Assessment of iodine nutritional status and gestational thyroid function reference ranges during the first trimester of pregnancy in Taiwan.

BACKGROUND: Iodine nutrition is critical for fetal neurodevelopment in the first trimester of pregnancy, a period associated with dramatic changes in thyroid function. The aim of this study was to evaluate iodine nutritional status and thyroid function reference ranges in the first trimester in Taiwan. METHODS: Pregnant women aged 20 years and above in the first trimester were recruited in Taipei Veterans General Hospital, Taiwan from March 2019 to July 2022. Each participant provided a spot urine sample for measurement of urinary iodine concentration (UIC) and a blood sample for checkup of thyroid function and thyroid autoantibodies. A simple food frequency questionnaire was also completed. RESULTS: A total of 209 women with a mean age of 32.9 ± 4.4 years were enrolled. The median UIC was 160.9 µg/L (interquartile range [IQR]: 105.0-246.2 µg/L), indicating overall iodine sufficiency. The gestational thyroid function reference ranges were: thyroid stimulating hormone (TSH) (median: 0.93 [0.007-2.9] µIU/mL), free T4 (1.3 [0.93-2.2] ng/dL), free T3 (3.0 [2.3-5.0] ng/dL), total T4 (9.9 [6.4-16.9] ng/dL), and total T3 (135 [88-231] ng/dL). If the nonpregnant reference range of serum TSH was used, eight women (4.8%) would be misclassified as having subclinical hyperthyroidism, and two women (1.2%) with subclinical hypothyroidism would be missed. In multivariate analysis, nulliparous (adjusted odds ratio [OR] from model 1-3: 2.02, 2.05, 2.02; 95% CI, 1.08-3.77, 1.10-3.81, 1.11-3.66; p = 0.027, 0.023, 0.022, respectively) and multivitamin nonusers (adjusted OR from model 1-3: 1.86, 1.85, 1.78; 95% CI, 1.04-3.34, 1.03-3.32, 1.004-3.71; p = 0.038, 0.039, 0.049, respectively) had increased odds of having lower UIC levels <150 µg/L. CONCLUSION: The iodine nutritional status in the first trimester is adequate in Taiwan; however, certain subgroups such as nulliparous and multivitamin nonusers are still at risk for iodine deficiency. Gestational thyroid function reference ranges are needed for correct diagnosis of thyroid dysfunction in pregnancy.

Comparison of body iodine pool assessment methods before radioiodine therapy.

INTRODUCTION AND OBJECTIVES: Radioactive iodine therapy (RAIT) is recommended to reduce the risk of recurrence and metastasis in patients with intermediate-high risk differentiated thyroid cancer (DTC). In preparation for RAIT, stimulation of thyroid-stimulating hormone and reduction of body iodine pool are important for treatment success. For this purpose, patients are asked to reduce their iodine intake before RAIT, and the body iodine pool can be evaluated by measuring iodine excretion in urine before treatment. The aim of our study is to compare the methods used to measure the body iodine pool in the evaluation of the restricted iodine diet (RID) effectiveness applied in the RAIT preparation. PATIENTS AND METHODS: Eighty DTC patients discontinued levothyroxine three weeks before RAIT and followed up with a RID two weeks before treatment. After two weeks of RID, all patients collected their 24-h urine the day before the RAIT date. Patients completed 24-h urine samples on the morning of the RAIT date and also provided a spot urine sample. The estimated 24-h creatinine excretion of the patients was calculated. Estimated 24-h urinary iodine excretion (UIE) was calculated using the spot urine iodine/creatinine (I/C) ratio of the patients. 24-h UIE, iodine concentration in spot urine, I/C ratios in spot urine and estimated 24-h UIE of the patients were analyzed by comparing with each other. RESULTS: In 99% of the patients, RID efficiency was sufficient according to 24-h UIE before RAIT. The mean 24-h UIE was 48.81 micrograms/day (mcg/day) in 24-h urine samples taken from the patients to evaluate the body iodine pool. The patients' iodine concentrations in spot urine, I/C ratios in spot urine, and estimated 24-h UIE were all statistically significantly lower than actual 24-h UIE, which was the reference method (p: 0.026 vs <0.001 vs 0.041). Moderate positive correlation between 24-h UIE and iodine concentration in spot urine (r: 0.440), I/C ratio in spot urine (r: 0.493), and estimated 24-h UIE (r: 0.560) found. The strongest correlation was obtained with the estimated 24-h UIE. CONCLUSION: The estimated 24-h UIE obtained by using the I/C ratio in spot urine can be used practically and safely as an alternative to UIE in 24-h urine, which is the gold standard method for evaluating body iodine pool.

