Standardized Map of Iodine Status in Europe
Journal
Thyroid : official journal of the American Thyroid Association
Date Issued
2020-05-28
Author(s)
Ittermann, Till
Albrecht, Diana
Arohonka, Petra
Bílek, Radovan
Dahl, Lisbeth
Castro, João Jácome
Filipsson Nyström, Helena
Gaberšček, Simona
Garcia-Fuentes, Eduardo
Gheorghiu, Monica
Hubalewska-Dydejczyk, Alicija
Hunziker, Sandra
Jukic, Tomislav
Karanfilski, Borislav
Koskinen, Seppo
Kusic, Zvonko
Makris, Konstantinos
Markou, Kostas
Meisinger, Christa
Milevska Kostova, Neda
Mullan, Karen R
Nagy, Endre V
Pīrāgs, Valdis
Rojo-Martinez, Gemma
Samardzic, Mira
Saranac, Ljiljana
Strele, Ieva
Top, Işık
Thamm, Michael
Trofimiuk-Müldner, Malgorzata
Unal, Belgin
Valsta, Liisa
Vila, Lluis
Vitti, Paolo
Winter, Benjamin
Woodside, Jayne
Zaletel, Katja
Zamrazil, Vaclav
Zimmermann, Michael
Erlund, Iris
Völzke, Henry
DOI
10.1089/thy.2019.0353
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 UIC data. 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 post-harmonize the studies by standardizing the UIC data of the individual studies. Results In comparison to 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 post-harmonized 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 demonstrated 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 non-iodized 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.