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First published online May 28, 2020

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Standardized Map of Iodine Status in Europe

Volume 30, Issue 9

https://doi.org/10.1089/thy.2019.0353

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Abstract
References

Abstract

Background:

Knowledge about the population's iodine status is important, because it allows adjustment of iodine supply and prevention of iodine deficiency. The validity and comparability of iodine-related population studies can be improved by standardization, which was one of the goals of the EUthyroid project. The aim of this study was to establish the first standardized map of iodine status in Europe by using standardized urinary iodine concentration (UIC) data.

Materials and Methods:

We established a gold-standard laboratory in Helsinki measuring UIC by inductively coupled plasma mass spectrometry. A total of 40 studies from 23 European countries provided 75 urine samples covering the whole range of concentrations. Conversion formulas for UIC derived from the gold-standard values were established by linear regression models and were used to postharmonize the studies by standardizing the UIC data of the individual studies.

Results:

In comparison with the EUthyroid gold-standard, mean UIC measurements were higher in 11 laboratories and lower in 10 laboratories. The mean differences ranged from −36.6% to 49.5%. Of the 40 postharmonized studies providing data for the standardization, 16 were conducted in schoolchildren, 13 in adults, and 11 in pregnant women. Median standardized UIC was <100 μg/L in 1 out of 16 (6.3%) studies in schoolchildren, while in adults 7 out of 13 (53.8%) studies had a median standardized UIC <100 μg/L. Seven out of 11 (63.6%) studies in pregnant women revealed a median UIC <150 μg/L.

Conclusions:

We demonstrate that iodine deficiency is still present in Europe, using standardized data from a large number of studies. Adults and pregnant women, particularly, are at risk for iodine deficiency, which calls for action. For instance, a more uniform European legislation on iodine fortification is warranted to ensure that noniodized salt is replaced by iodized salt more often. In addition, further efforts should be put on harmonizing iodine-related studies and iodine measurements to improve the validity and comparability of results.

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References

1. World Health Organization 2007 Assessment of Iodine Deficiency Disorders and Monitoring their Elimination. A Guide for Programme Managers (Third edition). Available at https://apps.who.int/iris/bitstream/handle/10665/43781/9789241595827_eng.pdf (accessed July9, 2020).

2. Iodine Global Network. Global map of iodine nutrition. Available at www.ign.org/scorecard.htm (accessed July9, 2020).

3. Zimmermann MB, Andersson M. 2012. Update on iodine status worldwide. Curr Opin Endocrinol Diabetes Obes, 19:382–387.

4. Ittermann T, Johner S, Below H, Leiterer M, Thamm M, Remer T, Volzke H. 2018. Interlaboratory variability of urinary iodine measurements. Clin Chem Lab Med, 56:441–447.

5. Nystrom HF, Brantsaeter AL, Erlund I, Gunnarsdottir I, Hulthen L, Laurberg P, Mattisson I, Rasmussen LB, Virtanen S, Meltzer HM. 2016. Iodine status in the Nordic countries—past and present. Food Nutr Res, 60:31969.

6. Volzke H, Caron P, Dahl L, de Castro JJ, Erlund I, Gaberscek S, Gunnarsdottir I, Hubalewska-Dydejczyk A, Ittermann T, Ivanova L, Karanfilski B, Khattak RM, Kusic Z, Laurberg P, Lazarus JH, Markou KB, Moreno-Reyes R, Nagy EV, Peeters RP, Pirags V, Podoba J, Rayman MP, Rochau U, Siebert U, Smyth PP, Thuesen BH, Troen A, Vila L, Vitti P, Zamrazil V, Zimmermann MB. 2016. Ensuring effective prevention of iodine deficiency disorders. Thyroid, 26:189–196.

7. Lazarus JH. 2014. Iodine status in Europe in 2014. Eur Thyroid J, 3:3–6.

8. The EUthyroid Consortium. EUthyroid Data Exchange System Available at https://dex.euthyroid.medizin.uni-greifswald.de/dex/ (accessed December9, 2018).

9. Eurostat. 2007. Regions in the European Union. Nomenclature of territorial units for statistics—NUTS 2006/EU-27. Office for Official Publications of the European Communities, Luxembourg.

10. Cashman KD, Dowling KG, Skrabakova Z, Kiely M, Lamberg-Allardt C, Durazo-Arvizu RA, Sempos CT, Koskinen S, Lundqvist A, Sundvall J, Linneberg A, Thuesen B, Husemoen LL, Meyer HE, Holvik K, Gronborg IM, Tetens I, Andersen R. 2015. Standardizing serum 25-hydroxyvitamin D data from four Nordic population samples using the Vitamin D Standardization Program protocols: shedding new light on vitamin D status in Nordic individuals. Scand J Clin Lab Invest, 75:549–561.

11. Diaz A, Lipman Diaz EG. 2014. Hypothyroidism. Pediatr Rev, 35:336–347; quiz 348–339.

12. Rasmussen LB, Ovesen L, Bulow I, Jorgensen T, Knudsen N, Laurberg P, Pertild H. 2002. Dietary iodine intake and urinary iodine excretion in a Danish population: effect of geography, supplements and food choice. Br J Nutr, 87:61–69.

13. Thamm M, Ellert U, Thierfelder W, Liesenkotter KP, Volzke H. 2007. [Iodine intake in Germany. Results of iodine monitoring in the German Health Interview and Examination Survey for Children and Adolescents (KiGGS)]. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz, 50:744–749.

14. Dahl L, Opsahl JA, Meltzer HM, Julshamn K. 2003. Iodine concentration in Norwegian milk and dairy products. Br J Nutr, 90:679–685.

15. Johner SA, Shi L, Remer T. 2010. Higher urine volume results in additional renal iodine loss. Thyroid, 20:1391–1397.

16. Ittermann T, Volzke H, Krey A, Remer T, Heckmann M, Lange A, Kramer A, Below H. 2019. Median urinary iodine concentration reflected sufficient iodine supply in neonates from Northeast Germany in 2005–2006. Eur J Nutr, 58:1815–1820.

17. Bath SC, Rayman MP. 2015. A review of the iodine status of UK pregnant women and its implications for the offspring. Environ Geochem Health, 37:619–629.

18. Zimmermann MB, Andersson M. 2012. Assessment of iodine nutrition in populations: past, present, and future. Nutr Rev, 70:553–570.

19. Andersen S, Karmisholt J, Pedersen KM, Laurberg P. 2008. Reliability of studies of iodine intake and recommendations for number of samples in groups and in individuals. Br J Nutr, 99:813–818.

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