Assessment of Joint Impact of Iodine, Selenium, and Zinc Status on Women's Third-Trimester Plasma Thyroid Hormone Concentrations.

BACKGROUND: Iodine is essential for synthesizing thyroid hormones, but other micronutrients are also required for optimal thyroid function. However, there is a lack of data on combined micronutrient status in relation to thyroid hormones in pregnancy. OBJECTIVES: We aimed to assess the joint associations of iodine, selenium, and zinc status with plasma concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) in pregnancy. METHODS: We included 531 pregnant women (aged 22-40 y) participating in a Swedish birth cohort who provided blood and spot urine samples in gestational weeks 27-33 (mean: 29). Associations of urinary iodine concentration (UIC), plasma selenium concentration, and plasma zinc concentration (measured by inductively coupled plasma mass spectrometry) with plasma hormone concentrations [total and free thyroxine (tT4, fT4), total and free triiodothyronine (tT3, fT3), and TSH] were explored with Bayesian kernel machine regression (BKMR; n = 516; outliers excluded) and multivariable-adjusted linear regression (n = 531; splined for nonlinear associations). RESULTS: Median (IQR) micronutrient concentrations were 112 µg/L (80-156 µg/L) for UIC, 67 µg/L (58-76 µg/L) for plasma selenium, and 973 µg/L (842-1127 µg/L) for plasma zinc; the former 2 median values were below recommended concentrations (150 µg/L and 70 µg/L, respectively). Mean ± SD TSH concentration was 1.7 ± 0.87 mIU/L, with 98% < 4 mIU/L. BKMR showed a positive trend of joint micronutrient concentrations in relation to TSH. Plasma zinc was most influential for all hormones but tT3, for which plasma selenium was most influential. In adjusted linear regression models, zinc was positively associated with tT4, tT3, and TSH, and <1200 µg/L also with fT4 and fT3. Selenium was inversely associated with fT3, and <85 µg/L with tT3. CONCLUSIONS: Pregnant women's plasma TSH concentrations in the early third trimester increased with increasing joint status of iodine, selenium, and zinc. Zinc and selenium were more influential than iodine for the hormone concentrations. Multiple micronutrients need consideration in future studies of thyroid hormone status.

Median Urinary Iodine Concentration in Colombian Children and Women is High and Related to Sociodemographic and Geographic Characteristics: Results from a Nationally Representative Survey.

BACKGROUND: Salt iodization has been mandatory in Colombia for over half a century. The iodine status of the population has not been recently evaluated using nationally representative data. OBJECTIVE: We estimated the median urinary iodine concentration (mUIC) of Colombian women and children overall and by individual and environmental characteristics. METHODS: Using data from spot urine samples collected in the 2015 Colombian National Nutrition Survey, we estimated mUIC in 24,248 boys and girls aged 1 to <13 y and 9122 women of reproductive age (WRA). Within each group, we compared mUIC by levels of sociodemographic, anthropometric, and geographic factors by using adjusted median differences with 95% CIs from quantile regression models. RESULTS: mUICs were 395 ± 3 µg/L among children and 381 ± 3 µg/L among WRA. Schoolchildren 5 to <13 y old had higher mUIC (407 ± 3 µg/L) than did preschoolers or toddlers. Girls had 21 µg/L (95% CI: -29, -14) lower mUIC than boys after adjustment. In addition, among children, mUIC was positively associated with household wealth and inversely associated with indigenous compared with mestizo ethnicity, living in the southern or Pacific compared with the central regions of Colombia, and altitude. Among WRA, mUIC was positively associated with obesity and inversely with age, indigenous compared with mestizo ethnicity, education, household wealth, living in southern compared with central Colombia, altitude, and alcohol intake frequency. CONCLUSION: Colombian children and WRA had mUIC well above conventional cutpoints of iodine excess. Whether excessive iodine affects other subpopulations and its functional consequences warrant urgent investigation.

Impact of Dietary Habit, Iodine Supplementation and Smoking Habit on Urinary Iodine Concentration During Pregnancy in a Catalonia Population.

