Chronic Excess Iodine Intake Inhibits Bone Reconstruction Leading to Osteoporosis in Rats

BACKGROUND

Although iodine modulates bone metabolism in the treatment of thyroid disease, the effect of iodine intake on bone metabolism remains less known.

OBJECTIVE

This study evaluated the effect of excess iodine intake in rats on bone reconstruction in the 6th and 12th month of intervention.

METHOD

Rats were treated with different doses of iodinated water: the normal group (NI, 6.15 μg/d), 5-fold high iodine group (5HI, 30.75 μg/d), 10-fold high iodine group (10HI, 61.5 μg/d), 50-fold high iodine group (50HI, 307.5 μg/d), and 100-fold high iodine group (100HI, 615 μg/d). Thyroid hormone concentrations were determined by a chemiluminescent immunoassay. Morphometry and microstructure of bone trabecula were observed by hematoxylin and eosin staining and microcomputed tomography, respectively. Alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) staining were performed to evaluate the activity of osteoblasts and osteoclasts, respectively.

RESULTS

The 24-h urine iodine concentration increased with iodine intake. The rats in the HI groups had higher serum thyroid-stimulating hormone and decreased serum free thyroxine concentrations in the 12th month than the NI group (all P < 0.05). The percentage of the trabecular bone area and osteoblast perimeter in the 100HI group were significantly lower than those in the NI group (P < 0.05). Increased structure model index was observed in the 50HI and 100HI groups compared with the NI group in the 6th month and increased trabecular separation in the 12th month (all P < 0.05). ALP and TRAP staining revealed osteoblastic bone formation was reduced, and the number of TRAP+ multinucleated cells decreased with increasing iodine intake.

CONCLUSIONS

Excess iodine intake may increase the risk of hypothyroidism in rats. Chronic excess iodine intake can lead to abnormal changes in skeletal structure, resulting in reduced activity of osteoblasts and osteoclasts, which inhibits the process of bone reconstruction and may lead to osteoporosis.

Multimodel habitats constructed by perfusion and/or diffusion MRI predict isocitrate dehydrogenase mutation status and prognosis in high-grade gliomas

AIM

To determine whether tumour vascular and cellular heterogeneity of high-grade glioma (HGG) is predictive of isocitrate dehydrogenase (IDH) mutation status and overall survival (OS) by using tumour habitat-based analysis constructed by perfusion and/or diffusion magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Seventy-eight HGG patients that met the 2021 World Health Organization WHO Classification of Tumors of the Central Nervous System, 5th edition (WHO CNS5), were enrolled to predict IDH mutation status, of which 32 grade 4 patients with unmethylated O6-methylguanine-DNA methyltransferase (MGMT) promoter were enrolled for prognostic analysis. The deep-learning-based model nnU-Net and K-means clustering algorithm were applied to construct the Traditional Habitat, Vascular Habitat (VH), Cellular Density Habitat (DH), and their Combined Habitat (CH). Quantitative parameters were extracted and compared between IDH-mutant and IDH-wild-type patients, respectively, and the prediction potential was evaluated by receiver operating characteristic (ROC) curve analysis. OS was analysed using Kaplan-Meier survival analysis and the log-rank test.

RESULTS

Compared with IDH-mutants, median relative cerebral blood volume (rCBVmedian) values in the whole enhancing tumour (WET), VH1, VH3, CH1-4 habitats were significantly increased in IDH-wild-type HGGs (all p<0.05). Additionally, the accuracy of rCBVmedian values in CH1 outperformed other habitats in identifying IDH mutation status (p<0.001) at a cut-off value of 4.83 with AUC of 0.815. Kaplan-Meier survival analysis highlighted significant differences in OS between the populations dichotomised by the median of rCBVmedian in WET, VH1, CH1-3 habitats (all p<0.05).

CONCLUSIONS

The habitat imaging technique may improve the accuracy of predicting IDH mutation status and prognosis, and even provide a new direction for subsequent personalised precision treatment.

