Dataset Information

Urinary iodine concentration identifies pregnant women as iodine deficient yet school-aged children as iodine sufficient in rural Niger.

ABSTRACT:

Objective

To assess iodine status among pregnant women in rural Zinder, Niger and to compare their status with the iodine status of school-aged children from the same households.

Design

Seventy-three villages in the catchment area of sixteen health centres were randomly selected to participate in the cross-sectional survey.

Setting

Salt iodization is mandatory in Niger, requiring 20-60 ppm iodine at the retail level.

Subjects

A spot urine sample was collected from randomly selected pregnant women (n 662) and one school-aged child from the same household (n 373). Urinary iodine concentration (UIC) was assessed as an indicator of iodine status in both groups. Dried blood spots (DBS) were collected from venous blood samples of pregnant women and thyroglobulin (Tg), thyroid-stimulating hormone and total thyroxine were measured. Iodine content of household salt samples (n 108) was assessed by titration.

Results

Median iodine content of salt samples was 5·5 ppm (range 0-41 ppm), 98 % had an iodine content 40 µg/l.

Conclusions

In this region of Niger, most salt is inadequately iodized. UIC in pregnant women indicated iodine deficiency, whereas UIC of school-aged children indicated marginally adequate iodine status. Thus, estimating population iodine status based solely on monitoring of UIC among school-aged children may underestimate the risk of iodine deficiency in pregnant women.

SUBMITTER: Hess SY

PROVIDER: S-EPMC10261634 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Publications

Urinary iodine concentration identifies pregnant women as iodine deficient yet school-aged children as iodine sufficient in rural Niger.

Hess Sonja Y SY Ouédraogo Césaire T CT Young Rebecca R RR Bamba Ibrahim F IF Stinca Sara S Zimmermann Michael B MB Wessells K Ryan KR

Public health nutrition 20161215 7

<h4>Objective</h4>To assess iodine status among pregnant women in rural Zinder, Niger and to compare their status with the iodine status of school-aged children from the same households.<h4>Design</h4>Seventy-three villages in the catchment area of sixteen health centres were randomly selected to participate in the cross-sectional survey.<h4>Setting</h4>Salt iodization is mandatory in Niger, requiring 20-60 ppm iodine at the retail level.<h4>Subjects</h4>A spot urine sample was collected from ra ...[more]

PMID: 27974077

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Project description:BackgroundIodine deficiency is a public health problem. The universal salt iodization (USI) program is the main, simple, and cost-effective intervention strategy to control iodine deficiency. The study examined the iodine status in school-aged children in Ashanti region, Ghana, using thyroid volumes along with urinary iodine concentrations, the methods recommended by the WHO/ICCIDD for monitoring the sustained impact of USI programs.MethodsThis cross-sectional study was conducted among school-aged children (6-12 years) from randomly selected schools in the central and northern part of the Ashanti region, Kumasi Metropolis, and Ejura-Sekyedumase Municipality, respectively. A total of 852 children were enrolled in the study. Thyroid volume and urinary iodine concentrations of the children were determined using the standardized methods recommended by WHO/ICCIDD. Anthropometric measurements were also evaluated.ResultsThe mean values of thyroid volume in female and male school-aged children were 3.53 ± 0.09 and 3.32 ± 0.07, respectively. The thyroid size was significantly associated with age (P < 0.0001), weight (P < 0.0001), height (P < 0.0001), BMI (P < 0.05), and BSA (P < 0.0001) by Pearson's correlation in both males and females. The P50 (median) thyroid volumes of school children investigated in this study were generally larger compared to the WHO/ICCIDD reference data by age and body surface area. The median value of urinary iodine concentration was 201.85 μg/L, which showed significant sex difference (P value <0.0001). Excessive iodine nutrition (≥300 μg/L) was observed among 34.4% of male children and 27.6% of female children. Also, 12.8% of the male and 19.5% of the female children had UIC below requirement (<100 μg/L). The criteria of thyroid volume per age yielded a goitre prevalence of 2.2%. In contrast, the criteria of thyroid volume by body surface area yielded a goitre prevalence of 0.9%.ConclusionThe study clearly indicated that adequate iodine nutrition exists generally among the school children. However, insufficient and excessive iodine intakes still persist among some of the children. The establishment of local reference values for thyroid volume that might be applicable to precisely define goitre prevalence in the Ghanaian context is highly recommended.

