％.In all,73 survey areas include 183 663 people,64 monitoring sites (87.7％) where the water iodine level were higher or equal to 150 μg/L and the median of water iodine was 250.8 μg/L.Totally 5 991 children aged 6-12 were measured thyroid volume,the total goiter rate was 6.2％,the children thyroid goiter rate was higher than 5％ in Hebei,Shanxi,Henan,Tianjin and Shandong provinces.Totally 4 618 children were detected urinary iodine,the median urinary iodine concentration was 373.0 μg/L,and the children median urinary iodine concentration was exceeded 300 μg/L in Tianjin,Hebei,Shanxi,Jiangsu and Shandong provinces.The children urinary iodine concentration and goiter rate increased gradually with increasing of water iodine content.Conclusions The non-iodized salt coverage rate is high in high water iodine areas,most monitored areas have changed drinking water sources,but the median water iodine concentration is still higher than 150 μg/L.Children median urinary iodine concentration is higher than 300 μg/L,iodine is in a excessive status.The children total goiter rate is higher than 5％.Some countermeasures are proposed to search low iodine water,change water sources,do health education,and add other surveillance measures,such as thyroid function detection on target groups,and so on.

National monitoring results in high water iodine areas in 2015 / 中华地方病学杂志

Objective To observe the high iodine induced thyroid goiter condition,iodine nutritional status and coverage rate of non-iodized salt in high water iodine areas.Methods The household non-iodized salt was monitored in counties (cities,regions) of high water iodine areas and high iodine diseased areas in Tianjin,Hebei,Shanxi,Jiangsu,Anhui,Shandong,Henan and Shaanxi provinces.Among the monitoring sites,where the water iodine were 150-300 μg/L or higher than 300 μg/L,50％ of the them were selected to investigate the water iodine,children urinary iodine and thyroid volume of children in high iodine counties.Results Household edible salt was monitored in 110 counties of 8 provinces,with a total of 25 597 salt samples.The number of non-iodized salt was 24 640,and the coverage rate of non-iodized salt was 96.3％.After being weighted based on the population of counties,the coverage rate of non-iodized salt was 96.9％.In all,73 survey areas include 183 663 people,64 monitoring sites (87.7％) where the water iodine level were higher or equal to 150 μg/L and the median of water iodine was 250.8 μg/L.Totally 5 991 children aged 6-12 were measured thyroid volume,the total goiter rate was 6.2％,the children thyroid goiter rate was higher than 5％ in Hebei,Shanxi,Henan,Tianjin and Shandong provinces.Totally 4 618 children were detected urinary iodine,the median urinary iodine concentration was 373.0 μg/L,and the children median urinary iodine concentration was exceeded 300 μg/L in Tianjin,Hebei,Shanxi,Jiangsu and Shandong provinces.The children urinary iodine concentration and goiter rate increased gradually with increasing of water iodine content.Conclusions The non-iodized salt coverage rate is high in high water iodine areas,most monitored areas have changed drinking water sources,but the median water iodine concentration is still higher than 150 μg/L.Children median urinary iodine concentration is higher than 300 μg/L,iodine is in a excessive status.The children total goiter rate is higher than 5％.Some countermeasures are proposed to search low iodine water,change water sources,do health education,and add other surveillance measures,such as thyroid function detection on target groups,and so on.

Iodine excess and its effects on human health / 中华地方病学杂志

Iodine is an essential trace element,its physiological function is realized through thyroid hormone,both iodine deficiency and excess have influences on human health.After 20-year implementation of universal salt iodization in China,the iodine deficiency disorders have been controlled effectively,while the problem of iodine excess emerged.Because of different geographical environment,dietary habits and physiological status,some people did exposed to high level of iodine.In recent years,domestic and foreign scholars carried out series of researches aiming at disclose the effects of iodine excess on human health.The health problems induced by high iodine intaking are goiter,hyperthyroidism,hypothyroidism,autoimmune thyroiditis and thyroid cancer et al.Therefore,when preventing and treating iodine deficiency,iodine excess should also be avoided,so as to achieve the ideal goal of adjust measurements according to local conditions,classification guidance,and scientific iodine supplementation.

