Iodine Nutrition In Population Research Articles

Salivary iodide status as a measure of whole body iodine homoeostasis?

Iodine is a trace element required to produce the thyroid hormones, which are critical for development, growth and metabolism. To ensure appropriate population iodine nutrition, convenient and accurate methods of monitoring are necessary. Current methods for determining iodine status either involve a significant participant burden or are subject to considerable intra-individual variation. The continuous secretion of iodide in saliva potentially permits its use as a convenient, non-invasive assessment of status in populations. To assess its likely effectiveness, we reviewed studies analysing the association between salivary iodide concentration (SIC) and dietary iodine intake, urinary iodide concentration (UIC) and/or 24-h urinary iodide excretion (UIE). Eight studies conducted in different countries met the inclusion criteria, including data for 921 subjects: 702 healthy participants and 219 with health conditions. SIC correlated positively with UIC and/or UIE in four studies, with the strength of relationship ranging from r = 0·19 to r = 0·90 depending on sampling protocol, age, and if salivary values were corrected for protein concentration. Additionally, SIC positively correlated with dietary intake, being strongest when saliva was collected after dinner. SIC varied with external factors, including thyroid function, use of some medications, smoking and overall health status. Evidence provided here supports the use of SIC as a viable, low-burden method for determining iodine status in populations. However, small sample sizes and high variability indicates the need for more extensive analyses across age groups, ethnicities, disease states and dietary groups to clarify the relative accuracy and reliability in each case and standardise procedure.

Metabolites in Urine that Interfere with the Sandell-Kolthoff Assay for Urinary Iodine.

The Sandell-Kolthoff (SK) assay is the main analytical method used to monitor population iodine nutrition in low- and middle-income countries. This assay can distinguish between populations that are iodine-deficient (median urinary iodine levels below 100 ppb), iodine-sufficient (median urinary iodine levels between 100 and 300 ppb), and iodine- excessive(median urinary iodine levels above 300 ppb). However, the analysis of urine samples with the SK reaction is technically challenging, partly because urine samples must be rigorously pretreated to remove interferents. In the literature, the only urinary metabolite that has been identified as an interferent is ascorbic acid. In this study, we used the microplate SK method to screen thirty-three of the major organic metabolites present in urine. We identified four previously unknown interferents: citric acid, cysteine, glycolic acid and urobilin. For each interferent, we investigated the following factors: (1) nature of interference-positive or negative, (2) threshold concentration for interference, and (3) possible mechanisms of interference. While this paper does not attempt to provide an exhaustive list of all interferents, knowledge of the main interferents allows for targeted removal.

What Iodine Intervention Measures Should Be Taken in Different Water Iodine Areas? Evidence from a Cross-sectional Chinese Survey.

The aim of this study was to assess the population's iodine nutrition and thyroid diseases in different water iodine areas and to offer suggestions to the governments of different countries to adjust the present policy in different water iodine areas. A cross-sectional survey was conducted in different water iodine areas in China. Urinary iodine, water iodine, salt iodine and thyroid function were determined. The thyroid volumes and nodules were measured by ultrasound. Upon categorization by water iodine level for the 10.0 ~ 39.9μg/L, 40.0 ~ 100.0μg/L and 100.1 ~ 150.0μg/L areas, in adults, the prevalence of subclinical hypothyroidism was 9.28%, 5.35% and 11.07%, and the median urinary iodine (MUI) was 153.7μg/L, 189.8μg/L and 317.0μg/L; in children of the three areas, the prevalence of goitre was 3.83%, 4.47% and 16.02%, and the MUI was 164.1μg/L, 221.0μg/L and 323.3μg/L; in pregnant women of those areas, the MUI was 148.6μg/L, 176.9μg/L and 324.9μg/L. Logistic regression results indicated that low iodine intake was a risk factor for developing hypothyroxinaemia in pregnant women. The iodine status of pregnant women is insufficient in areas with a median water iodine level of 10.0 ~ 39.9μg/L. Low iodine intake increases the risk of developing hypothyroxinaemia in pregnant women. The iodine status of adults and children is excessive, and the iodine status of pregnant women is above the requirements in areas with a median water iodine concentration of 100.1 ~ 150.0μg/L. Iodized salt, especially for pregnant women, should be supplied in areas with a median water iodine concentration of 10.0 ~ 39.9μg/L to improve the iodine status of pregnant women. Supplying non-iodized salt is not enough to protect local residents from the harm from excess iodine in areas with a median water iodine concentration above 100.0μg/L.

