U-Shaped Associations between Urinary Iodine Concentration and the Prevalence of Metabolic Disorders: A Cross-Sectional Study

Mild to moderate iodine deficiency is common among women of childbearing age. Data on iodine status in infants are sparse, partly due to the challenges in collecting urine. Urinary iodine concentration (UIC) is considered a good marker for recent dietary iodine intake and status in populations. The aim of this study was to investigate the reliability of iodine concentration measured in two spot-samples from the same day of diaper-retrieved infant urine and in their mothers’ breastmilk. We collected urine and breastmilk from a sample of 27 infants and 25 mothers participating in a cross-sectional study at two public healthcare clinics in Norway. The reliability of iodine concentration was assessed by calculating the intraclass correlation coefficients (ICC) and the coefficient of variation (CV). The ICC for infants’ urine was 0.64 (95% confidence interval (CI) 0.36–0.82), while the ICC for breastmilk was 0.83 (95% CI 0.65–0.92) Similarly, the intraindividual CV for UIC was 0.25 and 0.14 for breastmilk iodine concentration (BIC). Compared to standard methods of collecting urine for measuring iodine concentration, the diaper-pad collection method does not substantially affect the reliability of the measurements.

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Factors Associated with Urinary Iodine Concentration among Women of Reproductive Age, 20–49 Years Old, in Tanzania: A Population-Based Cross-Sectional Study

Current Developments in Nutrition ◽

10.1093/cdn/nzaa079 ◽

2020 ◽

Vol 4 (5) ◽

Author(s):

Djibril M Ba ◽

Paddy Ssentongo ◽

Muzi Na ◽

Kristen H Kjerulff ◽

Guodong Liu ◽

...

Keyword(s):

Urinary Iodine ◽

Iodine Concentration ◽

Population Based ◽

Cross Sectional Study ◽

Iodized Salt ◽

Reproductive Age ◽

Urinary Iodine Concentration ◽

Women Of Reproductive Age ◽

Cross Sectional ◽

Factors Associated

ABSTRACT Background Universal salt iodization (USI) is the most feasible and cost-effective, and equitable, approach to prevent iodine deficiency. Severe maternal iodine deficiency during pregnancy is associated with serious adverse gestational and birth outcomes. Objectives The aim was to assess iodine status and identify independent factors associated with urinary iodine concentration (UIC) among women of reproductive age in Tanzania. Methods This was a weighted, population-based, cross-sectional study in 2985 women of reproductive age (20–49 y) in Tanzania who participated in the Demographic and Health Surveys in 2015–2016 (DHS 2015–2016) and had measured UIC. Multivariable generalized linear regression was used to identify potential factors that were associated with UIC. Results The median UICs among women consuming inadequately iodized salt (93.6 μg/L; 25th and 75th percentiles: 43.1, 197.9 μg/L) and women in the lowest socioeconomic status (92.3 μg/L; 45.6, 194.4 μg/L) were below the WHO-recommended ranges (≥150 μg/L for pregnant women and ≥100 μg/L for nonpregnant women). The results of multivariable models indicated that pregnant women had 1.21 μg/L lower UIC than nonpregnant women (β = −1.21; 95% CI: −3.42, −0.12), breastfeeding women had 1.02 μg/L lower UIC than nonbreastfeeding women (β = −1.02; 95% CI: −2.25, −0.27), and women with no education had a 1.88 μg/L lower UIC compared with those with secondary/highest education (β = −1.88; 95% CI: −4.58, −0.36). Women consuming inadequately iodized salt had 6.55 μg/L lower UIC than those consuming adequately iodized salt (β = −6.55; 95% CI: −9.24, −4.33). The median UIC varied substantially across geographic zones, ranging from 83.2 μg/L (45.9, 165.3) in the Western region to 347.8 μg/L (185.0, 479.8) in the Eastern region. Conclusions Our findings indicated a great heterogeneity in median UIC across regions of Tanzania among women of reproductive age. Poverty, consuming inadequately iodized salt, and lack of education appeared to be the driving factors for lower UIC in Tanzania.

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The Effect of Iodine Status on the Risk of Thyroid Nodules: A Cross-Sectional Study in Zhejiang, China

International Journal of Endocrinology ◽

10.1155/2020/3760375 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Xiaoming Lou ◽

Xiaofeng Wang ◽

Zhifang Wang ◽

Guangming Mao ◽

Wenming Zhu ◽

...