(1) Background: The nutritional status of women during pregnancy can have a considerable effect on maternal and fetal health, and on the perinatal outcome. Aim: to assess the changes occurring in dietary iodine intake, potassium iodide supplementation, and smoking habit, and the impact of these changes on the urinary iodine concentration (UIC) during pregnancy in a population of women in Catalonia (Spain). (2) Methods: Between 2009-2011, an observational study included a cohort of women whose pregnancies were monitored in the public health system in the Central and North Metropolitan areas of Catalonia. Women received individual educational counseling, a dietary questionnaire was completed, and a urine sample was collected for iodine determination at each trimester visit. (3) Results: 633 (67.9%) women answered the questionnaire at all 3 visits. The percentage of women with a desirable UIC (≥150 µg/L) increased from the first to the second trimester and remained stable in the third (57.3%, 68.9%, 68%; p < 0.001). Analysis of the relationship between UIC≥150 µg/L and the women's dietary habits showed that the percentage with UIC ≥150 µg/L increased with greater consumption of milk in the first trimester, and the same was true for iodized salt use in all three trimesters and iodine supplementation in all three. (4) Conclusion: During pregnancy, increased intake of milk, iodized salt, and iodine supplements were associated with an increase in the UIC.

Changing Dietary Habits in Veneto Region over Two Decades: Still a Long Road to Go to Reach an Iodine-Sufficient Status.

Background: Fifteen years after a nationwide voluntary iodine prophylaxis program was introduced, the aims of the present study were: (a) to obtain an up-to-date assessment of dietary iodine intake in the Veneto region, Italy; and (b) to assess dietary and socioeconomic factors that might influence iodine status. Methods: Urinary iodine concentration (UIC) was obtained in 747 school students (median age 13 years; range: 11-16 years). Results: The median UIC was 111 µg/L, with 56% of samples ≥ 100 µg/L, but 26% were < 50 µg/L, more frequently females. Iodized salt was used by 82% of the students. The median UIC was higher among users of iodized salt than among non-users, 117.0 ug/L versus 90 ug/L (p = 0.01). The median UIC was higher in regular consumers of cow's milk than in occasional consumers, 132.0 µg/L versus 96.0 µg/L (p < 0.01). A regular intake of milk and/or the use of iodized salt sufficed to reach an adequate median UIC, although satisfying only with the combined use. A trend towards higher UIC values emerged in regular consumers of cheese and yogurt. Conclusion: Iodine status has improved (median UIC 111.0 µg/L), but it is still not adequate as 26% had a UIC < 50 µg/L in the resident population of the Veneto region. A more widespread use of iodized salt but also milk and milk product consumption may have been one of the key factors in achieving this partial improvement.

A systematic review and meta-analysis of 24-h urinary output of children and adolescents: impact on the assessment of iodine status using urinary biomarkers.

PURPOSE: Urinary iodine concentration (UIC (µg/ml) from spot urine samples collected from school-aged children is used to determine the iodine status of populations. Some studies further extrapolate UIC to represent daily iodine intake, based on the assumption that children pass approximately 1 L urine over 24-h, but this has never been assessed in population studies. Therefore, the present review aimed to collate and produce an estimate of the average 24-h urine volume of children and adolescents (> 1 year and < 19 years) from published studies. METHODS: EBSCOHOST and EMBASE databases were searched to identify studies which reported the mean 24-h urinary volume of healthy children (> 1 year and < 19 years). The overall mean (95% CI) estimate of 24-h urine volume was determined using a random effects model, broken down by age group. RESULTS: Of the 44 studies identified, a meta-analysis of 27 studies, with at least one criterion for assessing the completeness of urine collections, indicated that the mean urine volume of 2-19 year olds was 773 (654, 893) (95% CI) mL/24-h. When broken down by age group, mean (95% CI) 24-h urine volume was 531 mL/day (454, 607) for 2-5 year olds, 771 mL/day (734, 808) for 6-12 year olds, and 1067 mL/day (855, 1279) for 13-19 year olds. CONCLUSIONS: These results demonstrate that the average urine volume of children aged 2-12 years is less than 1 L, therefore, misclassification of iodine intakes may occur when urine volumes fall below or above 1 L. Future studies utilizing spot urine samples to assess iodine status should consider this when extrapolating UIC to represent iodine intakes of a population.

Does relatively low iodine intake contribute to thyroid cancer? An ecological comparison of epidemiology.