Chronic Iodine Intake Excess Damages the Structure of Articular Cartilage and Epiphyseal Growth Plate

This study aimed to explore the influence of excess iodine on the articular cartilage and epiphyseal growth plate in rats. Wistar rats (n = 200) were randomly divided into five groups with 40 rats in each: normal iodine (NI), 5-fold high iodine group (5HI), 10-fold high iodine group (10HI), 50-fold high iodine group (50HI), and 100-fold high iodine group (100HI). The rats were executed in 6 and 12 months. 24-h urinary iodine concentration (UIC) was monitored by arsenic-cerium catalytic spectrophotometry. The chemiluminescence method was used to determine the thyroid function. The pathological changes in the epiphyseal plate, articular cartilage, and thickness of the epiphyseal plate were observed. The mRNA expression of collagen II (ColII), collagen X, matrix metalloproteinase-13 (MMP-13), and fibroblast growth factor receptor 1 in articular chondrocytes was detected by RT-PCR. 24-h UIC increased as iodine intake increased. In the 12th month, there was a significant increase in serum sTSH and a decrease in serum FT4 in HI groups, compared to the NI group. There was a decrease in the number of proliferating cells in the epiphyseal plate and an increase in the number of mast cell layers. The chondrocytes appeared disorganized, and the tidal lines were disturbed or even broken. Growth plate thickness decreased with increasing iodine intake. Compared with the NI group, ColII and MMP-13 mRNA expression in chondrocytes in all HI groups significantly increased. Chronic iodine overdose increases the risk of hypothyroidism. Chronic iodine overdose leads to abnormal morphology of epiphyseal growth plates and articular cartilage, increasing the risk of osteoarthritis.

Community and individual iodine status assessment in premenopausal women in Shanxi, China: Repeated spot urine versus 24-hour urine

BACKGROUND AND OBJECTIVES

Urinary iodine is an essential index of iodine nutrition evaluation. To establish the number of repeated spot urine collections necessary to reflect individual iodine status over 2 months and assess its feasibility to serve as an independent indicator of individual iodine status.

METHODS AND STUDY DESIGN

We performed a longitudinal, 2-months study from May to June in 2015 of 23 apparently healthy Chinese women aged 18 to 44 (32±9) y. Spot urine samples were collected on any two days of the week, and 24-h urine samples were collected once every 6 days.

RESULTS

368 spot urine and 230 24-h urine samples were analysed. The median urinary iodine concentration (UIC) was 140.5 (75.2, 246.9) μg/L. The estimated 24-h urinary iodine excretion (24-h UIE) values from spot urine samples and measured 24-h UIE values from 24-h urine samples were 348±240 μg/24h and 330±216 μg/24h (p=0.003), respectively. Irrespective of the urinary iodine method, the intra- individual coefficient of variation (CV%) was lower than the inter-individual CV%. Bland-Altman analysis revealed differences between spot urine and 24-h urine. When the precision ranges with 95% confidence were ±15%, ±20%, ±25% or 30%, the number of an individual's spot urine samples required were 30, 16, 11 or 8, respectively.

CONCLUSIONS

Repeated spot urine is not a feasible way to assess recent individual iodine intake. The development of a multi-indicator system could provide an acceptable individual evaluation index of iodine status.

Systematic analysis of copy-number variations associated with early pregnancy loss

OBJECTIVES

Embryonic numerical and structural chromosomal abnormalities are the most common cause of early pregnancy loss. However, the role of submicroscopic copy-number variations (CNVs) in early pregnancy loss is unclear, and little is known about the critical regions and candidate genes for miscarriage, because of the large size of structural chromosomal abnormalities. The aim of this study was to identify potential miscarriage-associated submicroscopic CNVs and critical regions of large CNVs as well as candidate genes for miscarriage.

