Pregnant women at risk for iodine deficiency but adequate iodine intake in school-aged children of Zhejiang Province, China.

The median urinary iodine concentration (UIC) of school-aged children has been commonly used as a surrogate to assess iodine status of a population including pregnant women. However, pregnant women have higher iodine requirements than children due to increased production of thyroid hormones. The aim of the study was to evaluate the iodine status of pregnant women and children as well as their household salt iodine concentration (SIC) in Quzhou, Zhejiang Province, China. Eligible pregnant women and children from all six counties of Quzhou in 2021 were recruited into the study. They were asked to complete a socio-demographic questionnaire and provide both a spot urine and a household table salt sample for the determination of UIC and SIC. A total of 629 pregnant women (mean age and gestation weeks of 29.6 years and 21.6 weeks, respectively) and 1273 school-aged children (mean age of 9 years and 49.8% of them were females) were included in the study. The overall median UIC of pregnant women and children in our sample was 127 (82, 193) µg/L and 222 (147, 327) µg/L, respectively, indicating sufficient iodine status in children but a risk of mild-to-moderate iodine deficiency in pregnant women. Distribution of iodine nutrition in children varied significantly according to their sex and age (P < 0.05). The rate of adequately household iodised salt samples (18-33 mg/kg) provided by pregnant women and children was 92.4% and 90.6%, respectively. In conclusion, our results indicated a risk of insufficient iodine status in pregnant population of China, but iodine sufficiency in school-aged children. Our data also suggested that median UIC of children may not be used as a surrogate to assess iodine status in pregnant women.

Iodine Nutrition, Thyroid-stimulating Hormone, and Related Factors of Postpartum Women from three Different Areas in China: A Cross-sectional Survey.

Objective: Studies on the relationship between iodine, vitamin A (VA), and vitamin D (VD) and thyroid function are limited. This study aimed to analyze iodine and thyroid-stimulating hormone (TSH) status and their possible relationships with VA, VD, and other factors in postpartum women. Methods: A total of 1,311 mothers (896 lactating and 415 non-lactating) from Hebei, Zhejiang, and Guangxi provinces were included in this study. The urinary iodine concentration (UIC), TSH, VA, and VD were measured. Results: The median UIC of total and lactating participants were 142.00 µg/L and 139.95 µg/L, respectively. The median TSH, VA, and VD levels in all the participants were 1.89 mIU/L, 0.44 µg/mL, and 24.04 ng/mL, respectively. No differences in the UIC were found between lactating and non-lactating mothers. UIC and TSH levels were significantly different among the three provinces. The rural UIC was higher than the urban UIC. Obese mothers had a higher UIC and a higher prevalence of excessive TSH. Higher UICs and TSHs levels were observed in both the VD deficiency and insufficiency groups than in the VD-sufficient group. After adjustment, no linear correlation was observed between UIC and VA/VD. No interaction was found between vitamins A/D and UIC on TSH levels. Conclusion: The mothers in the present study had no iodine deficiency. Region, area type, BMI, and VD may be related to the iodine status or TSH levels.

National and Sub-National Estimates of Household Coverage of Iodized Salt and Urinary Iodine Status among Women of Reproductive Age in India: Insights from the India Iodine Survey, 2018-19.

