Adverse Effects on the Thyroid of Chinese Pregnant Women Exposed to Long-Term Iodine Excess: Optimal and Safe Tolerable Upper Intake Levels of Iodine.

Ensuring optimal iodine nutrition in pregnant women is a global public health concern. However, there is no direct data on safe tolerable upper intake levels (ULs) for pregnant women. A cross-sectional study was performed to determine the ULs of pregnant women. A total of 744 pregnant women were enrolled in this study. The median (IQR) urinary iodine concentration (UIC) in pregnant women was 150.2 (87.6, 268.0) µg/L, and the urinary iodine excretion (UIE) over 24 h was 204.2 (116.0, 387.0) µg/day. Compared with those with a UIE figure of between 150-250 µg/day, the reference group, the prevalence of thyroid dysfunction was 5.7 times higher (95%CI: 1.7, 19.2) in pregnant women with a UIE figure of between 450-550 µg/day, and 3.9 times higher (95%CI: 1.5, 10.3) in pregnant women with a UIE figure of ≥550 µg/day. Compared with an estimated iodine intake (EII) of between 100-200 µg/day, the reference group, the prevalence of thyroid dysfunction was 4.3 times higher (95%CI: 1.3, 14.4) in pregnant women with a UIE figure of between 500-600 µg/day, and 3.6 times higher (95%CI: 1.5, 8.9) in pregnant women with UIE of ≥600 µg/day. In general, our cross-sectional study found that excessive iodine intake during pregnancy appears to directly increase the risk of thyroid dysfunction. Avoiding chronic iodine intakes of 500 µg/day or higher or having a UIE figure of ≥450 µg/day is recommended for pregnant women in China.

Geographical influences on thyroid abnormalities in adult population from iodine-replete regions: a cross-sectional study.

The studies on the increasing incidence of thyroid abnormalities are scarce. The aim of this current study was to ascertain the effects of geographical region on thyroid abnormalities under the context of universal salt iodization (USI). We randomly selected 1255 participants residing in inland and 1248 in coast, with the determination of urinary iodine concentration (UIC) and functional and morphological abnormalities of thyroid gland. The median UIC was significantly higher for the inland participants (188.5 µg/L) than the coastal participants (128.5 µg/L; p < 0.001), indicating iodine sufficiency in both populations according to the recommended assessment criteria by the World Health Organization. However, the spectrum of thyroid abnormalities varied between regions, with hypothyroidism prevalent in inland and thyroid nodules in coast. The associations between region and thyroid abnormalities via binary logistic regression models showed that the coastal participants were at a higher risk of total thyroid abnormalities than those from the inland (OR 1.216, 95% CI 1.020-1.449), after the adjustment of ten confounders (demographical characteristics, smoking status, metabolism syndrome, and hyperuricemia). These results indicated that further investigations of the adverse effects of hypothyroidism and thyroid nodules on health burden is urgently needed to sustain USI program.

Urine iodine level and multiple risks are associated with thyroid structural abnormalities among adults in Heilongjiang Province, China.

BACKGROUND AND OBJECTIVES: The prevalence of adult thyroid structural abnormalities has increased significantly worldwide. However, no study has examined the thyroid structure and urine iodine levels of adults in Heilongjiang Province in the last decade. Therefore, this study aims to investigate the rate and risk factors of thyroid structural abnormalities among the residents of this province. METHODS AND STUDY DESIGN: A probability proportional sampling method was used, and a total of 3,645 individuals in Heilongjiang Province were included. The subjects was asked to complete a thyroid ultrasound and fill out a questionnaire. Furthermore, urine iodine levels and salt iodine content were determined, and multivariate logistic regression was used to identify the independent risk factors for thyroid diseases. RESULTS: The prevalence of thyroid structural abnormalities in Heilongjiang Province was 56.0%. Univariate analysis showed that there were significant differences between the structural abnormalities group and the normal thyroid group in terms of sex, age, body mass index, hypertension, diabetes, smoking, alcohol consumption, frequency of seafood consumption and pickled food consumption, employment status, and urine iodine level (p<0.05). Multivariate analysis showed that the following were independent risk factors of thyroid disease: female, increased age, hypertension, diabetes, cigarette smoking frequent seafood consumption, employment, and urine iodine levels. CONCLUSIONS: The prevalence of thyroid structural abnormalities in adults in Heilongjiang Province was relatively high. Therefore, to help prevent the occurrence of thyroid disease in adults in Heilongjiang Province, the risk factors of thyroid structural abnormalities should be better understood.