METHODS

Over a 5-year period, 5180 fresh miscarriage specimens were investigated using quantitative fluorescent polymerase chain reaction/CNV sequencing or chromosomal microarray analysis. Statistically significant submicroscopic CNVs were identified by comparing the frequency of recurrent submicroscopic CNVs between cases and a published control cohort. Furthermore, genes within critical regions of miscarriage-associated CNVs were prioritized by integrating the Residual Variation Intolerance Score and the human gene expression dataset for identification of potential miscarriage candidate genes.

RESULTS

Results without significant maternal-cell contamination were obtained in 5003 of the 5180 (96.6%) cases. Clinically significant chromosomal abnormalities were identified in 59.1% (2955/5003) of these cases. Three recurrent submicroscopic CNVs (microdeletions in 22q11.21, 2q37.3 and 9p24.3p24.2) were significantly more frequent in miscarriage cases, and were considered to be associated with miscarriage. Moreover, 44 critical regions of large CNVs were observed, including 14 deletions and 30 duplications. There were 309 genes identified as potential miscarriage candidate genes through gene-prioritization analysis.

CONCLUSIONS

We identified potential miscarriage candidate CNVs and genes. These data demonstrate the importance of CNVs in the etiology of miscarriage and highlight the importance of ongoing analysis of CNVs in the study of miscarriage. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

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.

Effects of Iodized Salt and Iodine Supplements on Prenatal and Postnatal Growth: A Systematic Review

Hypothyroidism due to iodine deficiency can impair physical development, most visibly in the marked stunting of myxedematous cretinism caused by severe in utero iodine deficiency. Whether iodine repletion improves growth in noncretinous children is uncertain. Therefore, the aim of our systematic review was to assess the effects of iodine fortification or supplementation on prenatal and postnatal growth outcomes in noncretinous children. Following Cochrane methods and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) reporting guidelines, we searched 10 databases including 2 Chinese databases (latest search February 2017). We included randomized and nonrandomized controlled trials (RCTs; non-RCTs), controlled before-after (CBA) studies, and interrupted time-series studies in pregnant women and children (≤18 y), which compared the effects of iodine (any form, dose, regimen) to placebo, noniodized salt, or no intervention on prenatal and postnatal growth outcomes. We calculated mean differences with 95% CIs, performed random-effects meta-analyses, and assessed the quality of evidence with the use of GRADE (Grading of Recommendations Assessment, Development and Evaluation). We included 18 studies (13 RCTs, 4 non-RCTs, 1 CBA) (n = 5729). Iodine supplementation of severely iodine-deficient pregnant women increased mean birthweight [mean difference (MD): 200 g; 95% CI: 183, 217 g; n = 635; 2 non-RCTs] compared to controls, but the quality of this evidence was assessed as very low. Iodine repletion across the other groups showed no effects on primary growth outcomes (quality of evidence mostly low and very low). Meta-analyses showed a positive effect in moderate-to-mildly iodine-deficient schoolchildren on insulin-like growth factor-1 (MD: 38.48 ng/mL; 95% CI: 6.19, 70.76 ng/mL; n = 498; 2 RCTs, low-quality evidence) and insulin-like growth factor binding protein-3 (MD: 0.46 μg/mL; 95% CI: 0.25, 0.66 μg/mL; n = 498; 2 RCTs, low-quality evidence). In conclusion, we identified few well-designed trials examining the effects of iodine repletion on growth. We are uncertain whether prenatal iodine repletion increases infant growth. Postnatal iodine repletion may improve growth factors but has no clear effects on somatic growth. Our systematic review was registered with PROSPERO as CRD42014012940.

Salt Intake of Lactating Women as Assessed by Modified Food Weighted Records

OBJECTIVE

High salt intake among lactating women can increase the risk of hypertension and cardiovascular disease in infants/offspring. However, considering the limited salt intake data in lactating women, the aims of this study were to compare the salt intake assessed by modified food weighted records (FWR) with that estimated by 24-h urinary sodium excretion and to investigate the salt intake of lactating women.