Iodine intake and thyroid disease / 中华地方病学杂志

Iodine is a micronutrient that is essential for the production of thyroid hormones.Either iodine deficiency or excess will not only affect the synthesis and secretion of thyroid hormone but also be related to the occurrence and development of thyroid diseases.Iodine deficiency can cause endemic goiter,cretinism,hypothyroidism and thyroid cancer;high incidence of hyperthyroidism,hypothyroidism,autoimmune thyroid disease,goiter,and thyroid cancer are associated with excessive iodine intake.It is essential to assess iodine nutritional status for the populations,particularly those with thyroid diseases.

Study on the effectiveness of withdrawing iodized salt on preventing iodine excess in the population in high iodine areas / 中华地方病学杂志

Objective To access the effectiveness of withdrawing iodized salt on correcting the iodine excess in the population living in high iodine areas.Methods Before withdrawing iodized salt,2 twons were selected from each of 5 cities with water-borne iodine excess areas in Hebei province.All the selected towns were divided into 7 groups according to their iodine content in drinking water.Two villages wereselected from each group where urine samples of children aged 8 to 10 years old were collected to investigate the change of urinary iodine content of these children before and after withdrawing iodized salt.The urinary iodine content was determined using the method for determination of ammonium persulfate digestion arsenic cerium catalytic spectrophotometry (WS/T 107-2006).Correlation between children's urinary iodine and drinking water iodine was analyzed.Results Before and after withdrawing iodized salt,744 and 771 urine samples were collected from the examined children aged 8-10 years respectively.The overall median urinary iodine content (MUIC) of the examined children after withdrawing iodized salt (350.1 μg/L) decreased significantly than that of before withdrawing iodized salt (460.8 μg/L,U =3 127.8,P ＜ 0.05).After withdrawing iodized salt,the MUIC of the children decreased significantly in 8 of 12 villages (P ＜ 0.05).Before and after withdrawing iodized salt,the percentage of urine samples with iodine content above 300 μg/L was 76.7％ (571/744),58.5％ (451/771) respectively,with significant statistical difference (x2 =57.7,P ＜ 0.05).After withdrawing iodized salt,Children's MUIC also decreased significantly across gender and age (boys:558.5,351.6 μg/L,U =960,P ＜ 0.05; girls:522.9,355.5 μg/L,U =698,P ＜ 0.05; 8 years old:536.0,295.5 μg/L,U =529.5,P ＜ 0.01; 9 years old:386.2,323.2 μg/L,U =753.5,P ＜ 0.01; 10 years old:525.5,368.8 μg/L,U =521.5,P ＜ 0.05).The children's MUIC correlated positively with the median water iodine contert (MWIC) in the villages where they lived (r =0.951,P ＜ 0.01).Analyzed by linear regression,approximately 89％ of the variability in MUIC was associated with variability in MWIC.Conclusions Withdrawing iodized salt could only correct the iodine excess caused by consuming iodized salt in the population living in the areas with MWIC below 100 μg/L.In the areas with water iodine above 100 μg/L,intervention should be focused on seeking water with proper iodine content.

Meta-Analysis on the relationship between children,s high iodine goiter and excessive iodine / 重庆医学

Objective To comprehensively evaluate the relationship between children's high iodine goiter and excessive iodine . Methods A computerized literature search was carried out to collect articles published before 2014 in electronic databases CBM , WabFang ,VIP ,CNKI ,PubMed ,EMbase ,Ovid and Cochrane Library .The study type was randomized controlled trial or quasi‐ran‐domized control trial .Literature was analyzed by RevMan5 .0 software ,then calculated and combine RR and 95% CI .Publication bi‐as of Meta analysis was evaluated by Begg's test ,Egger's test and Macaskill's test .The result stability of Meta analysis was tested by sensibility analysis .Results A total of 10 controlled before and after studies were included in our meta‐analysis .The result showed that the iodine content of 150 -300 μg/L (RR:1 .54 ;95% CI:1 .14 -2 .07);301 -600 μg/L (RR:2 .33;95% CI:1 .43 -3 .82);601-900 μg/L (RR:2 .72 :95% CI:1 .01-7 .33) and greater than 900μg/L (RR:2 .41 ;95% CI:1 .38-4 .23) would result in chil‐dren goiter .Conclusion Iodine content greater than 150 μg/L would result in children goiter .

