Neonatal TSH levels in Northern Ireland from 2003 to 2014 as a measure of population iodine status

Mullan, Karen; Patterson, Chris; Doolan, K.; Cundick, J.; Hamill, Louise; McKeeman, G; McMullan, Paul; Smyth, P. P. A.; Woodside, Jayne V.

doi:10.1111/cen.13849

Cited by 5 publications

(7 citation statements)

References 31 publications

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“…In several other countries nTSH was used to assess the population’s iodine status as well. Our results are similar to Northern Ireland with an overall proportion of 0.49% with nTSH > 5 mIU/L in 2003-2014 [ 30 ]. But higher proportions were observed in Belgium 2.6-3.3% in 2009-2011 [ 9 ], Australia 4.1-9.7% in 2001-2006 [ 31 ], Germany 14% in 2005-2006 [ 32 ], and Latvia 8.4-16.5% in 2000-2002 [ 33 ].…”

Section: Discussionsupporting

confidence: 86%

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Neonatal heel prick screening TSH concentration in the Netherlands as indicator of iodine status

Verkaik-Kloosterman

2021

Nutr J

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Background Neonatal Thyroid Stimulating Hormone (nTSH) is proposed as indicator of iodine deficiency in a population. Population’s iodine sufficiency is indicated by a proportion of the newborns less than 3% having nTSH above 5 mIU/L. The aim of this study was to explore the Dutch neonatal heel prick screening TSH data to assess iodine status in the Netherlands and identify determinants and potential confounders of this assessment. Methods All newborns born in the Netherlands between 2007 and 2015 with a heel prick collection at day 3-7 were included (n = 1,435,600), except preterm neonates and baby’s with a low birth weight. Total T4 was measured for all children, nTSH was measured in the ~ 20% children with lowest total T4. Results The proportion with nTSH > 5mIU/L fluctuated between 0.6-1.3% in 2007-2015. nTSH was significantly associated with laboratory performing the nTSH assay and age of heel prick sampling. The overall increasing trend in proportion nTSH >1mIU/L was confounded by the laboratories with different and changed assays. Conclusions The low proportion neonates with high nTSH suggests a sufficient iodine status in the Netherlands. Whether the increased proportion nTSH>1mIU/L over the years is an early indicator of deterioration of the iodine status remains unclear, due to differences and changes in analytical assays. nTSH might be a valuable and inexpensive way to get crude insight in the (trend in) iodine status, but more research is needed on the validity and potential conditions.

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Section: Discussionsupporting

confidence: 86%

“…In our study the proportion children with nTSH > 2 mIU/L ranged in 2007-2015 from 7.6-11.3%. The proportions found in cohorts in Northern Ireland (6.2%) [ 30 ] and Wales UK (10.9-11.9%) [ 37 ] are similar. Higher proportions were observed in Belgium (21-40%) [ 9 ].…”

Section: Discussionmentioning

confidence: 94%

Neonatal heel prick screening TSH concentration in the Netherlands as indicator of iodine status

Verkaik-Kloosterman

2021

Nutr J

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“…Several studies suggest the current TSH threshold for mildly elevated TSH may be too high to identify populations exposed to mild iodine deficiency ( 334-337 ). Still, trends in neonatal TSH over time in mildly deficient populations may reflect changes in iodine status ( 333 , 334 , 336 , 337 ). Studies evaluating the association between neonatal TSH and UIC just after birth ( 338 , 339 ) are difficult to interpret because UIC obtained just after birth is unreliable.…”