METHODS

In total, 30 lactating women aged 20-39 years who were 2 to 4 months postpartum were recruited from the cities of Tianjin and Luoyang in China. The household salt intakes of the lactating women were collected by modified FWR for 3 days. Information on the gender, age, eating behaviours and labour intensity of the family members and guests dining at home during the 3 days was recorded. Meanwhile, 24-h urine samples of lactating women were collected.

RESULTS

The salt intakes of the lactating women estimated by modified FWR and 24-h urinary sodium excretion were 8.50 ± 5.32 g/d and 9.34±3.74 g/d (t=-1.29, P=0.207), respectively, which exceeded the WHO recommendation of 5 g/d. There was a significant correlation (r=0.628, P < 0.001) between the salt intakes assessed by the two methods. A Bland-Altman plot showed no significant mean difference between the two methods (salt intake measured by 24-h urinary sodium excretion-salt intake assessed by modified FWR=0.46 g/d, P=0.207).

CONCLUSIONS

The modified FWR is a reliable tool to assess the salt intake of lactating women. The salt intake of lactating women in China remains higher than the WHO recommendation and should be restricted through further efforts.

Universal Salt Iodization Provides Sufficient Dietary Iodine to Achieve Adequate Iodine Nutrition during the First 1000 Days: A Cross-Sectional Multicenter Study

Background

Dietary iodine requirements are high during pregnancy, lactation, and infancy, making women and infants vulnerable to iodine deficiency. Universal salt iodization (USI) has been remarkably successful for preventing iodine deficiency in the general population, but it is uncertain if USI provides adequate iodine intakes during the first 1000 d.

Objective

We set out to assess if USI provides sufficient dietary iodine to meet the iodine requirements and achieve adequate iodine nutrition in all vulnerable population groups.

Methods

We conducted an international, cross-sectional, multicenter study in 3 study sites with mandatory USI legislation. We enrolled 5860 participants from 6 population groups (school-age children, nonpregnant nonlactating women of reproductive age, pregnant women, lactating women, 0-6-mo-old infants, and 7-24-mo-old infants) and assessed iodine status [urinary iodine concentration (UIC)] and thyroid function in Linfen, China (n = 2408), Tuguegarao, the Philippines (n = 2512), and Zagreb, Croatia (n = 940). We analyzed the iodine concentration in household salt, breast milk, drinking water, and cow's milk.

Results

The salt iodine concentration was low (<15 mg/kg) in 2.7%, 33.6%, and 3.1%, adequate (15-40 mg/kg) in 96.3%, 48.4%, and 96.4%, and high (>40 mg/kg) in 1.0%, 18.0%, and 0.5% of household salt samples in Linfen (n = 402), Tuguegarao (n = 1003), and Zagreb (n = 195), respectively. The median UIC showed adequate iodine nutrition in all population groups, except for excessive iodine intake in school-age children in the Philippines and borderline low intake in pregnant women in Croatia.

Conclusions

Salt iodization at ∼25 mg/kg that covers a high proportion of the total amount of salt consumed supplies sufficient dietary iodine to ensure adequate iodine nutrition in all population groups, although intakes may be borderline low during pregnancy. Large variations in salt iodine concentrations increase the risk for both low and high iodine intakes. Strict monitoring of the national salt iodization program is therefore essential for optimal iodine nutrition. This trial was registered at clinicaltrials.gov as NCT02196337.