Urinary iodine excretion in healthy Mexican adults / Excreción urinaria de yodo en adultos sanos mexicanos

The iodine nutritional status of a population is mainly measured by urinary iodine excretion (UI) and thyroid volume determined by ultrasound (US). The surveillance of nutritional iodine levels in the Mexican population has been insufficient. Our aim was to determine the UI in random samples from adults living in an urban area. We selected a sample of healthy individuals over the age of 18 that were students, physicians or administrative personnel at our Institution and had no known thyroid disease. Thyroid volume was determined by ultrasound in all volunteers as well as thyroid hormones and antithyroid antibodies and a urine sample was obtained. One hundred and two volunteers with a median age of 29, participated in the study. The group’s median UI was 221 μg/L,interquartile range (IQR)(135.0 to 356.8) and no differences were observed between genders: women had a UI of 218.0 μg/L IQR (129.0 a 351.0) vs. 223.0 μg/L IQR (138.0 to 374.0) in males, p 0.941. Excessive dietary iodine intake was established in 31.4% of all volunteers according to their UI, placing them at risk of thyroid dysfunction. It is fundamental to evaluate the national iodine nutritional status in Mexico. We discuss the current status of the nutritional state in the Americas, emphasizing that in Latin America and the observed tendency in the region to ingest a diet high in iodine.

El estatus nutricional del yodo en una población, principalmente es medido por la excreción del yodo urinario (UI) y el cálculo del volumen tiroideo por ultrasonido (US). La vigilancia nutricional del yodo en la población en México ha sido escasa. El objetivo fue determinar la UI en una muestra casual en adultos sanos que habitan en un área urbana. Se seleccionó una muestra de individuos mayores de 18 años, entre estudiantes, médicos y trabajadores administrativos de nuestra institución, sanos, sin enfermedad tiroidea conocida. A todos los voluntarios se les determinó el volumen tiroideo por US, hormonas y anticuerpos antitiroideos y se les solicitó una muestra de orina. Participaron 102 voluntarios, mediana de 29 años. La mediana de la UI del grupo fue 221 μg/L, rango intercuartílico (RIQ) (135.0 a 356.8), no hubo diferencias entre géneros, las mujeres tuvieron una UI de, 218.0 μg/L RIQ (129.0 a 351.0) vs 223.0 μg/L RIQ (138.0 a 374.0) p 0.941. El 31.4% de los voluntarios mostraron una ingestión excesiva de yodo en la dieta de acuerdo a la UI, lo cual los coloca en riesgo de sufrir disfunción tiroidea. Es necesario considerar la evaluación Nacional del estatus nutricional del yodo, en México. En el artículo se discute la situación actual del estatus nutricional en las Américas, haciendo énfasis en Latinoamérica y a la tendencia de la región a la dieta excedida en yodo.

Effects of Increased Iodine Intake on Thyroid Disorders

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

Iodine Intake and Tolerable Upper Intake Level of Iodine for Koreans

The present study reviewed the effects of excess iodine intake on thyroid function and the incidence of thyroid disease and discussed the scientific basis for establishing a tolerable upper intake level (UL) of iodine for Koreans. ULs are defined as "the highest level of daily nutrient intake that is likely to pose no risk of adverse effects to almost all individuals in the general population." Koreans consume excess iodine from seaweed, and iodine intake is strongly influenced by seaweed consumption. However, no dose-response data derived from subjects consuming excess iodine frequently but not continuously during a lifetime are available. Therefore, the Korean DRI committee set the iodine UL to reduce the risk of adverse health effects by excess iodine intake for Koreans with distinctive seaweed-eating habits.

Effects of chronic iodine excess on thyroid function and structure in autoimmune-prone NOD.H-2h4 mice / 中华内分泌代谢杂志

To explore the dose- and time- dependent relationship between the chronic iodine excess and thyroid structure, ultrastructure, and thyroid function in autoimmune-prone NOD. H-2h4 mice. Chronic iodine excess leads to iodine-induced goiter with an ultrastructure of follicle epithelial cells injury in a dose and time dependent way.

The effect of insulin-like growth factor-Ⅰ on thyroid morphologic change of mice with iodine deficiency and iodine excess / 中国地方病学杂志