Research on the relationship between iodine intake and thyroid cancer (TC) risk is limited, and the findings are inconclusive. The objective of this study was to provide emerging evidence for the association between iodine intake and TC risk in a Chinese population.An ecological study of epidemiology is used to compare the iodine intake among populations with different TC incidence in Zhoushan, China. Incidence rates of TC were investigated and compared among four counties of the Zhoushan Islands from 2014 to 2018. Iodized salt consumption rate and the level of urinary iodine concentration (UIC) were analyzed for pupils and pregnant women from four counties.During 2014 to 2018, a total of 2495 new cases of TC were diagnosed in Zhoushan Islands. The mean crude incidence rate of TC was 51.29 per 100,000 inhabitants, and the standardized (world population) incidence rate (SIR) was 31.34 per 100,000 population. Incidence rates (SIR and crude incidence rates) were significantly higher in women than in men (χ test, P < .05). Both male and female, the incidence of TC in Daishan County is higher than the other three counties of Zhoushan. Iodized salt consumption rate and median UIC in pupils and pregnant women in Daishan County was significantly lower than the other three counties (χ test and Kruskal-Wallis test, all P < .05). The population with high TC incidence has a lower iodized salt consumption and a lower level of UIC compare with the relative low TC incidence populations.The low consumption of iodized salt with mild iodine deficiency may contribute to explain the exceptionally high incidence of TC in Daishan County. Further subtle designed studies are needed to provide additional insights into the epidemiology and etiology of TC and help identify the safe limit of iodine intake for prevention.

Optimal Assessment and Quantification of Iodine Nutrition in Pregnancy and Lactation: Laboratory and Clinical Methods, Controversies and Future Directions.

Iodine intake must be boosted during pregnancy to meet the demands for increased production and placental transfer of thyroid hormone essential for optimal foetal development. Failure to meet this challenge results in irreversible brain damage, manifested in severity from neurological cretinism to minor or subtle deficits of intelligence and behavioural disorders. Attention is now being focused on explaining observational studies of an association between insufficient iodine intake during pregnancy and mild degrees of intellectual impairment in the offspring and confirming a cause and effect relationship with impaired maternal thyroid function. The current qualitative categorisation of iodine deficiency into mild, moderate and severe by the measurement of the median urinary iodine concentration (MUIC) in a population of school-age children, as a proxy measure of dietary iodine intake, is inappropriate for defining the degree or severity of gestational iodine deficiency and needs to be replaced. This review examines progress in analytical techniques for the measurement of urinary iodine concentration and the application of this technology to epidemiological studies of iodine deficiency with a focus on gestational iodine deficiency. We recommend that more precise definitions and measurements of gestational iodine deficiency, beyond a spot UIC, need to be developed. We review the evidence for hypothyroxinaemia as the cause of intrauterine foetal brain damage in gestational iodine deficiency and discuss the many unanswered questions, from which we propose that further clinical studies need to be designed to address the pathogenesis of neurodevelopmental impairments in the foetus and infant. Agreement on the testing instruments and standardization of processes and procedures for Intelligence Quotient (IQ) and psychomotor tests needs to be reached by investigators, so that valid comparisons can be made among studies of gestational iodine deficiency and neurocognitive outcomes. Finally, the timing, safety and the efficacy of prophylactic iodine supplementation for pregnant and lactating women needs to be established and confirmation that excess intake of iodine during pregnancy is to be avoided.

Iodine status of euthyroid adults: A cross-sectional, multicenter study.

BACKGROUND: Iodine, an essential nutrient, is the most important trace element in thyroid hormone synthesis and maintenance of thyroid function. This study investigated the iodine nutrition status in healthy Chinese adults and assessed the relationship between urinary iodine concentration (UIC) and thyroid hormone levels. METHODS: A cross-sectional, multicenter study was conducted between October 2017 and January 2018, with 1017 adults recruited from five cities in China. All subjects underwent thyroid ultrasonography, and only those with normal results were included in the study. UICs were measured by inductively coupled plasma mass spectroscopy and adjusted using urine creatinine levels. Thyroid hormone levels were measured using an automated immunoassay analyzer. RESULTS: The median UIC and adjusted UIC were 134.0 µg/L and 114.2 µg/g, respectively. UIC was not significantly different between males and females (P = 0.737). However, the adjusted UIC was significantly different between sexes (P < 0.001). The median UIC was higher than 100 µg/L. According to the World Health Organization criterion (100 µg/L), the total prevalence of iodine deficiency is 33.1% (n = 271). The prevalence rates of iodine deficiency in our study were 33.2% and 32.9% in males and females, respectively, and had no difference between sexes and among cities (P > 0.05). Serum thyroid-stimulating hormone (TSH) levels increased when UIC increased. The Kruskal-Wallis test showed no significant differences in free triiodothyronine, free thyroxine, and TSH, with different levels of UIC (all P > 0.05). CONCLUSIONS: Chinese adults with normal thyroid structure have relatively sufficient iodine levels.