Breast Milk Iodine Concentration Is a More Accurate Biomarker of Iodine Status Than Urinary Iodine Concentration in Exclusively Breastfeeding Women

Background: Iodine status in populations is usually assessed by the median urinary iodine concentration (UIC). However, iodine is also excreted in breast milk during lactation; thus, breast milk iodine concentration (BMIC) may be a promising biomarker of iodine nutrition in lactating women. Whether the mammary gland can vary fractional uptake of circulating iodine in response to changes in dietary intake is unclear.Objective: We evaluated UIC and BMIC as biomarkers for iodine status in lactating women with a wide range of iodine intakes.Methods: We recruited 866 pairs of lactating mothers and exclusively breastfed infants from 3 iodine-sufficient study sites: Linfen, China (n = 386); Tuguegarao, Philippines (n = 371); and Zagreb, Croatia (n = 109). We also recruited iodine-deficient lactating women from Amizmiz, Morocco (n = 117). We collected urine and breast milk samples and measured UIC and BMIC.Results: In the 3 iodine-sufficient sites, a pooled regression analysis of the estimated iodine excretion revealed higher fractional iodine excretion in breast milk than in urine at borderline low iodine intakes. In contrast, in the iodine-deficient site in Morocco, a constant proportion (∼33%) of total iodine was excreted into breast milk.Conclusions: In iodine-sufficient populations, when iodine intake in lactating women is low, there is increased partitioning of iodine into breast milk. For this reason, maternal UIC alone may not reflect iodine status, and BMIC should also be measured to assess iodine status in lactating women. Our data suggest a BMIC reference range (2.5th and 97.5th percentiles) of 60-465 μg/kg in exclusively breastfeeding women. This trial was registered at clinicaltrials.gov as NCT02196337.

Neonatal thyroid function born to mothers living with long-term excessive iodine intake from drinking water

OBJECTIVE

The effects of long-term excessive maternal iodine intake on neonatal thyroid function are less known. This study aimed to assess the effects of maternal excessive iodine intake from drinking water on thyroid functions of both mothers and their neonates.

DESIGN AND METHODS

This observational study was performed in high iodine (HI) areas and adequate iodine (AI) intake areas, including 384 healthy pregnant women in late gestation (mean week 39·3 ± 1·6 weeks) and their newborns. Blood and urine samples were obtained from pregnant women, while cord blood samples were obtained from neonates. Urinary iodine concentration (UIC) and thyroid function were evaluated.

RESULTS

The median maternal UIC was 1241 and 217 μg/l in HI and AI areas, respectively (P < 0·001). The concentrations of serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) in neonates in HI areas were 7·33 mIU/l (range 5·47, 11·06 mIU/l), 2·93 ± 0·59 and 15·03 ± 1·92 pmol/l, respectively, while that were 4·71 mIU/l (range 3·96, 6·04 mIU/l), 2·31 ± 0·28 and 16·50 ± 1·35 pmol/l in AI neonates (P < 0·05). Similar changes were also observed in neonates in HI areas when excluding the effect of maternal thyroid autoimmunity. Cord blood TSH concentration (r = 0·31, P = 0·001) and FT3 concentration (r = 0·43, P = 0·001) were positively correlated with maternal UIC. Cord blood FT4 concentration was negatively correlated with maternal UIC (r = -0·25, P = 0·001). Mothers living in HI areas (β = 0·296, 95% CI: 0·163, 0·255) and with subclinical hypothyroidism (β = 0·360, 95% CI: 0·034, 0·175) contributed to elevated cord blood TSH concentration in neonates, while male neonates were more likely to present with higher TSH concentration compared with female infants (β = -0·760, 95% CI: -0·119, -0·033).

CONCLUSIONS

Excessive iodine intake during pregnancy was associated with an increased rate of hyperthyrotropinaemia in neonates and their mothers, especially in male neonates.

Systematic review of the effects of iodised salt and iodine supplements on prenatal and postnatal growth: study protocol

INTRODUCTION

Iodine is an essential micronutrient and component of the thyroid hormones. Sufficient ingestion of iodine is necessary for normal growth and development. If iodine requirements are not met, growth can be impaired. Salt iodisation and supplementation with iodine can prevent iodine deficiency disorders and stunted growth. No systematic review has yet collated the evidence linking iodine to growth. With an increased emphasis on stunting within the WHO Global Nutrition Targets for 2025, we propose a systematic review to address this question.