Objective To study the expression level of thyroid insulin-like growth factor-Ⅰ (IGF-Ⅰ) in iodine deficiency and excess mice and the effect of thyroid gland IGF-Ⅰ in the thyroid morphological change. Methods Forty-eight Balb/c mice were chosen as studied objects,weighing about 16 g. They were divided into three groups: low iodine(LI,iodine content of 50 μg/kg in feed,drinking deironized water) group,normoi(NI,iodine content of 300 μg/kg in feed,drinking deironized water) group and high(HI,iodine content of 300 μg/kg in feed,iodoine of content 14 700 μg/kg in drinking) group,16 mice in each group. Mice were put to death after 12 weeks and taken out of their thyroid gland. The body weight,absolute and relative weights of thyroid gland were measured and the morphological change of thyroid gland were observed under microscope. The expression levels of thyroid gland IGF-Ⅰ mRNA and protein were detected by RT-PCR and immunohistochemistry,respectively. Results There were statistical significances between groups of thyroid absolute and relative weights(F = 315.881,405.921,all P < 0.01). LI group [(10.71±4.03) mg,(44.98±15.39)mg/100 g body weight]and HI group [(3.42±1.17)mg,(13.50± 3.89)mg/100 g body weight]had heavier thyroid absolute and relative weights than NI group[(2.11±0.53)mg,(8.35±1.98)mg/100 g body weight,all P < 0.01]. Under microscopy,the thyroid follicle capacity grew down and the follicle quantity grew up in LI group,the epithelium was stylolitic,the colloid diminished or absence in follicular cavity,while HI group presented colloid accumulation without follicular hyperplasia. The expression level of thyroid gland IGF-Ⅰ mRNA in LI group(1.03±0.32) was more than that in NI(0.65±0.19) and HI(0.59± 0.20) groups(F= 7.518,P< 0.01). In contrast to NI,there was no difference in the expression level of thyroid gland IGF-Ⅰ mRNA in HI group(P > 0.05). The brownish particles of LI group were more than NI and HI groups in the thyroid follicle epithelium by immunohistochemistry,while HI group was less than NI group. Conclusions The mice of iodine deficiency presented follicular hyperplasia goiter,the mice of iodine excess presented colloid accumulative goiter. The change of IGF-Ⅰ mRNA and protein expression may participate morphologleal change,indicating autocrine IGF-Ⅰ of thyroid gland may play an important role in regulating goiter formation.

Poly (I:C) promotes iodine excess-induced chronic lymphocytic thyroiditis in NOD mouse / 中国病理生理杂志

AIM: To investigate the effects of poly (I:C) as virus mimics on iodine excess-induced chronic lymphocytic thyroiditis in NOD mouse. METHODS: Female, 32 NOD mice were randomly divided into 4 groups: (1) control;(2) high iodine;(3) poly (I:C);(4) high iodine+poly (I:C). Nine weeks after administration, mice were sacrificed. The following parameters were determined: body weight, thyroid weight and anatomic form. Thyroid hormone (T_4) in serum was measured by radioimmunoassay, the thyroid morphology was observed through HE staining, apoptosis was detected by TUNEL, the mRNA expression levels of TRAIL, TRAIL-sR1, ICAM-1 and CXCL10 were determined by the method of real time RT-PCR. RESULTS: Compared to control group and poly (I:C) group, the thyroid absolute weight and relative weight in high iodine group were increased (P<0.01), the level of total T_4 in serum was decreased (P<0.05), inflammation and apoptosis were obviously observed, the mRNA expressions of TRAIL, TRAIL-sR1, CXCL10 and ICAM-1 were upregulated (P<0.05). Compared to high iodine group, thyroid absolute weight and relative weight in high iodine+poly (I:C) group were further increased, the level of total T_4 in serum was further decreased (P<0.05), the ratio of inflammatory degree Ⅳ increased to 50.0%, the numbers of apoptosis cells were further enhanced, the mRNA expressions of TRAIL, TRAIL-sR1, ICAM-1 and CXCL10 were further upregulated (P<0.05). Otherwise, the tendency of all parameters in poly (I:C) group was similar to that in control group (P>0.05). CONCLUSION: Poly (I:C) aggravates chronic lymphocytic thyroiditis induced by excess of iodine associated with increase in infiltration of lymphocytes and induction of apoptosis.

Exploratory study on the association between high iodine intake and lipid / 中华流行病学杂志

Objective To explore the association between excessive iodine intake and lipid disorder in human bodies. Methods Based on the NTTST sample survey on water iodine in Suining of Jiangsu province, this study involved 81 residents whose drinking water containing excessive iodine and 101 residents who drank water with normal iodine content. Blood samples were tested and compared on lipids (TG, TC, HDL-C, LDL-C, apoAl, apoB) between the two groups, after adjusting the influences of age and gender. The study also compared the abnormal rate of each lipid indicator between the two groups. Corresponding RR values and 95% confidence interval were calculated. Correlation between iodine content in drinking water and blood lipid was also studied. Results apoA1 in the group with excessive iodine intake was significantly lower than that in the normal iodine group, while there were no significant differences between the two groups in other lipid indicators. The abnormal rate of HDL-C of excess iodine group (16.88%) was significantly higher than the rate of normal iodine group (7.22%) while there were no significant differences between the two groups in other lipid indicators. Both apoAl and HDL-C in the excess iodine group had a negative correlation with water iodine, while the other indicators of two groups had no correlation with water iodine. Conclusion Drinking water with excess iodine might increase the risk of lipid disorder.