Socioeconomic status of the population - a prime determinant in evaluating iodine nutritional status even in a post salt iodization scenario.

Background To compare the state of iodine nutrition among school age children (SAC) in high- (HSGs) and low-socioeconomic groups (LSGs) during a post iodation scenario in Kolkata. Methods Clinical examinations of the goiter, median urinary iodine (MUI), mean urinary thiocyanate (MUSCN) in SAC (6-12 years) from both sexes in the different socioeconomic groups were carried out and the iodine content of edible salt was measured. Results A total of 5315 SAC, of which 2875 SAC were from a HSG and another 2440 SAC from an LSG were clinically examined for goiter. In the HSGs the total goiter prevalence (TGP) was 3.2% and in the LSGs the TGP was 9.1% and the difference was statistically significant (p<0.001). The MUI of the HSGs was 242 µg/L as compared to 155 µg/L in the LSGs (p<0.001). MUSCN of the HSGs was 0.77±0.45 mg/dL while in the LSGs it was 0.94±0.44 mg/dL and the difference was statistically significant (p<0.01). In the HSGs 19.4% salt samples had 15-30 ppm iodine and 80.6% salt samples were above 30 ppm as compared to 26.3% salt samples which were below 15 ppm, 37.1% salt samples which were between 15 and 30 ppm and 36.6% salt samples which were above 30 ppm in the LSGs. Conclusions The population of the LSGs was clinically mildly iodine deficient having no biochemical iodine deficiency while in the HSGs it was more than the adequate requirement and the HSG children are possibly at risk of excess iodine induced thyroid diseases. Existing goiter prevalence in the LSGs was from their relatively high consumption of dietary goitrogens. Therefore, socioeconomic status plays a pivotal role in the management of iodine nutrition even in a post salt iodation scenario.

Consistent Iodine Status Assessment in Chinese Adults by Different Spot Urinary Iodine Concentrations in a Day Together With Corresponding Correction Coefficients.

Objective: The aim of this research was to determine the correction coefficients of different spot urinary iodine concentrations (UICs) in a day to predict the early morning UIC, to make the different spot UICs of a day comparable in assessing iodine status in the same population. Methods: In total, 424 participants aged 18 to 28 years were recruited from Tianjin, China. Three spot urine samples were collected from each participant during three periods of the day (6:30-7:00, 10:00-10:30, and 16:00-16:30). A total of 1272 urine samples were collected. A 24-hour dietary record was reported by each participant for 3 consecutive days. Results: Both the UICs at 10:00-10:30 and 16:00-16:30 were higher than that at 6:30-7:00 (181.75 or 198.15µg/L vs 157.69 µg/L; all p < 0.05). Bland-Altman plot showed no good agreements between the other two spot UICs and that at 6:30-7:00 with both Bland-Altman indexes of 7.1%. Correction coefficients used to predict UIC at 6:30-7:00 from the UIC at 10:00-10:30 and 16:00-16:30 were 0.9231 and 0.8592, respectively. The predicted UICs at 6:30-7:00 by using the UIC at 10:00-10:30 and 16:00-16:30 both had no statistically significant difference with the actual UIC at 6:30-7:00 (all p > 0.05). Bland-Altman plot showed good agreements between the predicted UICs and actual UICs at 6:30-7:00 with both Bland-Altman indexes of 4.5%. Conclusions: It was reliable to predict the early morning UIC using correction coefficients of other spot UIC of the day, which gave a new idea for standardizing the methodology of surveys assessing iodine status of a population.

The assessment of iodine status - populations, individuals and limitations.

Iodine deficiency is a significant global health concern, and the single greatest cause of preventable cognitive impairment. It is also a growing public health concern in the UK particularly among pregnant women. Biomarkers such as urinary iodine concentration have clear utility in epidemiological studies to investigate population-level iodine status, but determination of iodine status in individuals is much more problematic with current assays. This article reviews the available biomarkers of iodine status and their relative utility at the level of both populations and individuals for the investigation of iodine deficiency and iodine excess.