METHODS AND ANALYSIS

We will undertake a systematic review, and if appropriate, meta-analyses, evaluating the effects of iodised salt or iodine supplements on prenatal and postnatal somatic growth, until age 18. We will search a number of databases, including MEDLINE, EMBASE, Web of Science, CINAHL, PsychINFO, the Cochrane Library, including the CENTRAL register of Controlled Trials and also the WHO library and ICTRP (International Clinical Trials Registry Platform), which includes the Clinicaltrials.gov repository. We will also search Wanfang Data and the China Knowledge Resource Integrated Database. Included studies must have compared exposure to iodised salt, iodine supplements or iodised oil, to placebo, non-iodised salt or no intervention. Primary outcomes will be continuous and categorical markers of prenatal and postnatal somatic growth. Secondary outcomes will cover further measures of growth, including growth rates and indirect markers of growth such as insulin-like growth factor-1 (IGF-1).

ETHICS AND DISSEMINATION

The systematic review will be published in a peer-reviewed journal, and will be sent directly to the WHO, United Nations Children's Fund, International Council for the Control of Iodine Deficiency Disorders and other stakeholders. The results generated from this systematic review will provide evidence to support future programme recommendations regarding iodine fortification or supplementation and child growth.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42014012940.

Long-term exposure to excessive iodine from water is associated with thyroid dysfunction in children

Previous studies have indicated an association between iodine excess and increased incidence of thyroid dysfunction in adults. However, there have been few studies on how the intake of excessive iodine affects thyroid function in children. The objective of this study was to assess the effects of a long-term exposure to excessive iodine on thyroid dysfunction in children. Urinary iodine concentration (UIC) and thyroid function in 371 children from a high iodine (HI) area (water iodine: 150-963 μg/L) and 150 children from an adequate iodine (AI) area (water iodine: 12.8-50.9 μg/L) were measured. The water iodine concentration in the HI area was higher than that in the AI area (P < 0.001) and the median urinary iodine concentration of children in the HI area was 1030 μg/L, which was 8.6 times that of children in the AI area (123 μg/L) (P < 0.001). Children in the HI area had a higher concentration of sensitive thyroid stimulating hormone and higher positivity of both thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb). The prevalence of thyroid diseases was higher in HI area children than that in AI area children (P = 0.000), especially subclinical hypothyroidism (SCH; P = 0.004). A body mass index (BMI) of ≥ 22.3 kg/m(2) was associated with the incidence of SCH (OR: 5.51; 95% CI: 1.52, 19.9; P = 0.009). UIC ≥ 600 μg/L (OR: 3.62; 95% CI: 1.22, 10.8; P = 0.024) and TPOAb or TGAb-positivity (Ab+ OR: 6.48; 95% CI: 1.78, 23.6; P = 0.005) in children were significantly and independently associated with SCH. Interactions between UIC ≥ 800 μg/L and Ab+ (P-interaction = 0.004) were found. Furthermore, increased thyroid volume was correlated with higher UIC (β = 0.22; P = 0.002). Excessive iodine intake in children in HI areas is associated with impaired thyroid function; UIC ≥ 600 μg/L and Ab+ are the risk factors for SCH. Effective measures need to be taken for reducing excessive iodine intake.

[Survey on iodine nutrition in high water regions of children, adult and the third trimester pregnant women in China]

OBJECTIVE

To investigate the iodine nutrition status of the susceptible population after stop supplying iodized salt and discuss whether there is iodine nutritional status difference in different populations in high-iodine areas in China.

METHODS

Spot investigation methods were being used, 371 children, 506 adults and 210 cases of pregnant women during the third trimester were selected as respondents. The morning Urine was collected to determinate the urine iodine level. Drinking water was collected to determinate the local water iodine level.