BACKGROUND: Iodine deficiency is a significant public health problem for many populations worldwide, including India, particularly during the "first 1000 days" of life. Though Universal Salt iodization (USI) is mandatory in India, prior to 2018-19, there was no state-wide survey with estimates of iodine concentrations in salt using iodometric titration. Taking cognizance of this fact, Nutrition International commissioned the first-of-its-kind national-level survey in India, titled the India Iodine Survey 2018-19. OBJECTIVES: The study was conducted across the country to provide national and subnational estimates of iodine concentrations in household salt using iodometric titration and iodine nutrition status among women of reproductive age (15-49 y). METHODS: The survey adopted a multi-stage randomcluster probability proportional to size sampling design, covering 21,406 households in all the states and union territories (UTs) of India. RESULTS: At the national level, the household coverage of edible salt with adequate iodine (content ≥15 parts/million) was 76.3%. At the sub-national level, the coverage varied, with 10 states and 3 UTs achieving USI and 11 states and 2 UTs falling below the national average, with the highest among all the states and UTs, being Jammu and Kashmir and the lowest being Tamil Nadu. At the national level, the median urinary iodine concentration for pregnant women was 173.4 µg/L, for lactating women was 172.8 µg/L, and for non-pregnant, non-lactating women, it was 178.0 µg/L, which is within the adequate iodine nutrition range according to the WHO guidelines. CONCLUSIONS: The survey results can be widely used by various stakeholders, including government, academia, and industry, to understand the iodine nutrition status of the population, enable the scale-up of sustained efforts toward consolidating gains and achieving USI, leading to the reduction and elimination of Iodine Deficiency Disorders.

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.

Assessment of thyroid function in children, adults and pregnant and lactating women after long-term salt iodisation measurements.

Universal salt iodisation (USI) has been successfully implemented in China for more than 15 years. Recent evidence suggests that the definition of 'adequate iodine' (100-199 µg/l) be revised to 'sufficient iodine' (100-299 µg/l) based on the median urinary iodine concentration (MUI) in school-age children. The objective of this study was to determine the prevalence of thyroid dysfunction in populations after long-term salt iodisation and examine whether the definition of adequate iodine can be broadened to sufficient iodine based on the thyroid function in four population groups. A cross-sectional survey was conducted in six provinces in the northern, central and southern regions of China. Four population groups consisting of 657 children, 755 adults, 347 pregnant women and 348 lactating women were recruited. Three spot urinary samples were collected over a 10-d period and blood samples were collected on the 1st day. In the study, among the adults, pregnant women and lactating women, the prevalence rates of elevated thyroglobulin antibody and thyroid microsomal antibody levels were 12·4, 8·5 and 7·8 %, and 12·1, 9·1 and 9·1 %, respectively. Abnormally high thyroid dysfunction prevalence was not observed after more than 15 years of USI in China because the thyroid dysfunction rates were all <5 %. The recommended range should be cautiously broadened from adequate iodine to sufficient iodine according to the MUI of school-age children considering the high levels of hormones and antibodies in the other populations. Adults, particularly pregnant women positive for thyroid antibodies, should be closely monitored.

Iodine Deficiency Disorder and Goitre among School Children in Sarawak -A Nationwide Study

Iodine deficiency disorders (IDD), is one of the most important micronutrient deficiencies which has multiple adverse effects on growth and development. The aim of this study was to determine the prevalence of IDD among school children and to elucidate the distribution of iodized salt at household level in Sarawak, East Malaysia. This cross-sectional study was conducted among school children aged 8 to 10 years in 2008. A multi-stage probability proportionate to population size (PPS) cluster sampling method was used to obtain a representative state sample of 1200 school children. Spot urine samples were collected for the determination of urinary iodine concentration while the iodine content in salt was determined using field rapid test kits. The thyroid status was determined by palpation. Response rate was 92.0% (n=1104/1200). The prevalence of goitre among school children in Sarawak was 2.9% (5.2% in urban, 0.7% in rural). The median urinary iodine concentration (UIC) among the school children was 102.1 µg/L (IQR, 62.3-146.5 µg/L). Urban children had significantly higher median UIC of 109.3 µg/L (IQR, 72.4-159.0 µg/L) than their rural counterparts [91.9 µg/L (IQR, 55.7-140.2 µg/L)]. The salt samples tested by rapid test kit (RTK) showed only 46.0% of household salt contained iodine. The present study revealed that the population in Sarawak were of borderline iodine sufficient with mild IDD seen in rural areas. Hence, the state IDD control programmes need to encourage and advocate the consumption of iodized salt in order to eliminate IDD-related health problems in Sarawak.