Assessment of Iodine Nutritional Status of School-Age Children in Kolkata District of West Bengal State in Post-Iodation Scenario.

To evaluate the state of iodine nutrition in post-iodation scenario, 3500 children were examined clinically for endemic goitre. Iodine and thiocyanate were measured in 240 urine samples; iodine content in 210 salt samples was measured. Total goitre prevalence was 6.1%. Median urinary iodine level was 21.80 µg/dl, and mean (±SD) urinary thiocyanate was 0.89 ± 0.49 mg/dl. Iodine content of only 11.9% salt samples was below recommended level of 15 ppm, 25.2% was between 15 and 30 ppm and 62.9% was >30 ppm. Iodine deficiency disorders are thus clinically mild public health problem of the studied population; however, they have no biochemical iodine deficiency. Studied population found exposed to thiocyanate load that might be the possible cause for persistence of endemic goitre. People of Kolkata should be advised to eat commonly consumed goitrogenic foods after boiling and decanting the water. Periodical monitoring and evaluation of iodine status should be mandatory.

Avaliação do status nutricional de iodo em gestantes atendidas no pré-natal do Hospital das Clínicas da Universidade Federal de Minas Gerais / Assessment of the nutritional status of iodine in pregnant women attended at the prenatal care at the Hospital das Clínicas of the Federal University of Minas Gerais

As disfunções tireoidianas durante a gestação cursam com maior morbidade materno-fetal. Uma das causas de disfunção tireoidiana é a deficiência ou excesso de iodo. Durante a gestação há um aumento da produção de hormônios tireoidianos, um incremento significativo do clearance renal de iodo e aumento do turnover de tiroxina (T4) pela deiodinase tipo 3 placentária na 2ª metade da gestação, ocasionando assim, uma necessidade aumentada de iodo. O objetivo deste estudo foi avaliar o estado nutricional de iodo em gestantes atendidas no pré-natal do Hospital das Clínicas da UFMG. Analisamos a concentração urinária de iodo em 30 gestantes com gestação única e idade gestacional menor que 20 semanas. Foram coletadas amostras únicas ocasionais de urina para dosagem da concentração urinária de iodo através do método de plasma indutivamente acoplado com detector de massas. A mediana da concentração urinária de iodo das gestantes estudadas foi de 216,73 mcg/L, que está adequada para o grupo segundo a Organização Mundial de Saúde (OMS). Esse estudo demonstra que apesar do aumento da demanda de iodo pelas gestantes e da recomendação da ANVISA (Agência Nacional de Vigilância Sanitária) da redução dos níveis de iodação do sal, a população de gestantes atendidas no ambulatório de pré-natal de risco habitual do Instituto Jenny de Andrade Faria de Atenção à Saúde do Idoso e da Mulher da Universidade Federal de Minas Gerais é considerada suficiente em iodo. Apesar de uma maior amostragem ser necessária para a confirmação destes achados, acreditamos que é cedo para recomendar a suplementação universal de iodo para as gestantes brasileiras e mais estudos precisam ser realizados para uma conclusão. A suplementação de iodo para gestantes em áreas suficientes em iodo está associada aos riscos da exposição excessiva de iodo ao feto.

During pregnancy, there is an increased of thyroid hormone, a significant increased iodine renal clearance and increased thyroxine (T4) turnover by placental type 3 deiodinase in the second half of pregnancy, thus leading to increased iodine demand. The aim of this study was to evaluate the nutritional status of iodine in pregnant women attending in prenatal care at the hospital of the Universidade Federal de Minas Gerais. We analyzed urinary iodine concentration in 30 pregnant women with single pregnancy and gestational age less than 20 weeks. Casual single urine samples were collected for urinary iodine concentration measurement by inductively coupled plasma detector method. Median urinary iodine concentration of the pregnant women studied was 216.73 mcg/L, which is adequate for the group according to World Health Organization (WHO). This study demonstrates that despite the increased demand for iodine among pregnant women and ANVISA's recommendation to reduce salt iodine levels, the population of pregnant women attended at the Instituto Jenny Faria de Atenção à Saúde do Idoso e da Mulher of the Universidade Federal de Minas Gerais is considered sufficient in iodine. Although a larger sample is needed to consolidate these findings, we believe it is early to recommend universal iodine supplementation for Brazilian pregnant women and more studies are necessary to a conclusion. Iodine supplementation for pregnant women in accessible iodine areas is associated with risk of excessive iodine exposure to the fetus.