Project description:ObjectiveReports from populations with an insufficient iodine intake suggest that children of mothers with mild iodine deficiency during pregnancy are at risk for cognitive impairments. However, it is unknown whether, even in iodine-sufficient areas, low levels of iodine intake occur that influence cognitive development in the offspring. This study investigated the association between maternal low urinary iodine concentration (UIC) in pregnancy and children's cognition in a population-based sample from a country with an optimal iodine status (the Netherlands).Setting and participantsIn 1525 mother-child pairs in a Dutch multiethnic birth cohort, we investigated the relation between maternal UIC<150 μg/g creatinine, assessed <18 weeks gestation and children's cognition.Outcomes measuresNon-verbal IQ and language comprehension were assessed during a visit to the research centre using Dutch test batteries when the children were 6 years.ResultsIn total, 188 (12.3%) pregnant women had UIC<150 μg/g creatinine, with a median UIC equal to 119.3 μg/g creatinine. The median UIC in the group with UIC>150 μg/g creatinine was 322.9 μg/g and in the whole sample 296.5 μg/g creatinine. There was a univariate association between maternal low UIC and children's suboptimum non-verbal IQ (unadjusted OR=1.44, 95% CI 1.02 to 2.02). However, after adjustment for confounders, maternal low UIC was not associated with children's non-verbal IQ (adjusted OR=1.33, 95% CI 0.92 to 1.93). There was no relation between maternal UIC in early pregnancy and children's language comprehension at 6 years.ConclusionsThe lack of a clear association between maternal low UIC and children's cognition probably reflects that low levels of iodine were not frequent and severe enough to affect neurodevelopment. This may result from the Dutch iodine fortification policy, which allows iodised salt to be added to almost all processed food and emphasises the monitoring of iodine intake in the population.

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

Project description:BACKGROUND:Studies indicate that mild to moderate iodine deficiency in pregnancy may have a long-term negative impact on child neurodevelopment. These effects are likely mediated via changes in maternal thyroid function, since iodine is essential for the production of thyroid hormones. However, the impact of iodine availability on thyroid function during pregnancy and on thyroid function reference ranges are understudied. The aim of this study was to investigate the association between iodine intake and thyroid function during pregnancy. DESIGN:In a population-based pregnancy cohort including 2910 pregnant women participating in The Norwegian Mother and Child Cohort Study, we explored cross sectional associations of maternal iodine intake measured (1) by a food frequency questionnaire and (2) as iodine concentration in a spot urine sample, with plasma thyroid hormones and antibodies. RESULTS:Biological samples were collected in mean gestational week 18.5 (standard deviation 1.3) and diet was assessed in gestational week 22. Median iodine intake from food was 121 μg/day (interquartile range 90, 160), and 40% reported use of iodine-containing supplements in pregnancy. Median urinary iodine concentration (UIC) was 59 μg/L among those who did not use supplements and 98 μg/L in the women reporting current use at the time of sampling, indicating mild to moderate iodine deficiency in both groups. Iodine intake as measured by the food frequency questionnaire was not associated with the outcome measures, while UIC was inversely associated with FT3 (p = 0.002) and FT4 (p < 0.001). Introduction of an iodine-containing supplement after gestational week 12 was associated with indications of lower thyroid hormone production (lower FT4, p = 0.027, and nonsignificantly lower FT3, p = 0.17). The 2.5th and 97.5th percentiles of TSH, FT4, and FT3 were not significantly different by groups defined by calculated iodine intake or by UIC. CONCLUSION:The results indicate that mild to moderate iodine deficiency affect thyroid function in pregnancy. However, the differences were small, suggesting that normal reference ranges can be determined based on data also from mildly iodine deficient populations, but this needs to be further studied. Introducing an iodine-containing supplement might temporarily inhibit thyroid hormone production and/or release.

Dataset Information

Urinary iodine concentration identifies pregnant women as iodine deficient yet school-aged children as iodine sufficient in rural Niger.

Objective

Design

Setting

Subjects

Results

Conclusions

Publications

Urinary iodine concentration identifies pregnant women as iodine deficient yet school-aged children as iodine sufficient in rural Niger.

Similar Datasets

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