A Stratified Cross-Sectional Cluster Model Survey of Iodine Nutrition in Armenia After A Decade of Universal Salt Iodization

Objective: Iodine is a necessary nutrient for the synthesis of thyroid hormones and essential in human development. Being naturally deficient in iodine, Armenia launched a national universal salt iodization (USI) strategy in 2004. Although high rates of goiter continued to be reported, iodine status has not been studied since 2005. Therefore, this study sought to assess the current situation of population iodine nutrition in Armenia. Methods: We used a selective cross-sectional model to recruit three groups: school-age children (SAC), pregnant women (PW), and nonpregnant women of reproductive age (WRA) from each province. We collected casual urine and table salt samples from each participant, which were analyzed for iodine concentration. A repeat urine sample was collected in a subset of participants to adjust the results for within-person variation in iodine concentration. Group-wise urinary iodine concentrations (UICs) were compared with international reference criteria for iodine status. Results: Urine samples were collected from 1,125 participants from 13 different towns in Armenia; a total of 1,078 participants were included in the final analysis: 361 SAC (mean age, 10.5 years, 46.6% female), 356 PW (mean age, 26.1 years), and 361 WRA (mean age, 35.5 years). Population and geographically weighted median UIC were: SAC, 242 μg/L ([25th percentile] 203 to [75th percentile] 289 μg/L); PW, 226 μg/L (209 to 247 μg/L); WRA, 311 μg/L (244 to 371 μg/L). A total of 1,041 table salt samples were sufficient for laboratory analysis: 973 (93.4%) of the salt iodine measurements were within the national standard range of 40 ± 15 mg/kg. Conclusion: The results of household salt sampling indicated a successful USI strategy. While the present study did not achieve a truly representative sample of Armenia's population, the UIC results support the conclusion that iodine deficiency has not recurred and is not an underlying factor for any remaining high goiter prevalence in Armenia. Abbreviations: PW = pregnant women; SAC = school-age children; SI = salt iodine; UIC = urinary iodine concentration; USI = universal salt iodization; WHO = World Health Organization; WRA = women of reproductive age.

The results of neonatal TSH screening do not agree with indicators of the optimal iodine status of pregnant women in the Republic of Georgia

Background. Georgia historically was a country with moderate to severe iodine deficiency and high prevalence of endemic goiter. A representative countrywide iodine survey conducted in Georgia in 2017 confirmed optimal iodine nutrition of the population with median UIC 298 mcg/L in SAC and 211 mcg/L in PW.
 Aim. The aim of this study was to assess status of iodine nutrition of population in Georgia.
 Methods. The assesement based on the proportion of neonatal Thyroid-Stimulating Hormone (TSH) levels >5mIU/L from 2009 to 2015 and compare these data with the results of direct assessment of iodine status made during the 2017 national survey.
 Results. From 2009 to 2015 the proportion of newborns with TSH >20 mIU/L decreased threefold: from 0.45 to 0.15%. This trend was observed in all regions of the country with significant difference between the capital city and Western in Eastern parts of the country. There has been also significant reduction of the prevalence of TSH >5 mIU/L in Georgia from 4.46% in 2009 to 3.5% in 2015. However, only in Tbilisi the frequency of elevated TSH was below 3% – the cutoff level for adequate iodine nutrition. In other regions (Western and Eastern Georgia) prevalence of TSH >5 mIU/L was 3.8% and 4.4% respectively that could be falsely interpreted as mild iodine deficiency.
 Conclusions. Although neonatal TSH is useful to detect moderate to severe iodine deficiency, it should be cautiously recommended for the evaluation of iodine status in iodine sufficient to mildly iodine deficient regions.