Assessment of thyroid function, ioduria and oxidative stress in women in the first trimester of pregnancy.

INTRODUCTION: adequate iodine intake during pregnancy is essential for the synthesis of thyroid hormones, which are important for the physiological functions of the mother and appropriate maturation of the central nervous system of the fetus. OBJECTIVE: the objective of the present study was to determine the levels of urinary iodine excretion and thyroid function, antioxidants and oxidative stress markers in pregnant women. METHODS: the study was conducted on 191 pregnant women and 62 non-pregnant women who were evaluated regarding nutritional status. Analyses of urinary iodine, of oxidative stress markers and thyroid function were performed, revealing iodine insufficiency in 81 pregnant women. RESULTS: there was no change in the thyroid stimulating hormone concentration in 89% of the pregnant women. Antithyroperoxidase antibody values were higher in the control group compared to the pregnant women's group (64.5% and 12.6%, respectively) and antithyroglobulin antibody values were also higher in the control group (11.6%). Assessment of oxidative stress revealed higher levels of advanced oxidation protein products, of total antioxidant capacity and of superoxide dismutase antioxidants in pregnant women. Classification of ioduria with respect to oxidative stress markers revealed lower α-tocopherol levels for the pregnant women with iodine insufficiency. CONCLUSION: on this basis, the results suggest that iodine insufficiency did not induce changes in thyroid stimulating hormone levels or antibodies and those pregnant women with adequate urinary iodine excretion had a better profile of the α-tocopherol antioxidant, indicating that iodine may play a significant role in antioxidant capacity during gestation.

Body mass index is associated with interleukin-1, adiponectin, oxidative stress and ioduria levels in healthy adults.

BACKGROUND: iodine contributes to maintain the balance of the reduced and oxidized species and is also required for thyroid hormones synthesis as triiodothyronine (T3), which regulates energy metabolism in adults. Increased body mass index (BMI) is associated with inflammatory markers, oxidative stress, and abnormalities in adipocytokines secretions that are associated with obesity and chronic disease. OBJECTIVE: the aim of the study is to investigate the association between ioduria, oxidative stress, total antioxidant status, adiponectin and interleukin-1 (IL-1) with BMI in healthy adults. METHODS: a cross-sectional study was performed in 114 healthy adult volunteers, aged 25-44 years, divided according to their BMI in three groups: normal weight (BMI < 25), overweight (BMI ≤ 25 to < 30), obesity (BMI ≥ 30). Adiponectin and IL-1 were measured by immune-enzymatic assays; oxidative stress, by determination of malondialdehyde (MDA); and total antioxidant status (TAS) and ioduria were measured by colorimetric assays. Statistical association was done by Spearman's test. RESULTS: overweight and obese subjects have higher serum levels of MDA, TAS and IL-1 vs normal weight subjects. Moreover, overweight and obese subjects have lower levels of iodine and adiponectin vs normal weight subjects. MDA was positively related only with obese subjects (r = 0.787, p = 0.008) and TAS with overweight (r = 0.398, p = 0.049) and obese subjects (r = 0.448, p = 0.030). In contrast, a reverse correlation with ioduria was found in obese subjects (r = 0.463, p = 0.001). Adiponectin was negatively related only in obese subjects (r = -0.477, p = 0.001), while, IL-1 was positively related with the increase of BMI (overweight r = 0.287, p = 0.050; and obesity r = 0.515, p = 0.006). CONCLUSION: alteration in IL-1, adiponectin and oxidative stress levels were found to be related to overweight and obesity; also, iodine levels decreased when BMI increased, contributing to loss of redox equilibrium. All this data may play an important role in etiopathogenesis of chronic disease related to the increase of BMI.

[Assessment of iodine nutritional status for pregnant women using adjusted urine creatinine from spot and 24-hour urine].

