An assessment of the iodine status and the correlation between iodine nutrition and thyroid function during pregnancy in an iodine sufficient area

Amouzegar, Atieh; Khazan, Marjan; Hedayati, Mehdi; Azizi, Fereidoun

doi:10.1038/ejcn.2013.273

Cited by 24 publications

(17 citation statements)

References 26 publications

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“…In our study, among PW in the countries with sufficient or more-than-adequate iodine intake, no statistically significant correlation was found between Tg and UIC or press.endocrine.org/journal/jcemTSH or TT4, in agreement with previous studies of PW (8,(36)(37)(38)(39). This might result by the iodine-deficient thyroid upregulating thyroid hormone synthesis and maintaining euthyroidism through mechanisms independent of TSH (40,41).…”

Section: Discussionsupporting

confidence: 81%

Dried Blood Spot Thyroglobulin as a Biomarker of Iodine Status in Pregnant Women

Stinca

Andersson

Weibel

et al. 2016

The Journal of Clinical Endocrinology &Amp; Metabolism

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Context: Thyroglobulin (Tg) could be a sensitive biomarker of iodine nutrition in pregnant women (PW). A dried blood spot (DBS) assay would simplify collection and transport in field studies. Objectives: Our aims were to (1) establish and test a reference range for DBS-Tg in PW; (2) determine whether co-measurement of Tg antibodies (Abs) is necessary to define population iodine status. Design, Setting, and Participants: Standardized cross-sectional studies of 3870 PW from 11 countries. For the DBS-Tg reference range, we included TgAb-negative PW (n = 599) from 3 countries with sufficient iodine intake. Main Outcome Measures: We measured the urinary iodine concentration and DBS thyroidstimulating hormone, total thyroxin, Tg, and TgAb. Results: In the reference population, the median DBS-Tg was 9.2 g/L (95% confidence interval, 8.7 to 9.8 g/L) and was not significantly different among trimesters. The reference range was 0.3 to 43.5 g/L. Over a range of iodine intake, the Tg concentrations were U-shaped. Within countries, the median DBS-Tg and the presence of elevated DBS-Tg did not differ significantly between all PW and PW who were TgAb-negative. Conclusions: A median DBS-Tg of 10 g/L with <3% of values 44 g/L indicated population iodine sufficiency. Concurrent measurement of TgAb did not appear necessary to assess the population iodine status.

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Section: Discussionsupporting

confidence: 81%

Dried Blood Spot Thyroglobulin as a Biomarker of Iodine Status in Pregnant Women

Stinca

Andersson

Weibel

et al. 2016

The Journal of Clinical Endocrinology &Amp; Metabolism

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“…26 In this study, although T3 was higher in both deficient and mildly deficient women compared with sufficient women, there were no differences in T3/T4 ratio between the groups. Several studies report no associations between maternal UIC and thyroid function, 21 , 27 , 28 and in a study comparable to the present, 29 no associations between UIC and repeated measures of THs were found. However, that study population were classified as iodine sufficient (median UIC 160 μg/l in second trimester), hence, the influence on thyroid function by severity and timing of iodine deficiency vary between study populations and can explain discrepancies between study results.…”

Section: Discussionsupporting

confidence: 69%

Thyroid homeostasis in mother–child pairs in relation to maternal iodine status: the MISA study

et al. 2017

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Background/Objectives:Iodine deficiency during pregnancy may influence maternal and foetal thyroid function with the risk of causing neurocognitive and psychomotor deficits in the offspring. The objective of this study was to assess iodine status in pregnant women from Northern Norway and to investigate the influence of iodine status on maternal and infant thyroid function.Subjects/Methods:Women from the Northern Norway Mother-and-Child contaminant Cohort Study (MISA) donated a blood and urine sample at three visits during their pregnancy and postpartum period (in second trimester, 3 days and 6 weeks after delivery. N=197). Women were assigned to iodine status groups according to urine iodine concentrations (UICs) in second trimester and mixed effects linear models were used to investigate potential associations between iodine status and repeated measurements of thyroid-stimulating hormone (TSH), thyroid hormones (THs), TH-binding proteins and thyroid peroxidase antibodies. Associations between maternal iodine status and TSH in heel prick samples from the infants were investigated with linear regression.Results:Median UIC in second trimester was 84 μg/l (range 18–522) and 80% had UIC below recommended level (<150 μg/l). Iodine-deficient women had higher concentrations of T3, FT3 and FT4 (estimated differences (confidence intervals) of 0.10 nmol/l (0.01, 0.17), 0.16 pmol/l (0.05, 0.26) and 0.45 pmol/l (0.10, 0.78), respectively) compared with iodine-sufficient women. The concentrations varied within normal reference ranges, but the majority of women with subclinical hypothyroidism were iodine deficient. Maternal iodine status did not influence infant TSH concentrations.Conclusions:This study indicate iodine deficiency among pregnant women in Norway. Iodine status during pregnancy influences maternal thyroid homeostasis and is therefore a risk factor for foetal and infant development.

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“…For example, Kim et al found that the 24-h urinary iodine excretion correlated more strongly with the iodine:creatinine ratio rather than with the simple UIC [36] . Other authors discourage the use of the iodine:creatinine ratio because of its higher variability [2,35] . Our results are consistent with the latter observation and fail to give evidence of a substantial advantage in normalization to urine creatinine levels.…”

Section: Discussionmentioning

confidence: 98%

“…Iodine is the major component of thyroid hormones and neurodevelopment of the fetus and breast-fed infants are crucially affected by maternal iodine intake [1,2] . The key indicator of population iodine nutrition recommended by the World Health Organization (WHO) is represented by the median concentration of UIC measured by a 24-h collection (gold standard) or by more practical single spot samples [2 -5] : a median UIC of at least 100 μ g/L represents an adequate iodine nutrition in a population and UIC equal to 300 μ g/L was set as upper normal limit [3] .…”

Section: Introductionmentioning

confidence: 99%

Potentiometric measurement of urinary iodine concentration in patients with thyroid diseases with and without previous exposure to non-radioactive iodine

Giovacchini¹,

Giovanella²,

Haldemann³

et al. 2015

Clinical Chemistry and Laboratory Medicine (CCLM)

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An assessment of the iodine status and the correlation between iodine nutrition and thyroid function during pregnancy in an iodine sufficient area

Abstract: In our cohort of pregnant women the iodine intakes were sufficient, and no correlation between urinary iodine concentration and thyroid function tests was found.

Cited by 24 publications

References 26 publications

Dried Blood Spot Thyroglobulin as a Biomarker of Iodine Status in Pregnant Women

Dried Blood Spot Thyroglobulin as a Biomarker of Iodine Status in Pregnant Women

Thyroid homeostasis in mother–child pairs in relation to maternal iodine status: the MISA study

Potentiometric measurement of urinary iodine concentration in patients with thyroid diseases with and without previous exposure to non-radioactive iodine

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