Keyword(s):

Thyroid Nodules ◽

Adult Population ◽

Urinary Iodine ◽

Cross Sectional Study ◽

Urinary Iodine Concentration ◽

Sectional Study ◽

Percent Reduction ◽

Iodine Nutrition ◽

Cross Sectional ◽

Significant Difference

Objective. The aim of this study was to explore whether iodine nutrition is associated with the risk of thyroid nodules among adult population in Zhejiang Province, China. Methods. A cross-sectional study was conducted in the general population aged 18 years or older. A total of 2,710 subjects received physical examination, questionnaires, and thyroid ultrasonography. Urinary iodine concentration (UIC) and thyroid hormone levels were measured and documented for each subject. 4 multiple logistic regression models adjusted for other risk factors were applied to analyze the association between iodine nutrition and thyroid nodules. Results. The prevalence of thyroid nodules was 15.5% among all adults. As indicated by all 4 models, subjects with UIC varying from 200 μg l−1 to 399 μg l−1 had lower risk of thyroid nodules compared with those with relatively low UIC (<100 μg l−1), with approximately 37–57 percent reduction in risk. Moreover, subjects with UIC between 100 and 199 μg l−1 had a decreased risk of thyroid nodules in model 1 and 2 (OR = 0.75, 95% CI, 0.58–0.97; OR = 0.75, 95% CI, 0.58–0.97, respectively). However, there was no significant difference of risk in thyroid nodules between subjects with high UIC (≥400 μg l−1) and low UIC (<100 μg l−1). Furthermore, intake of iodized salt was inversely associated with risk of thyroid nodules, with approximately 69–77 percent reduction in risk. Conclusion. The relationship between UIC and the risk of thyroid nodules is U-shaped. Consumption of noniodized salt is an independent risk factor of thyroid nodules.

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Saliva Iodine Concentration in Children and Its Association with Iodine Status and Thyroid Function

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/clinem/dgaa471 ◽

2020 ◽

Vol 105 (9) ◽

pp. e3451-e3459 ◽

Cited By ~ 1

Author(s):

Wenxing Guo ◽

Ziyun Pan ◽

Ying Zhang ◽

Ya Jin ◽

Shuyao Dong ◽

...

Keyword(s):

Thyroid Function ◽

Primary Schools ◽

Urinary Iodine ◽

Reference Value ◽

Iodine Concentration ◽

Cross Sectional Study ◽

Urinary Iodine Excretion ◽

Urinary Iodine Concentration ◽

Cross Sectional ◽

Iodine Status

Abstract Context The effectiveness of saliva iodine concentration (SIC) in evaluating iodine status in children is not clear. Objective We aimed to explore associations between SIC and assessed indicators of iodine status and thyroid function. Design Cross-sectional study. Setting Primary schools in Shandong, China. Participants Local children aged 8 to 13 years with no known thyroid disease were recruited to this study. Main outcome measures Blood, saliva, and urine samples were collected to evaluate thyroid function and iodine status. Results SIC positively correlated with spot urinary iodine concentration (r = 0.29, P < 0.0001), 24-hour urinary iodine concentration (r = 0.35, P < 0.0001), and 24-hour urinary iodine excretion (r = 0.40, P < 0.0001). The prevalence of thyroid nodules (TN) and goiter showed an upward trend with SIC quantiles (P for trend < 0.05). Children with SIC <105 μg/L had a higher risk of insufficient iodine status (OR = 4.18; 95% CI, 2.67-6.56) compared with those with higher SIC. Those having SIC >273 μg/L were associated with greater risks of TN (OR = 2.70; 95% CI, 1.38-5.26) and excessive iodine status (OR = 18.56; 95% CI, 5.66-60.91) than those with lower SIC values. Conclusions There is a good correlation between SIC and urinary iodine concentrations. It is of significant reference value for the diagnosis of iodine deficiency with SIC of less than 105 μg/L and for the diagnosis of iodine excess and TN with SIC of more than 273 μg/L. Given the sanitary nature and convenience of saliva iodine collection, SIC is highly recommended as a good biomarker of recent iodine status in school-aged children.

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