OBJECTIVE: To establish a reliable method of iodine nutritional assessment for pregnant women using the adjusted urinary creatinine of spot urine and 24-hour urine samples. METHODS: The spot urine in the morning at 8 00-11:30 and the following 24-hour urine samples of pregnant women were collected in Peking Union Medical College Hospital during March to October in 2016. The urinary iodine and urinary creatinine concentrations were determined. The estimated 24-hour urinary iodine excretion( 24-h UIE) was calculated using the urinary iodine/urinary creatinine( UIC/Cr) ratio of spot urine, and 24-hour urinary creatinine excretion( 24-h UCr E). RESULTS: There was a significant difference in the UIC, UIC/Cr ratio between spot urine and 24-h urine( P <0. 05). The UIC, UIC/Cr ratio of spot urine, and the estimated 24-h UIE all were significantly correlated with the real 24-h UIE( P < 0. 01), especially the estimated 24-h UIE were taking up 70%-80% for the real 24-h UIE in the period of gestation. CONCLUSION: The UIC, UIC/Cr, and the estimated 24-h UIE cannot directly replace the relevant values derived of the 24-hour urine samples. But the estimated 24-h UIE can reflect the iodine nutritional status of pregnant women in recent days, and the method could be a reliable reference for the iodine nutritional assessment of the pregnant women in practice.

Iodine Status Assessment in South African Adults According to Spot Urinary Iodine Concentrations, Prediction Equations, and Measured 24-h Iodine Excretion.

The iodine status of populations is conventionally assessed using spot urinary samples to obtain a median urinary iodine concentration (UIC) value, which is assessed against standard reference cut-offs. The assumption that spot UIC reflects daily iodine intake may be flawed because of high day-to-day variability and variable urinary volume outputs. This study aimed to compare iodine status in a sample of South African adults when determined by different approaches using a spot urine sample (median UIC (MUIC), predicted 24 h urinary iodine excretion (PrUIE) using different prediction equations) against measured 24 h urinary iodine excretion (mUIE). Both 24 h and spot urine samples were collected in a subsample of participants (n = 457; median age 55 year; range 18⁻90 year) in the World Health Organization Study on global AGEing and adult health (SAGE) Wave 2 in South Africa, in 2015. Kawasaki, Tanaka, and Mage equations were applied to assess PrUIE from predicted urinary creatinine (PrCr) and spot UIC values. Adequacy of iodine intake was assessed by comparing PrUIE and mUIE to the Estimated Average Requirement of 95 µg/day, while the MUIC cut-off was.

ASSESSMENT OF ADEQUATE IODINE AVAILA-BILITY TO THE POPULATION OF WEST KAZAKHSTAN BASED ON THE DATA OF INORGANIC IODINE IN URINARY EXCRETION.

Aim of research - to study the iodine supply of the region according to the degree of urinary iodine excretion in the West region of the Republic of Kazakhstan. Of 6493 schoolchildren participating in the study of the frequency of goiter, random sampling was applied to select 884 children to determine UIC. To establish the excretion of inorganic iodine in a single portion of urine in the field, express diagnostics, the "Iodine test" kits (manufactured in Ukraine), was applied. The collection of urine for the determination of UIC was carried out in disposable cups, hermetically sealed with stoppers to prevent the entry of iodine vapors into the test samples. The test was carried out immediately after urine collection. The concentration of iodine in the urine was expressed in µg/l. The method is semiquantitative and makes it possible to distinguish urine samples with iodine content below 70, from 70 to 100, from 100 to 300 and above 300 µg/L. The obtained data on the study of UIC in schoolchildren in the West Kazakhstan showed that the proportion of children with optimal urinary excretion of iodine (100-300 µg/L) is 62.67% (95% CI: 59.48-65.86%). Indices ranging from 100 to 200 µg/L were detected in 27.15% (95% CI: 24.22-30.08%, more than 200 µg/L and up to 300 µg/L - in 35.52% (95% CI: 32.37-38.68%) of schoolchildren. UIC exceeds 300 µg/L - in 18.89% (95% CI: 16.31-21.47%) of schoolchildren. Concentration of iodine in the urine of more than 400 µg/L was determined in 1.81% (95% CI: 0.93-2.69%) of children. Low excretion rates of iodine, less than 70 µg/L, were detected in 2.83 % (95% CI: 1.74-3.92%) of schoolchildren, and from 70 µg/L to 100 µg/L - in 13.8 % (95% CI: 11.53-16.07%). Thus, in 62.67% (95% CI: 59.48-65.86%) there is an optimal allocation of iodine in the urine, it can be considered that iodine status of the population of West Kazakhstan is adequate. In West Kazakhstan, in the absence of iodine deficiency, a strained goiter endemia remains.The formation of goiter endemia in the region does not exclude the influence of other strumogenic factors, which need further study.