Globally, about 2 thousand million people are affected by iodine deficiency. Although endemic goitre is the most visible sign of iodine deficiency, its most devastating consequence is brain damage causing mental retardation in children. The relationship between iodine deficiency and brain damage was not clearly established until the 1980s when the term iodine deficiency disorders (IDDs), which encompass a spectrum of conditions caused by iodine deficiency, was introduced. This paradigm shift in the understanding of the clinical consequences of iodine deficiency led to a change in iodine deficiency assessment. The median urinary iodine excretion level has been recommended as the preferred indicator for monitoring population iodine deficiency status since 2001. The 2007 WHO urinary iodine data in schoolchildren from 130 countries revealed that iodine intake is still insufficient in 47 countries. Furthermore, about one-third of countries lack national estimates of the prevalence of iodine deficiency. The picture that has emerged from available data worldwide over the past two decades is that IDDs are not confined to remote, mountainous areas in developing countries, but are a global public health problem that affects most countries, including developed countries and island nations. The recognition of the universality of iodine deficiency highlights the need to develop and apply new strategies to establish and maintain sustainable IDD elimination and strengthen regular monitoring programmes.
Despite efforts to monitor changes in the magnitude of iodine deficiency worldwide, prevalence data are crude and are still not available for many countries
Iodine deficiency is re-emerging in some developed countries; therefore, public awareness and government policies on iodine fortification, supplementation and surveillance of iodine deficiency are warranted
Currently, the WHO, UNICEF and ICCIDD recommend using median urinary iodine concentration in school-age children as a proxy for the iodine nutrition status of the general population
The applicability of this recommendation for the most vulnerable population groups, such as pregnant women and young children, needs to be reviewed
At the population level, close monitoring and surveillance of iodine intake is an important public health measure to ensure optimal iodine nutrition
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The authors declare no competing financial interests.
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Li, M., Eastman, C. The changing epidemiology of iodine deficiency. Nat Rev Endocrinol 8, 434–440 (2012). https://doi.org/10.1038/nrendo.2012.43
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