Sodium iodide symporter gene expression in thyroid of mice with different iodine intakes / 中华内分泌代谢杂志

Objective To investigate the sodium iodide symporter (NIS) gene expression during different iodine intakes and its function in thyroid autoregulation. Methods BabL/c mice were randomly divided into five groups according to their different iodine intake levels : low iodine (LI), normal iodine (NI), five-fold iodine (5HI) ,ten-fold iodine (10 HI) and fifty-fold iodine (50 HI). After three months and six months administration, they were sacrificed and thyroids were excised. The mRNA and protein expression level were determined by real time quantitative PCR and immunohistochemistry respectively. Iodine content in thyroid tissue was measured with spectrophotometry and thyroid hormone level was measured with radioimmunoassay. Results Compared with NI group, NIS mRNA and protein expression was greatly increased in LI groups. Immunohistochemistry analysis indicated that NIS was mostly located at the basolateral membrane of thyrocyte,suggesting the improved activity in transporting iodine. But when faced with long-term and severe iodine deficiency, the iodine content in thyroid was finally decreased ,and hormone level lowered. On the other hand, in HI groups NIS mRNA and protein expression was greatly down-regulated. There was a tendency of decreasing NIS gene expression level with increasing doses of iodine intakes. In addition, NIS protein was found mainly in intracellular vesicles, rather than at the cell membrane,suggesting the loss of its activity. The iodine content in thyroid tissue was only slightly increased and was not consistent with the iodine intake levels. Conclusion These findings indicate that NIS may be. regulated at transcription, translation and post-translation levels. This phenomenon constitutes a highly specialized intrinsic autoregulatory system that protects thyroid from high doses of iodine, but at the same time ensures adequate iodine uptake for hormone biosynthesis. NIS plays a critical role in thyroid autoregulation mechanism.

Pathological characteristics of thyroiditis in NOD mice induced by iodine excess and thyroglobulin immunization / 中华内分泌代谢杂志

Objective To observe the pathological characteristics of thyroiditis induced by iodine excess and thyroglobulin (Tg) immunization and to explore the mechanism of thyroiditis induced by iodine excess. Methods NOD mice were used for intaking 0.05% Nal water and(or) Tg immunization. Morphologic change in thyroid and apoptosis were observed. The levels of serum TT4, TSH, thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) were measured. Responding to Tg, lymphocytic proliferation of lymph node and spleen, interleukin-4(IL-4)and γ-interferon(IFN-γ) levels in culture medium of splenocytes were detected. Real-time PCR Was used to detect mRNA expressions of IL-4, IFN-γ, chemokine ligand 10 (CXCL10) and intercellular adhesion molecular-1(ICAM-1) in thyroid. Results Distended thyroid follicles,colloid accumulation, intense lymphocytic infiltration and disorganization were seen in thyroid of iodine excess group, along with increased apoptosis of thyroid cells(34.66～ 2.78 vs 5.11±0.62 ,P<0.01). The levels of TT4 were lowered while TSH raised ,but no production of thyroid-specific autoantibodies was revealed. Lymph node and spleen cells showed positive respornse under stimulation of Tg. The level of IFN-γ[(1. 272±0.049 vs 1. 139±0. 025)ng/L,P<0. 01] was raised in culture medium of splenocytes but not IL-4. The expression of IFN-γ, CXCLI0 and ICAM-1 mRNA were increased in thyroid. But in Tg group, some lymphocytes were scattered in thyroid, autoantibodies emerged ,and the level of IL-4 was increased in cuhure medium of splenocytes[(18. 508±0. 113 vs 13. 368±0. 016)ng/L, P<0. 01]. ledine excess combined with Tg enhanced these inflammatory reaction. Conclusion Iodine excess induced thyroiditis in NOD mice. The process seems to be Th1 response dominant organ-specific autoimmune diseases. Iodine excess and Tg immunizatiou play a synergistic role in inducing experimental autoimmune thyroiditis.