Urinary Iodine Concentration in a Cohort of Adult Outpatients with Thyroid Diseases in Liguria 14 Years after the Law on Salt Iodization.

Italy is considered a mildly iodine-deficient country. The aim of this study was to evaluate the iodine status of a cohort of adults living in Liguria after the 2005 salt iodization program. We searched all medical records of patients examined in two endocrine outpatient clinics in Genoa and Savona for data on urinary iodine. Subjects were under evaluation for thyroid diseases. Information on the type of salt used was found in few clinical records. Iodized salt use was reported in 29%, 20%, and 13% of records of people living in Genoa districts, the Savona district and nearby districts, respectively. The average urinary iodine concentration was 112.9 ± 62.3 µg/L (n = 415, median 101.0 µg/L). Non-significant differences (P > 0.05) were found between subjects with (median 103.5 µg/L) and without (median 97.5 µg/L) a thyroid gland, between the periods 2009-2013 (median 105.0 µg/L) and 2014-2018 (median 97.5 µg/L), and between Genoa (median 94.0 µg/L), Savona (median 105.0 µg/L) and the other districts (median 114.5 µg/L). No correlation with age, body mass index, creatinine, free thyroxine, thyroglobulin, levo-thyroxine dosage, or thyroid volume was observed. These data suggest a borderline status of iodine sufficiency in this cohort.

Urinary Iodine Concentration and Mortality Among U.S. Adults.

BACKGROUND: Iodine deficiency has long been recognized as an important public health problem. Global approaches such as salt iodization that aim to overcome iodine deficiency have been successful. Meanwhile, they have led to excessive iodine consumption in some populations, thereby increasing the risks of iodine-induced thyroid dysfunction, as well as the comorbidities and mortality associated with hypothyroidism and hyperthyroidism. This study aimed to elucidate whether iodine intake is associated with mortality among U.S. adults. METHODS: This was an observational study to estimate mortality risks according to urinary iodine concentration (UIC) utilizing a nationally representative sample of 12,264 adults aged 20-80 years enrolled in the National Health and Nutrition Examination Survey (NHANES) III. Crude and multivariable Cox proportional hazards regression models were employed to investigate the association between UIC (<50, 50-99, 100-299, 300-399, and ≥400 µg/L) and mortalities (all-cause, cardiovascular, and cancer). In sensitivity analyses, the study adjusted for total sodium intake and fat/calorie ratio in addition to other potential confounders. Stratum-specific analyses were also conducted to estimate the effects of UIC on mortality according to age, sex, race/ethnicity, and estimated glomerular filtration rate category. RESULTS: Over a median follow-up of 19.2 years, there were 3159 deaths from all causes. Participants with excess iodine exposure (UIC ≥400 µg/L) were at higher risk for all-cause mortality compared to those with adequate iodine nutrition (hazard ratio = 1.19 [confidence interval 1.04-1.37]). Elevated hazard ratios of cardiovascular and cancer mortality were also found, but the confidence interval of the effect estimates included the null value for both outcomes. Low UIC was not associated with increased mortality. Restricted cubic spline models showed similar results for all outcomes. The results did not change substantially after adjusting for total sodium intake and fat/calorie ratio. None of the potential interactions were statistically significant on a multiplicative scale. CONCLUSION: Higher all-cause mortality among those with excess iodine intake compared to individuals with adequate iodine intake highlights the importance of monitoring population iodine status. Further studies with longitudinal measures of iodine status are needed to validate these results and to assess the potential risks excess iodine intake may have on long-term health outcomes.

Comprehensive Metabolic Profiling Reveals a Lipid-Rich Fingerprint of Free Thyroxine Far Beyond Classic Parameters.