Biomonitoring Equivalents for interpretation of urinary iodine

Iodine is an essential nutrient whose deficiency or excess exposure can cause adverse health effects. The primary sources of iodine exposure in the general population are iodized salt, dairy products, bread and sea food. Urinary iodine concentrations (UIC) have been measured by Canadian Health Measures Survey (CHMS) and US National Health and Nutrition Examination Survey (NHANES). The Institute of Medicine (IOM), the US Agency for Toxic Substances and Disease Registry (ATSDR) and World Health Organization (WHO) have established exposure guidance values for nutrition (IOM Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), WHO Recommended Nutrient Intake (RNI)) and toxicity (IOM Tolerable Upper Intake Level (UL); ATSDR Minimal Risk Level (MRL), WHO International Programme on Chemical Safety (IPCS) Tolerable Daily Intake (TDI)). Using a urinary excretion fraction of 0.9, Biomonitoring Equivalents (BE) for the EAR, RDA, UL and MRL were derived for adults (60, 100, 730 and 450 μg/L, respectively) and children (50, 80, 580 and 360 μg/L, respectively). The population median UIC values from NHANES and CHMS for adults (140–181, 122–126 μg/L, respectively) and children (232, 189 μg/L, respectively) were above the criteria for assessing iodine nutrition, indicating that US and Canadian populations are likely to have adequate population iodine nutrition. The median UIC from NHANES and CHMS do not exceed BE values derived from exposure guidance values for toxicity.

Urinary iodine concentration and thyroid hormones: Korea National Health and Nutrition Examination Survey 2013-2015.

An epidemiologic study that evaluated population's iodine nutrition status and its relationship with thyroid hormones is lacking in iodine-sufficient area. This nationwide study aimed to evaluate the iodine nutrition status in Korea and relationship between urine iodine concentration (UIC) and thyroid hormones. A total of 8318 subjects of the Korea National Health and Nutrition Examination Survey VI (2013-2015) with UIC and thyroid hormone evaluation were included. Median UIC level and estimated 24-h iodine intake were calculated. The prevalence of iodine deficiency or excess was obtained using estimated average requirement or above the tolerable upper intake level cut-point method by estimated iodine intake. We analyzed UIC with regard to age, sex, social economic status, and geographic characteristics. The median UIC in general population and estimated iodine intake in adult population were 293.9μg/L (above requirement according to World Health Organization classification) and 249.3μg/day, respectively. The prevalence of iodine deficiency and excess was 14.0 and 13.4%. The median UIC was higher among SAC [511 (299.9-948.5)] and lower among seventies [251.2 (98.9-761.6)] compared to other age groups. The median UIC increased with household income level (p for trend < 0.001). The subjects living in rural and inland region had lowest UIC among the enrolled subjects. The subgroups with higher median UIC were associated with higher mean TSH levels. This first nationwide study in Korea demonstrated that the median of UIC and estimated iodine intake lie at nearly 300µg/L and 250µg/day, respectively, which shows an overall excellent iodine nutrition.

Validation of a Capillary Electrophoresis Assay for Monitoring Iodine Nutrition in Populations for Prevention of Iodine Deficiency: An Interlaboratory Method Comparison.

A capillary electrophoresis (CE) assay was recently introduced as a new method for monitoring iodine nutrition in large-scale epidemiological studies. However, further tests revealed unanticipated matrix-dependent interferences when analyzing submicromolar levels of iodide in human urine as the predominate ionic form of dietary iodine. Herein, we describe a rigorous validation study that was used to identify sources of bias and establish modifications to the original CE method to improve method accuracy. An interlaboratory method comparison using CE with UV detection and inductively coupled plasma-mass spectrometry (ICP-MS) was performed to quantify urinary iodide concentrations (n = 71) independently at McMaster University and Hamilton General Hospital, as well as the CDC as part of their quality assurance program. A positive bias in the original CE method was indicated, and buffer conditions were subsequently optimized to overcome matrix interferences for reliable iodine status determination. Positive bias in CE was attributed to variable concentrations of sulfate, a major urinary anion interference with similar mobility to iodide under the conditions originally reported. By increasing the concentration of α-cyclodextrin in the background electrolyte, the CE method was able to tolerate urinary sulfate over its normal physiological range without loss in signal response for iodide. The optimized CE assay generated results that were consistent with ICP-MS using 2 different internal standards (187Re and 130Te) with a median bias under 10%. CE offers a simple, selective, and cost-effective separation platform for surveillance of the iodine status of a population requiring only small volumes (<10 μL) of biobanked urine specimens, which is comparable to previously validated screening methods currently used in global health initiatives for prevention of iodine deficiency disorders.