Section: Biomarkers Of Iodine Statusmentioning

confidence: 99%

The Role of Iodine for Thyroid Function in Lactating Women and Infants

Andersson

2021

Endocrine Reviews

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Iodine is a micronutrient needed for the production of thyroid hormones, which regulate metabolism, growth, and development. Iodine deficiency or excess may alter the thyroid hormone synthesis. The potential effects on infant development depend on the degree, timing, and duration of exposure. The iodine requirement is particularly high during infancy because of elevated thyroid hormone turnover. Breastfed infants rely on iodine provided by human milk, but the iodine concentration in breast milk is determined by the maternal iodine intake. Diets in many countries cannot provide sufficient iodine, and deficiency is prevented by iodine fortification of salt. However, the coverage of iodized salt varies between countries. Epidemiological data suggest large differences in the iodine intake in lactating women, infants, and toddlers worldwide, ranging from deficient to excessive intake. In this review, we provide an overview of the current knowledge and recent advances in the understanding of iodine nutrition and its association with thyroid function in lactating women, infants, and toddlers. We discuss risk factors for iodine malnutrition and the impact of targeted intervention strategies on these vulnerable population groups. We highlight the importance of appropriate definitions of optimal iodine nutrition and the need for more data assessing the risk of mild iodine deficiency for thyroid disorders during the first 2 years in life.

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“…The severity, (mild, moderate and severe) is further defined by the proportion of neonates with TSH concentrations greater than 5 mIU/L. There has been a large body of literature reporting iodine deficiency status or outcomes of iodine prophylaxis programs using nTSH results, with reference to the WHO criteria [32], and in more recent literature [33,34,35,36,37,38]. Most published reports have employed dried capillary blood spots from heel-prick as recommended.…”

Section: Methods For Measuring and Assessing Iodine Nutritionmentioning

confidence: 99%

“…Although this indicator has been widely used for several decades to assess a population’s iodine nutrition status and accepted at its face value, many factors can influence the results. These include maternal smoking and lower weight gain during pregnancy [39], mode of delivery [32], birth weight of the child [33,40], days after birth of sample collection [32,33,34,41], assay methodologies [32] and seasonal variations [33,37]. Further, several studies suggest the proposed cut-off for iodine deficiency should be re-evaluated.…”

Section: Methods For Measuring and Assessing Iodine Nutritionmentioning

confidence: 99%

Optimal Assessment and Quantification of Iodine Nutrition in Pregnancy and Lactation: Laboratory and Clinical Methods, Controversies and Future Directions

Eastman

2019

Nutrients

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Iodine intake must be boosted during pregnancy to meet the demands for increased production and placental transfer of thyroid hormone essential for optimal foetal development. Failure to meet this challenge results in irreversible brain damage, manifested in severity from neurological cretinism to minor or subtle deficits of intelligence and behavioural disorders. Attention is now being focused on explaining observational studies of an association between insufficient iodine intake during pregnancy and mild degrees of intellectual impairment in the offspring and confirming a cause and effect relationship with impaired maternal thyroid function. The current qualitative categorisation of iodine deficiency into mild, moderate and severe by the measurement of the median urinary iodine concentration (MUIC) in a population of school-age children, as a proxy measure of dietary iodine intake, is inappropriate for defining the degree or severity of gestational iodine deficiency and needs to be replaced. This review examines progress in analytical techniques for the measurement of urinary iodine concentration and the application of this technology to epidemiological studies of iodine deficiency with a focus on gestational iodine deficiency. We recommend that more precise definitions and measurements of gestational iodine deficiency, beyond a spot UIC, need to be developed. We review the evidence for hypothyroxinaemia as the cause of intrauterine foetal brain damage in gestational iodine deficiency and discuss the many unanswered questions, from which we propose that further clinical studies need to be designed to address the pathogenesis of neurodevelopmental impairments in the foetus and infant. Agreement on the testing instruments and standardization of processes and procedures for Intelligence Quotient (IQ) and psychomotor tests needs to be reached by investigators, so that valid comparisons can be made among studies of gestational iodine deficiency and neurocognitive outcomes. Finally, the timing, safety and the efficacy of prophylactic iodine supplementation for pregnant and lactating women needs to be established and confirmation that excess intake of iodine during pregnancy is to be avoided.

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Neonatal TSH levels in Northern Ireland from 2003 to 2014 as a measure of population iodine status

Cited by 5 publications

References 31 publications

Neonatal heel prick screening TSH concentration in the Netherlands as indicator of iodine status

Neonatal heel prick screening TSH concentration in the Netherlands as indicator of iodine status

The Role of Iodine for Thyroid Function in Lactating Women and Infants

Optimal Assessment and Quantification of Iodine Nutrition in Pregnancy and Lactation: Laboratory and Clinical Methods, Controversies and Future Directions

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