Objective: Thyroid hormones are ubiquitously involved in human metabolism. However, the precise molecular patterns associated with alterations in thyroid hormones levels remain to be explored in detail. A number of recent studies took great advantage of metabolomics profiling to outline the metabolic actions of thyroid hormones in humans. Methods: Among 952 participants in the Study of Health in Pomerania, data on serum free thyroxine (FT4) and thyrotropin and comprehensive nontargeted metabolomics data from plasma and urine samples were available. Linear regression analyses were performed to assess the association between FT4 or thyrotropin and metabolite levels. Results and Conclusion: After accounting for major confounders, 106 of 613 plasma metabolites were significantly associated with FT4. The associations in urine were minor (12 of 587). Most of the plasma metabolites consisted of lipid species, and subsequent analysis of highly resolved lipoprotein subclasses measured by proton nuclear magnetic resonance spectroscopy revealed a consistent decrease in several of these species (e.g., phospholipids) and large low-density lipoprotein and small high-density lipoprotein particles. The latter was unique to men. Several polyunsaturated and saturated fatty acids displayed an association with FT4 in women only. A random forest-based variable selection approach using phenotypic characteristics revealed higher alcohol intake in men and an adverse thyroid state and menopause in women as the putative mediating factors. In general, our observations have confirmed the lipolytic and lipogenic effect of thyroid hormones even in the physiological range and revealed different phenotypic characteristics (e.g., lifestyle differences) as possible confounders for sex-specific findings.

The application of serum iodine in assessing individual iodine status.

CONTEXT: The prevalence of thyroid disease in China is on the rise, and this could be partly associated with excessive iodine intake in some individuals; therefore, increased attention is being paid to individual iodine status. However, current indices are not appropriate for evaluating individual iodine status. OBJECTIVE: To evaluate the association between serum iodine and urinary iodine (UI), as well as thyroid diseases, and provide an excellent base for future individual iodine status assessment. DESIGN, SUBJECTS AND MEASUREMENTS: A total of 902 adults were enrolled in this study including 325, 286 and 291 subjects from regions in China where iodine is adequate, sufficient and in excess, respectively. Serum iodine, UI and thyroid function were assessed, and ultrasonography performed in all subjects. RESULTS: The median serum iodine values of adults with subclinical hypothyroidism, high serum autoantibody and thyroid nodules were significantly higher than those of euthyroid adults (P<0.05). A serum iodine level higher than 100 µg/L was considered as a risk factor for thyroid diseases. Serum iodine had strong nonlinear correlations with UI and thyroid function. When thyroid function was taken as a gold standard, the area under the receiver operating characteristic (ROC) curve for serum iodine was 0.752 and UI was 0.507 for subjects with lower serum iodine and UI levels. The area for serum iodine was 0.773 and UI was 0.638 for subjects with higher serum iodine and UI levels. The areas under these curves were significantly different (P<0.001). CONCLUSION: In adults, serum iodine had a strong nonlinear correlation with UI and a high level of serum iodine was a risk factor for thyroid diseases.

Urinary iodine concentration (UIC) could be a promising biomarker for predicting goiter among school-age children: A systematic review and meta-analysis.

OBJECTIVES: To evaluate whether urinary iodine concentration (UIC) can predict goiter among school-age children, and to assess the association between UIC and goiter prevalence. METHODS: We searched the MEDLINE, EMBASE, Cochrane Library (Cochrane Database of Systematic Reviews), Web of Science, CNKI, VIP, and Wan Fang databases for relevant reports in both English and Chinese up to August 25, 2016. The mean differences (MD) and 95% confidence intervals (CI) were calculated for the UIC and goiter prevalence assessments. Pooled odds ratios and 95% CIs were used to compare the prevalences of goiter in the different UIC groups. RESULTS: We identified 11 case-control studies, and found that children with goiter had lower UIC values, compared to children without goiter (MD: -1.82, 95% CI: -3.24, -0.40, p < 0.05). An increased risk of goiter was associated with UIC values of < 20 µg/L or > 200 µg/L. CONCLUSION: The results of our meta-analysis suggest that lower UIC values were associated with an increased risk of goiter, and that iodine deficiency may lead to an increased risk of goiter. Furthermore, we observed U-shaped relationships between UIC and the prevalence of goiter, which suggests that both severe iodine deficiency and excessive iodine intake may lead to increased risks of goiter.