Reliability of thyroglobulin in serum compared with urinary iodine when assessing individual and population iodine nutrition status.

The occurrence of thyroid disorders relies on I nutrition and monitoring of all populations is recommended. Measuring I in urine is standard but thyroglobulin in serum is an alternative. This led us to assess the reliability of studies using serum thyroglobulin compared with urinary I to assess the I nutrition level and calculate the number of participants needed in a study with repeated data sampling in the same individuals for 1 year. Diet, supplement use and life style factors were assessed by questionnaires. We measured thyroglobulin and thyroglobulin antibodies in serum and I in urine. Participants were thirty-three Caucasians and sixty-four Inuit living in Greenland aged 30-49 years. Serum thyroglobulin decreased with rising I excretion (Kendall's τ -0·29, P=0·005) and did not differ with ethnicity. Variation in individuals was lower for serum-thyroglobulin than for urinary I (mean individual CV: 15·1 v. 46·1 %; P<0·01). It required 245 urine samples to be 95 % certain of having a urinary I excretion within 10 % of the true mean of the population. For serum-thyroglobulin the same precision required 206 samples. In an individual ten times more samples were needed to depict I deficiency when using urinary I excretion compared with serum-thyroglobulin. In conclusion, more participants are need to portray I deficiency in a population when using urinary I compared with serum-thyroglobulin, and about ten times more samples are needed in an individual. Adding serum-thyroglobulin to urinary I may inform surveys of I nutrition by allowing subgroup analysis with similar reliability.

Iodine deficiency a persisting problem: assessment of iodine nutrition and evaluation of thyroid nodular pathology in Portugal

The goal of eliminating iodine deficiency (ID) by the year 2000 has still not been achieved in several countries. More than 2 billion people worldwide (over 260 million school age children) remain ID. In Europe, there are still countries, such as Portugal, without national general population data on iodine nutrition (IN). This study aims at evaluating combined complementary data of the IN of the general population through urinary iodine concentration (UIC) and the thyroid histology profile from the inland region of Beira Interior (BI), in Portugal. UIC from a population sample of 214 volunteers (131 females and 83 males), with ages ranging from 8 to 97years (mean 51.5years±SD 20.74years), from BI was determined; the thyroid histology pattern in BI (6-year period) was evaluated; and the iodine content of the largest surface water reservoir of BI, never previously reported, was measured. Median UIC of 62.6μg/L was measured. Over 92% of the population had UIC less than 100μg/L. From 279 histology reports evaluated, the incidence of the different types of thyroid nodular pathology in BI was established. There were 60 histologic diagnoses of malignancy. The observed ratio of papillary to follicular carcinoma relatively close to 1 and the fairly high percentage of anaplastic carcinomas are characteristic of ID areas. The findings of this first general population study on IN from the inland region of BI, Portugal, document significant ID. This problem, with its serious public health implications, could be corrected by having affordable iodised salt widely and generally available and by promoting a proactive population attitude generated by ample public information and educational programs as to the negative consequences of ID.