RESULTS

The water iodine level was between 150.3-962.6 microg/L in investigation areas; The median urinary iodine (MUI) of children, adults and pregnant woman was respective 1032.08 microg/L, 1152.01 microg/L and 1240.70 microg/L. Meanwhile 96.2% children and 93.1% adults urine iodine level was more than 300 microg/L and 84.3% of pregnant women urine iodine level was more than 500 microg/L, which belongs to excessive iodine intake. The chi-square test on the distribution of urinary iodine indicate that there is statistical differences in three different population (chi2 = 44.84, P = 0.000). Kruskal-Wallis H test show that the MUI in three different crowd are not all the same (chi2 = 12.83, P = 0.002), when compared by pairs, the difference in MUI between pregnant and children or adults was founded.

CONCLUSION

The iodine nutrition status of children, adult and the third trimester pregnant women in high water regions were iodine excess. The monitor on iodine nutrition status in different peoples should be enhanced. Urinary iodine level of Children can't completely represent the iodine nutritional status of pregnant women, iodine nutritional status monitor standard for pregnant women should be established.

[Thyroid function and serum lipids of adults living in areas of excessive iodine in water in Hebei province]

OBJECTIVE

To investigate the iodine status and the prevalence of thyroid disease and dyslipidemia in adults living in areas of excessive iodine in water in Hebei Province, and to explore the impact of excessive iodine intake on dyslipidemia.

METHODS

Subjects were selected from Haixing County in Cangzhou, Hebei. Fasting morning urine and venous blood were collected to test the levels of urinary iodine and serum free triiodothyronine (FT3), free thyroxine (FT4), and sensitive thyroid-stimulating hormone (sTSH). Thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TGAb) and total cholesterol (CHO), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were also measured.

RESULTS

The median of urinary iodine was 1094.92 (627.38 - 1511.81) microg/L. There were 66 (22.0%) adults diagnosed as thyroid disorder, including 3 (1.0%) hyperthyroidism patients, 7 (2.3%) subclinical hyperthyroidism patients, 12 (4.0%) hypothyroidism patients and 44 (14.7%) subclinical hypothyroidism patients. The levels of CHO, TG, HDL-C and LDL-C were (5.46 +/- 1.06) mmol/L, 2.19 (1.70 - 2.96) mmol/L, 1.18 (1.03 - 1.45) mmol/L and (3.08 +/- 1.05) mmol/L respectively, no significant difference was observed between the thyroid disorder patients or non-patients.

CONCLUSION

The prevalence of dyslipidemia in adults living in areas of excessive iodine in water was high.

Exploration of the safe upper level of iodine intake in euthyroid Chinese adults: a randomized double-blind trial

BACKGROUND

The beneficial health effects associated with Universal Salt Iodization are well known. Yet, little is known about the possible adverse health effects in people with high iodine intake and the safe daily intake upper limit in the Chinese population.

OBJECTIVE

The objective of this study was to explore the safe upper level of total daily iodine intake among adults in China.

DESIGN

A 4-wk, double-blind, placebo-controlled, randomized controlled trial was conducted in 256 euthyroid adults. Participants were randomly assigned to 12 intervention groups with various iodine supplement doses ranging from 0 to 2000 μg/d. Total iodine intake included iodine from both supplements and diet. Multiple outcome measures were used to evaluate possible adverse effects, including thyroid function, thyroid size, and urinary iodine.

RESULTS

The mean iodine intake from the diets and salt intake of the participants were 105 ± 25 and 258 ± 101 μg/d, respectively. In comparison with the placebo group, all iodide-supplemented groups responded with significant increases in median urinary iodine concentrations (P < 0.05) and in thyroid-stimulating hormone concentration (P < 0.05). Thyroid volume decreased after 4 wk in the high-iodine intervention groups (1500-2000 μg). Subclinical hypothyroidism appeared in the groups that received 400 μg I (5%) and 500-2000 μg I (15-47%).

CONCLUSIONS

This study showed that subclinical hypothyroidism appeared in the participants who took the 400-μg I supplement, which provided a total iodine intake of ∼800 μg/d. Thus, we caution against a total daily iodine intake that exceeds 800 μg/d in China and recommend further research to determine a safe daily upper limit.