Urinary iodine and thyroid determinants in pregnancy: a follow up study in Sri Lanka.

BACKGROUND: Iodine deficiency and thyroid dysfunction during pregnancy is associated with number of adverse outcomes that includes mental and physical disabilities creating a huge human and economic burden in later life. Several indicators are used to assess the iodine status of a population: thyroid size by palpation and/or by ultrasonography, urinary iodine excretion and the blood thyroid hormone profile. METHODS: This prospective study was designed to assess the iodine nutrition during the course of pregnancy with reference to urine iodine concentration (UIC) and thyroid determinants among 425 pregnant women from Galle district, Sri Lanka. UIC was estimated in all three trimesters and thyroid functions were assessed in first and third trimesters. RESULTS: Median (inter-quartile range IQR) UIC was 170.9 (100.0-261.10) µg/L, 123.80 (73.50-189.50) µg/L and 105.95 (67.00-153.50) µg/L in the first, second and third trimesters respectively (p < 0.001). Median thyroid stimulating hormone (TSH) level in the first trimester was 1.30 (0.80-1.80) µIU/mL. This value significantly increased (p < 0.001) to 1.60 (1.20-2.10) µIU/mL at the 3rd trimester even though it was maintained within the reference range (0.3 - 5.2 µIU/mL). In the assessment of thyroid gland, 67 (16.0 %) women had palpable or visible goitres and 55 (13.1 %) had a goitre that was palpable but not visible. The median thyroid volume of the sample was 5.16 mL (4.30; 6.10 mL) as measured by ultra sound (US) scanning. In multiple regression analysis after controlling for other independent variables (anthropometric, demographic and biochemical parameters); initial body mass index (BMI), goitre size, thyroid volume and parity had significant correlations with the third trimester urinary iodine levels. The thyroid volume accounted for 4.5 % of the urinary iodine variation. CONCLUSIONS: Even though iodine status was progressively worsening with the advancement of pregnancy and iodized salt consumption has not met with the increasing demand for iodine, it was not reflected in the serum TSH level. Therefore, it is worthwhile to assess the long term effects of rising TSH levels and inadequate iodine nutrition during pregnancy on the offspring to prevent even mild iodine deficiency.

Iodine Status and Prevalence of Thyroid Disorders After Introduction of Mandatory Universal Salt Iodization for 16 Years in China: A Cross-Sectional Study in 10 Cities.

BACKGROUND: The goal of eliminating iodine deficiency worldwide was successfully achieved in China after the implementation of a mandatory universal salt iodization program for the last 16 years. Thus, China has been assessed as a country with more than adequate iodine levels. This survey aimed to investigate the current iodine status in China and the effects of an increased iodine intake on the spectrum and prevalence of thyroid disorders. METHODS: A total of 15,008 adult subjects from 10 cities in eastern and central China were investigated. Serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb), and urine iodine concentration (UIC) were measured, and an ultrasonography of the thyroid was performed in all subjects. Free thyroxine (fT4) and free triiodothyronine (fT3) levels were only measured if the serum TSH was outside the normal range. RESULTS: The median UIC values were 197 µg/L in school-age children (SAC) and 205 µg/L in a cohort population. Six cities were classified as regions with adequate iodine intake (AII), and four cities as regions with more than adequate iodine intake (MTAII), according to median SAC UIC. The prevalence of clinical hypothyroidism, subclinical hypothyroidism, and positive thyroid antibodies was significantly higher in MTAII cities than it was in AII cities. Moreover, the prevalence of clinical hyperthyroidism (1.1% vs. 0.8%, p = 0.033) and Graves' disease (0.8% vs. 0.5%, p = 0.019) also significantly increased in MTAII cities. Compared with a five-year prospective study conducted in 1999, the prevalence of goiter significantly decreased (2.9% vs. 5.02%, p = 0.001), but there was a significant increase in thyroid nodules (12.8% vs. 2.78%, p = 0.001). The prevalence of subclinical hypothyroidism (16.7% vs. 3.22%), positive TPOAb (11.5% vs. 9.81%), and positive TgAb (12.6% vs. 9.09%) significantly increased, while no changes were seen in clinical hyperthyroidism, subclinical hyperthyroidism, or Graves' disease. CONCLUSION: The goal of eliminating iodine deficiency has been successfully achieved in China. However, the prevalence and spectrum of thyroid disorders has increased, reflecting possible adverse effects of increased iodine intake.