Iodine deficiency in pregnant women in Europe

The adverse effects of iodine deficiency in populations (decreased IQ, goiter, hypothyroidism, and hyperthyroidism) are easily corrected with salt iodisation. 1 Zimmermann MB Boelaert K Iodine deficiency and thyroid disorders. Lancet Diabetes Endocrinol. 2015; 3: 286-295 Summary Full Text Full Text PDF Scopus (381) Google Scholar However, these adverse effects continue to be a problem in many countries, with an estimated 1·9 billion people at risk worldwide. 2 Zimmermann MB Andersson M Update on iodine status worldwide. Curr Opin Endocrinol Diabetes Obes. 2012; 19: 382-387 Crossref PubMed Scopus (174) Google Scholar All European countries endorsed the goal of elimination of iodine deficiency at the 1992 World Health Assembly (WHA), and the 2005 WHA again called on all Member States to regularly monitor iodine nutrition. WHO recommends use of the median urinary iodine concentration in national or regional surveys to classify iodine nutrition in populations. 4 World Health Organization/United Nations Children's Fund/International Council for the Control of Iodine Deficiency Disorders (WHO/UNICEF/ICCIDD)Assessment of iodine deficiency disorders and monitoring their elimination. A guide for programme managers. 3rd edition. WHO, Geneva2007 Google Scholar Adequate iodine nutrition in the general population is shown by a median urinary iodine concentration for school-age children (aged 6–12 years) of 100–299 μg/L. 4 World Health Organization/United Nations Children's Fund/International Council for the Control of Iodine Deficiency Disorders (WHO/UNICEF/ICCIDD)Assessment of iodine deficiency disorders and monitoring their elimination. A guide for programme managers. 3rd edition. WHO, Geneva2007 Google Scholar Despite calls to monitor and eliminate Iodine deficiency, during the past decade, compared with other WHO regions, Europe has had the highest percentage of iodine-deficient school-age children, 3 Iodine Global Network http://www.ign.org Google Scholar despite its wealth and its high standards of health care. In 2015, in the WHO European region, only 47·9 million (66%) of the region's 72·1 million school-age children have adequate iodine intakes. 3 Iodine Global Network http://www.ign.org Google Scholar

Iodine nutritional status in Brazil: a meta-analysis of all studies performed in the country pinpoints to an insufficient evaluation and heterogeneity.

Iodine deficiency disorder (IDD) is the result of an inadequate dietary intake of iodine, which physiological consequences are endemic goiter and thyroid dysfunction. The objective of this study was to a analyze studies that assessed the status of Brazil's population iodine nutrition and IDD prevalence. Systematic review using PRISMA statement. Electronic database: PubMed, Medline, SciELO and Lilacs. Quality of studies: Newcastle-Ottawa Scale. Meta-analysis was carried out with R Core Team Statistical Software, version 3.1.0 (2014). The summary measure (WMD) and its confidence interval (CI) of 95% were calculated. The "Funnel plot" graph assessed publication bias and heterogeneity. Seventeen papers were eligible: pregnant women (2), school children (9), adults/elderly (4) and preschool children/infants (2). Geographic distribution: North (1), Northeast (1), Midwest (2), Southeast (13), South (3). Twenty-three thousand two hundred seventy-two subjects were evaluated between 1997 and 2013 and all have use urinary iodine (UI) measurement. However, only 7 studies could be included in meta-analysis, all from Southeast region. The overall prevalence of IDD in school children in southeast region was 15.3% (95% CI, 13-35%), however this data had an important heterogeneity, expressed by the I2 Statistic of 99.5%. Only few studies have been performed and enrolled populations from south/southeast region of Brazil. The actual IDD prevalence analysis is complex because it was detected bias due influence of individual studies and very high heterogeneity. IDD might still be high in some areas but this remained unknown even after this meta-analysis evaluation. The generation of a national program for analysis of iodine status in all regions is urgently required.

Prevalence of iodine deficiency among adult population residing in Rural Ballabgarh, district Faridabad, Haryana.

Community-based surveys are essential to monitor iodine deficiency disorders (IDD) program at both the state and national levels. There is paucity of information on population iodine nutrition status in Haryana state using standard methods. A cross-sectional study was conducted in villages of Comprehensive Rural Health Services Project (CRHSP), Ballabgarh, Haryana, India. A total of 465 randomly selected individuals were assessed for urinary iodine concentration (UIC) by microplate method and household salt iodine content using iodometric titration. Of the interviewed households, 73% were using adequately iodized salt (≥15 ppm). Iodine nutrition was deficient in 17% respondents (UIC <100 μg/L); 20.2% among males and 13.9% among females. Iodine intake of the study population as measured by UIC was adequate but nearly one-fourth of households in the study population were consuming inadequately iodized salt. The availability and access to adequately iodized salt in the study population should be improved by strengthening regulatory monitoring.