Incidence of thyroid diseases in Zhejiang Province, China, after 15 years of salt iodization.

Thyroid diseases(TD) can be induced by either deficient or excessive iodine intake. Universal Salt Iodization(USI) program has been implemented in China since 1995, to prevent iodine deficiency disorders (IDD). To evaluate the current conditions of TD and the role of USI, a multi-stage stratified random sampling scheme was used to perform a cross-sectional survey on the incidence of TD among participants in 6600 households in Zhejiang Province, a coastal area in China. Iodine nutrition status of the population was assessed by dietary iodine intake recall and urinary iodine concentration (UIC) of the participants, and TD were diagnosed by thyroid ultrasonography for 15122 participants and for 5873 participants by serum criteria for thyroid function(fT3, fT4, TSH, TRAb, TgAb, TPOAb; see Introduction for abbreviations). The median UIC of the surveyed population was 163µg iodine/L. From the participants 23.2% had UIC<100µg/L which is moderately iodine-deficient according to WHO classification. Diffuse goiter was present in 2.3% of the population and thyroid nodule in 20.9%. The incidence of hyperthyroidism, subclinical hyperthyroidism, hypothyroidism, subclinical hypothyroidism, Graves' disease and chronic lymphocytic thyroiditis was 0.5%, 0.6%, 0.6%, 7.8%, 0.2% and 0.3%, respectively. The proportion of several TD for participants with non-iodized salt intake was higher than that for participants with iodized salt intake.

Iodine nutrition status and thyroid disorders: a cross-sectional study from the Xinjiang Autonomous Region of China.

BACKGROUND/OBJECTIVES: Iodine nutritional status and its influence on thyroid function have been thoroughly investigated in many places in China, but little is known about Xinjiang province, where multiple minorities are living in a special geographical location and have different lifestyles compared with people from other parts of China. The aim of this study was to evaluate iodine status and thyroid disorders in two major ethnic groups living in the Xinjiang region of China. SUBJECTS/METHODS: A total of 2253 residents over the age of 18 years who had lived in Xinjiang for more than 3 years were enrolled. Urinary iodine concentration (UIC), serum thyroid hormone concentrations and thyroid autoantibodies were measured, and thyroid ultrasonography was performed. RESULTS: The median UIC was 130.7 µg/l in adults. Among the subjects, those with deficient UIC levels were 34.4%. The prevalence of overt hyper- and hypothyroidism in the iodine-deficient group was higher than in the iodine-sufficient group (1.3% vs 0%, χ2=3.891, P=0.049; 4.8% vs 2.8%, χ2=8.715, P=0.003, respectively), and subclinical hypothyroidism was more frequent in the iodine-deficient group than in the iodine-excess group (19.6% vs 12.5%, χ2=4.529, P=0.033). CONCLUSIONS: One-third of the population is still iodine deficient in Xinjiang. Uyghur females are more susceptible to hypothyroidism and thyroid autoimmune diseases. Thyroid disorders, especially hyper/hypothyroidism and subclinical hypothyroidism, are more likely to be prevalent in an iodine-deficient population.

Iodine status from childhood to adulthood in females living in North-East Italy: Iodine deficiency is still an issue.

PURPOSE: This survey aimed to assess iodine status in a female population at different ages, also investigating their eating habits. METHODS: We measured urinary iodine concentrations (UIC) in: 634 females at puberty and 361 fertile women in 246 of whom were considered also their children (134 daughters and 120 sons). All subjects completed a food frequency questionnaire. RESULTS: Median UIC decreased from childhood to adulthood (median UIC 107, 77 and 55 µg/l in the young girls, females at puberty and fertile women, respectively). Though using iodized salt improved iodine status in all groups, a significantly higher UIC was only noted in females at puberty. Milk consumption significantly increased UIC at all ages. In mother-child (both daughters and sons) pairs, the children's median UIC was nearly twice as high as their mothers' (UIC 115 vs. 57 µg/l). Milk consumption varied significantly: 56% of the mothers and 76% of their children drank milk regularly. The children (both daughters and sons) and mothers who drank milk had UIC ≥100 µg/l in 59 and 34% of cases, respectively, among the pairs who did not drink milk, 44% of the children and 19% of the mothers had UIC ≥100 µg/l. On statistical regression, 3.6% of the variability in the children's UIC depended on that of their mothers. CONCLUSIONS: Dietary iodine status declines from childhood to adulthood in females due to different eating habits. A mild iodine deficiency emerged in women of child-bearing age that could have consequences during pregnancy and lactation.