Urinary Iodine Excretion In Pregnancy: A Pilot Study in The Region of Nepal

Pregnancy is accompanied by profound alterations in the thyroid economy and the relative iodine deficiency. The median Urinary Iodine Excretion (UIE) is the most reliable indicator of the population's iodine nutrition. The physiological alterations in normal pregnancy, such as an increased glomerular filtration rate, potentially invalidate UIE as an assessment tool in pregnancy. To assess the Urinary Iodine Excretion (UIE) in pregnant mothers and to enquire about the current status of their iodised salt intake. We carried out a cross-sectional study in which urine samples were collected from 45 pregnant mothers who were admitted to the antenatal ward. The iodine level in the urine was analysed by a method which was provided by Singh and Ali, to determine the Urinary Iodine Excretion (UIE). A questionnaire was introduced to document the status of the dietary intake of iodised salt. The UIE was expressed in median (interquartile) and the other data are expressed in frequency and percentage. Fisher Exact test was applied to compare between UIE and iodine intake. Thirteen (28.88%) pregnant mothers had UIEs of <150 μg/L, which were below the cut-off point of the UIE for pregnant mothers. Overall, 33 mothers were from the Terai region; among them, one third had UIEs of <150 μg/L. Among the 45 pregnant women, 15 (33.34%) were not using iodised salt and the rest were using iodised salt. Among those who were using iodised salt (30 out of 45), 8 pregnant women had UIEs of <150 μg/L and among those who were not using iodised salt, 5 pregnant women had UIEs of < 150 μg/L. The UIE was below 150μg/L in a substantial percentage (28.89%) of pregnant women of the Terai region, regardless of their intake of iodised salt.

Assessment of iodine nutrition in populations: past, present, and future

Iodine status has been historically assessed by palpation of the thyroid and reported as goiter rates. Goiter is a functional biomarker that can be applied to both individuals and populations, but it is subjective. Iodine status is now assessed using an objective biomarker of exposure, i.e., urinary iodine concentrations (UICs) in spot samples and comparison of the median UIC to UIC cut-offs to categorize population status. This has improved standardization, but inappropriate use of the crude proportion of UICs below the cut-off level of 100 µg/L to estimate the number of iodine-deficient children has led to an overestimation of the prevalence of iodine deficiency. In this review, a new approach is proposed in which UIC data are extrapolated to iodine intakes, adjusted for intraindividual variation, and then interpreted using the estimated average requirement cut-point model. This may allow national programs to define the prevalence of iodine deficiency in the population and to quantify the necessary increase in iodine intakes to ensure sufficiency. In addition, thyroglobulin can be measured on dried blood spots to provide an additional sensitive functional biomarker of iodine status.

Universal Salt Iodization in the Central and Eastern Europe, Commonwealth of Independent States (CEE/CIS) Region during the Decade 2000–09: Experiences, Achievements, and Lessons Learned

By 2000, the global track record on universal salt iodization (USI) indicated 26% access to adequately iodized salt in the Central and Eastern Europe, Commonwealth of Independent States (CEE/ CIS) Region. Aimed at extracting lessons learned, this study examined experiences, achievements, and outcomes of USI strategies in CEE/CIS countries during the subsequent decade. Information from the design, timing, execution, outputs, multi-sector management and results of actions by national stakeholders yielded 20 country summaries. Analysis across countries used a LogFrame Analysis typical for public nutrition development. By 2009, USI strategies had reached the target and population iodine nutrition shown adequate levels in 9 countries, while in 6 others, USI was close and/or population iodine status showed only minor imperfection. True USI, i.e., iodization of salt destined both for the food industry and the household, had been made mandatory in 13 of these 15 countries. In the Balkan area, USI and iodine nutrition advanced more than in CIS. Of the 20 sample countries, 17 (85%) had exceeded the mark of 50% adequate access, while the overall regional score reached 55% by 2010. Experience from this region suggests that strong partnership collaboration, a new concept in post-Soviet societies, was a major success factor. Voluntary iodization or focusing on household salt alone was less likely conducive for success. Achieving optimum iodine nutrition required the setting of proper iodine standard Weak political leadership insistence in the Russian Federation and Ukraine to embrace USI is the main factor why the region remains behind in the global progress.

Strategy for elimination of iodine deficiency in Belarus: evaluation of 10 years experience

Article presents results of implementation of successful program of elimination of iodine deficiency in Belarus. Government decree (2001) requires mandatory use of iodized salt in food industry and public catering. While retail trade of non-iodized salt is not prohibited, all foods shops must have iodized salt on sale. All these measures resulted in increase of iodized salt consumption: 94% of house-holds in Belarus were using iodized salt. Iodine nutrition of population also sig-nificantly improved: median urinary iodine levels in general population (school-children) reached 169 mcg/l and in pregnant women – 224 mcg/l. Endemic goiter morbidity decreased significantly in children, adolescents and adults as well as frequency of transitory thyroid dysfunctions in newborns. Belarus experience in prevention of iodine deficiency can be used by other industrialized countries of Europe and rest of the world.

Urinary Iodine Concentrations Indicate Iodine Deficiency in Pregnant Thai Women but Iodine Sufficiency in Their School-Aged Children

The median urinary iodine concentration (UI) in school-aged children is recommended for assessment of iodine nutrition in populations. If the median UI is adequate in school-aged children, it is usually assumed iodine intakes are also adequate in the remaining population, including pregnant women. But iodine requirements sharply increase during pregnancy. In this study, our aim was to measure UI in pairs of pregnant women and their school-aged children from the same family, who were sharing meals, to directly assess whether a household food basket that supplies adequate iodine to school-aged children also meets the needs of pregnant women. UI was measured in spot urine samples from pairs (n = 302) of healthy pregnant mothers and their school-aged children in metropolitan Bangkok, Thailand. A dietary questionnaire was completed. The UI [median (range)] in the pregnant women {108 (11-558) microg/L [0.85 (0.086-4.41) micromol/L]} were lower than those of their school-aged children {200 (25-835) microg/L [1.58 (0.20-6.52) micromol/L]} (P < 0.001), indicating optimal iodine status in the children but mild-to-moderate iodine deficiency in their pregnant mothers. The estimated iodine intakes in the 2 groups were in the range of 130-170 microg/d. There was a modest positive correlation between UI in the pairs (r = 0.253; P < 0.01). A higher frequency of seafood meals was a significant predictor of UI in both groups, but household use of iodized salt was not. These data suggest the median UI in school-aged children should not be used as a surrogate for monitoring iodine status in pregnancy in central Thailand; pregnant women should be directly monitored.

Influence of iodine on the reference interval of TSH and the optimal interval of TSH: results of a follow‐up study in areas with different iodine intakes

The aim of the present study was to evaluate whether the status of iodine nutrition influences the TSH concentration in a selected Chinese reference population according to the criteria proposed by National Academy of Clinical Biochemistry (NACB) and regular thyroid ultrasonography, to establish a new reference interval of TSH based on the wide variation of iodine nutrition in populations, and to identify an optimal interval of TSH by following up the cohort with normal TSH concentrations at baseline. The study was conducted in Panshan, Zhangwu and Huanghua, the regions with mildly deficient, more than adequate and excessive iodine intake, respectively. Of the 3761 unselected subjects who were enrolled at baseline, 2237 met the criteria for a reference population. Of 3048 subjects with normal serum TSH at baseline, 2727 (80.0%) participated in the 5-year follow-up study. TSH and thyroid autoantibodies in serum and iodine in urine were measured, and B-mode ultrasonography of the thyroid was performed. In the reference population, there was a urinary iodine-related increment of serum TSH levels (r = 0.21, P = 0.000), and the mean levels of TSH in Panshan, Zhangwu and Huanghua were 1.15, 1.28 and 1.93 mIU/l, respectively (P = 0.000), corresponding to the rising regional iodine intake. Based on the overall data, we obtained a reference interval of 0.3-4.8 mIU/l. TSH concentrations obtained in the follow-up study correlated well with those at baseline (r = 0.58, P = 0.000). A baseline serum TSH > 1.9 mIU/l was associated with an increased incidence of development of supranormal TSH and a baseline serum TSH < 1.0 mIU/l was associated with an increased incidence of subnormal TSH development. Iodine nutrition is an important factor associated with TSH concentration even in the rigorously selected reference population. Baseline TSH of 1.0-1.9 mIU/l is an optimal interval with the lowest incidence of abnormal TSH in 5 years.

The Average of Dietary Iodine Intake due to the Ingestion of Seaweeds is 1.2 mg/day in Japan

The Average of Dietary Iodine Intake due to the Ingestion of Seaweeds is 1.2 mg/day in Japan