The relationship between iodine nutrition and thyroid disease in lactating women with different iodine intakes.

Areas with low, adequate and excessive I content in water co-exist in China. Limited data are currently available on I nutrition and thyroid disease in lactating women and their breast-fed infants with different I intakes. This study aimed to evaluate I nutrition in both lactating women and their infants and the prevalence of thyroid disease in areas with different levels of I in water. From January to June 2014, a total of 343 healthy lactating women (excluding those taking anti-thyroid drugs or I supplements within a year of the study, consuming seafood at the time of the study or those diagnosed with congenital thyroid disease) from Beihai in Guangxi province and Jiajiazhuang, Yangcheng, Jicun and Pingyao townships in Shanxi province were selected. Compared with the I-sufficient group, median urinary I concentrations in both lactating women and infants as well as breast milk I levels were significantly lower in the I-deficient group (P<0·001). The prevalence of thyroid disease in lactating women, particularly subclinical hypothyroidism, was higher in the I-excess group than in the I-sufficient group (P<0·05). In areas with excessive water I content, high thyroid peroxidase antibody and high thyroglobulin levels were risk factors for abnormal thyroid-stimulating hormone levels. Our data collectively suggest that excessive I intake potentially causes subclinical hypothyroidism in lactating women. Moreover, enhanced monitoring of I status is important to avoid adverse effects of I deficiency or excess, particularly in susceptible populations such as pregnant or lactating women and infants.

Potentiometric measurement of urinary iodine concentration in patients with thyroid diseases with and without previous exposure to non-radioactive iodine.

BACKGROUND: Extensive application of measurement of urinary iodine concentration (UIC) in several benign and malignant thyroid diseases could profit by the availability of rapid and inexpensive measuring techniques. Aim of this study was to apply a simple and inexpensive commercially available potentiometric method for the quantification of UIC based on iodine-specific ion-selective electrodes (ISE) in patients with thyroid diseases. METHODS: This retrospective study included patients with differentiated thyroid cancer (n=286) and patients with hyperthyroidism of different etiologies (n=203). Within the whole sample (n=489) 20 patients had previously (1 week-6 months) been exposed to iodine overload, either from contrast media (n=8) or amiodarone (n=12). RESULTS: In patients not exposed to iodine, the histogram showed that the distribution of UIC violated normality. The peak of the curve occurred between 5.0 µmol/L and 6.0 µmol/L. Variability was sizeable (percent coefficient of variation, %CV: 66%, 95% confidence interval: 1.48-18.72 µmol/L). The group of exposed patients could be easily distinguished from not exposed patients (median UIC: 47.5 µmol/L vs. 5.42 µmol/L). UIC was significantly correlated to urinary creatinine concentration, but normalization to urinary creatinine increased the inter-subject variability of UIC (%CV=96% vs. 66%). In test-retest studies (n=25) the intra-class correlation coefficient was 0.73 for UIC, 0.82 for creatinine and 0.64 for the UIC: creatinine ratio. CONCLUSIONS: Iodine-specific ISE-based potentiometric methods can be successfully applied as an alternative to existing methods in patients with thyroid diseases. The promising characteristics of the method need to be confirmed in future larger prospective studies.

Iodine nutritional status after the implementation of the new iodized salt concentration standard in Zhejiang Province, China.

BACKGROUND: Iodine deficiencies were prevalent in China until the introduction of universal salt iodization (USI) in 1995. In 2012, the standard salt iodine concentration was adjusted to 20-30 mg/kg. The success of USI for the control of iodine deficiency disorders requires monitoring its effect at a population level. METHODS: Two cross sectional surveys of a representative sample of children aged 8-10 years in Zhejiang Province were carried out in 2011 and 2013. Data on participants' socio-demographic characteristics were collected from the children using a structured questionnaire. Spot urine samples were collected and delivered to local Center for Disease Control and Prevention laboratory for measuring urinary iodine concentration. In 2011, out of 420 selected children aged 8-10 years, 391 were recorded and provided urine samples. In 2013, out of 1560 selected children aged 8-10 years, 1556 were recorded and provided urine samples. RESULTS: The median urinary iodine concentration of subjects in the 2013 survey was 174.3 µg/L, significantly lower than that of 2011(p = 0.000). The median urinary iodine concentration of subjects living in urban and rural areas in the 2013 survey was 169.0 µg/L, and 186.1 µg/L respectively, significantly lower than that of 2011 only for subjects living in urban areas (p = 0.000). There were no significant differences for subjects living in rural areas in the survey in 2011 and in 2013 (p = 0.086). CONCLUSIONS: At the time the new local iodization policy put forward, iodine nutrition was generally adequate in both urban and rural areas, suggesting that the new policy for adjusting the standard salt iodine concentration is effective. Our data also indicate that the reason people living in urban areas had a lower urinary iodine concentration than people in rural areas may be due to their preference for using non-iodized salt in the last 2 or 3 years. Maintaining USI at an appropriate level is an important part of preventing iodine deficiency disorders and should always be based on regular monitoring and comparison of urinary iodine concentration by province.

Iodine status in Korean preschool children as determined by urinary iodine excretion.

PURPOSE: Iodine is a trace element of thyroid hormones. Excessive or insufficient iodine intake is associated with various thyroid diseases. Urinary iodine (UI) is a sensitive indicator and a recommended barometer of population iodine intake. In Korea, there has been no available data regarding iodine intake in preschool children. We investigated the iodine intake status of Korean preschool children through examination of their UI. METHODS: This cross-sectional study was performed in 611 healthy preschool children (302 from Seoul and 309 from Masan), aged from 2 to 7 in 2010. UI concentration was measured by inductively coupled plasma-mass spectrometry. RESULTS: The median UI concentration was 438.8 µg/L. Insufficient iodine intakes (<100 µg/L) were seen in 24 children (3.9%), and excessive iodine ingestion (>300 µg/L) was found in 406 children (66.4%). There were no significant differences in UI between different sexes and ages. Additionally, the median UI concentration was higher in children from Seoul (512.2 µg/L) than that in children from Masan (362.4 µg/L, P < 0.001). CONCLUSION: About two-thirds of Korean preschool children were in the state of excessive iodine intake, and 3.9% of children showed insufficient iodine intake. Preventive measures and follow-up for iodine intake in preschool children are needed.

Correlação entre níveis de iodo na urina e alterações anatomopatológicas em tireoide / Correlation between iodine urinary levels and pathological changes in thyroid glands

OBJETIVOS: Determinar o aporte nutricional de iodo na população estudada e correlacionar os níveis de iodo encontrados em amostras casuais de urina (iodúria) com alterações anatomopatológicas observadas nas tireoides dessa população. MATERIAIS E MÉTODOS: Determinou-se a iodúria em 30 amostras casuais de urina e realizou-se o estudo anatomopatológico de 55 tireoides colhidas de cadáveres que deram entrada no Departamento Médico Legal de Vitória, Espírito Santo, Brasil, no período de maio a agosto de 2011. RESULTADOS: Em 29 amostras de urina (96,7%) encontrou-se iodúria acima do limite máximo preconizado pela Organização Mundial da Saúde (OMS) de 300 µg/L. Em 14 tireoides (25,5%) foi identificada a presença de quadros histológicos compatíveis com tireoidite. Níveis mais elevados de iodo na urina foram observados no sexo feminino e nos casos de tireoides com presença de achados inflamatórios (tireoidites). CONCLUSÕES: Podemos concluir que na população estudada houve um excesso de iodo em seu aporte nutricional e uma maior incidência de quadros inflamatórios tireoidianos.

OBJECTIVES: To determine iodine nutrition in the population and to correlate levels of iodine found in random samples of urine with pathological changes observed in thyroids collected in this population. MATERIALS AND METHODS: Urinary iodine was determined in 30 random samples of urine and the pathological study was carried out in 55 thyroid glands from corpses received by the Department of Forensic Medicine of Vitória, Espírito Santo, Brazil from May to August 2011. RESULTS: In 29 urine samples (96.7%) urinary iodine was above the maximum limit recommended by the World Health Organization (WHO), of 300 mg/L. Fourteen thyroids (25.5%) showed the presence of histological changes compatible with thyroiditis. Higher levels of iodine in urine were observed in females and in of thyroid that showed inflammation (thyroiditis). CONCLUSIONS: We conclude that, in this population, there is excess iodine intake, and greater incidence of inflammatory thyroid disease.

Iodine deficiency and excess in children: worldwide status in 2013.

OBJECTIVE: Assessing iodine nutrition at the population level is usually done by measuring the urinary iodine concentration (UIC) and, in some countries, by estimating household coverage of adequately iodized salt (HHIS). Using these indicators, the objective of this review is to assess global and national iodine status in 2013. METHODS: The most recent data on HHIS were obtained from the United Nations Children's Fund. The most recent data on UICs were obtained from the International Council for the Control of Iodine Deficiency Disorders Global Network and the World Health Organization (WHO). Median UIC was used to classify national iodine status based on the current WHO classification system, with the following modification: the "adequate (100 to 199 µg/L)" and "more than adequate (200 to 299 µg/L)" categories of median UIC in school-aged children were combined into a single category of "adequate" iodine intake (100 to 299 µg/L). RESULTS: Over the past decade, the number of countries that are iodine deficient has fallen from 54 to 30. The number iodine-sufficient countries has increased from 67 to 112, while the number with excessive iodine intake has increased from 5 to 10. In most countries with excess intake, this is due to overiodization of salt and/or poor monitoring of salt iodization. Out of 128 countries with HHIS data, at least 90% of households in 37 countries consume adequately iodized salt, but in 39 countries, coverage rates are below 50%. Overall, about 70% of households worldwide have access to iodized salt. CONCLUSION: There has been substantial recent progress in the global effort to control iodine deficiency. However, iodized salt programs need to be carefully monitored to ensure adequate iodine intake while avoiding iodine excess.

Metals in blood and urine, and thyroid function among adults in the United States 2007-2008.

The thyroid is integral to regulation of development and metabolism. Certain metals have been shown to affect thyroid function in occupationally exposed persons, but few studies have been conducted in the general population. This study evaluates the association between biomarkers of metal exposure and thyroid hormones in the US population. Analyses included adults participating in the 2007-2008 National Health and Nutrition Examination Survey, with no history of thyroid disease or use of thyroid medications, and with data on metals in blood (lead, cadmium and mercury) and urine (lead, cadmium, mercury, barium, cobalt, cesium, molybdenum, antimony, thallium, tungsten and uranium), and thyroid hormones (TSH, free and total T3 and T4) in serum (N=1587). Multivariate linear regression was used to model the association between thyroid hormone levels, and metals in either urine (creatinine-adjusted) or blood. Metal concentrations were considered as both continuous and categorical variables. Models were adjusted for: age, sex, race, BMI, serum lipids, serum cotinine, pregnancy and menopausal status, and use of selected medications. Few participants (<5%) had free T3, free T4, or TSH levels outside the reference range. However, 9.2% (SE=1.2%) had low T3 and 9.4% (SE=1.1%) had low T4. Metals were detected in nearly all blood and urine samples, with the highest levels seen for urinary molybdenum (median 42.5µg/L). When including all blood metals, mercury was associated with decreases in T3 and T4, while cadmium was associated with decreased TSH. Urinary cadmium was associated with increases in both T3 and T4 (models including all metals measured in urine). Urinary thallium and barium were associated with decreased T4 (both) and T3 (barium). For TSH, cesium was associated with decreased, and tungsten with increased levels. Given the high prevalence of exposure to metals, associations of the size reported here could indicate an appreciable contribution of metals exposure to the prevalence of thyroid disorders. These findings indicate the importance of further research to further examine these relationships.