Obesity and Monitoring Iodine Nutritional Status in Schoolchildren: is Body Mass Index a Factor to Consider?

Angelis, Simona De; Bagnasco, Marcello; Moleti, Mariacarla; Regalbuto, Concetto; Tonacchera, Massimo; Vermiglio, Francesco; Medda, Emanuela; Rotondi, Daniela; Cosmo, Caterina Di; Dimida, Antonio; Rago, Teresa; Schiavo, Mara; Nazzari, Elena; Bossert, Irene; Sturniolo, Giacomo Carlo; Cesaretti, G; Olivieri, Antonella

doi:10.1089/thy.2020.0189

Cited by 22 publications

(19 citation statements)

References 44 publications

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“…Only few data, to our knowledge, have been published concerning the prevalence of hypoechoic pattern, typical of autoimmune thyroiditis following implementation of iodoprophylaxis with iodized salt: Miranda et al, in Brazil, reported an increase of hypoechoic pattern in children following attainment of high (300 µg/L or more) UIC concentration, and a trend to decrease when the target was adjusted at 165 µg/L [73]. In addition, in a recent study reporting data after a decade of iodine prophylaxis on voluntary basis in Italy [82], the frequency of moderately or markedly hypoechoic patterns in schoolchildren residing in iodine-sufficient areas (median UIC value 129 μg/L) was 6.6%, whereas it was significantly higher (10.9%) in an area of Sicily region where UIC value was still under the desired target value (median UIC value 89 μg/L). Even more importantly, in Liguria, one of the studied Italian regions where comparative dataset collected 8 years before (i.e., 2 years following iodized salt consumption implementation) were available, no increase in the frequency of hypoechoic pattern was observed (3.3% at 2, 2.7% at 10 years) despite a significant reduction in goiter prevalence.…”

Section: Discussionmentioning

confidence: 99%

Iodoprophylaxis and thyroid autoimmunity: an update

Teti¹,

Panciroli

Nazzari

et al. 2021

Immunol Res

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Adequate iodine intake is necessary for normal thyroid function. Iodine deficiency is associated with serious complications, but also iodine excess can lead to thyroid dysfunction, and iodine supplementation aimed to prevent iodine deficiency disorders has been associated with development of thyroid autoimmunity. The epidemiology of thyroid diseases has undergone profound changes since the implementation of iodoprophylaxis, notably by means of iodine-enriched salt, specifically resulting in decreased prevalence of goiter and neonatal hypothyroidism, improved cognitive function development in infancy, and reduced incidence of more aggressive forms of thyroid cancer. The main question we address with this review is the clinical relevance of the possible effect on autoimmunity exerted by the use of iodine-enriched salt to correct iodine deficiency. In animal models, exogenous iodine is able to trigger or exacerbate thyroid autoimmunity, but it is still not clear whether the observed immunological changes are due to a direct effect of iodine on immune response, or whether they represent a secondary response to a toxic effect of iodine on thyroid tissue. Previous iodine status of a population seems to influence the functional thyroid response to increased iodine intake and possibly the development of thyroid autoimmunity. Moreover, the prevalence of thyroid antibodies, regarded as hallmark of autoimmune thyroid disease, varies between populations under the influence of genetic and environmental factors, and the presence of thyroid antibodies does not always coincide with the presence of thyroid disease or its future development. In addition, the incidence of autoimmune diseases shows a general increasing trend in the last decades. For all these reasons, available data are quite heterogeneous and difficult to analyze and compare. In conclusion, available data from long-term population surveys show that a higher than adequate population iodine intake due to a poorly controlled program of iodine prophylaxis could induce thyroid dysfunction, including thyroid autoimmunity mostly represented by euthyroid or subclinical hypothyroid autoimmune thyroiditis. Close monitoring iodine prophylaxis is therefore advised to ensure that effects of both iodine deficiency and iodine excess are avoided.

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Section: Discussionmentioning

confidence: 99%

Iodoprophylaxis and thyroid autoimmunity: an update

Teti¹,

Panciroli

Nazzari

et al. 2021

Immunol Res

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“…Interactions of vitamin A/D and iodine deficiencies on thyroid function were also reported [ 13 , 14 ], and evidence suggests that thyroid dysfunction can easily lead to obesity, and vice versa [ 15 ]. Moreover, a recent study for the first time demonstrates that BMI may be a confounding factor in monitoring iodine nutritional status in schoolchildren [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

Iodine Nutritional Status and Related Factors among Chinese School-Age Children in Three Different Areas: A Cross-Sectional Study

Liu

Luo

et al. 2021

Nutrients

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We evaluated the iodine nutritional status and related factors among school-age children based on the 2016 National Nutrition and Health Surveillance of Children and Lactating Women; 3808 children from Hebei, Guangxi, and Zhejiang province were included in the study. Urinary iodine concentration (UIC), thyroid-stimulating hormone (TSH), body mass index (BMI), vitamin A (VA), and vitamin D (VD) were measured. The abnormal rate of UIC and TSH were assessed. Relationships between UIC/TSH and the possible factors were analyzed. The overall median UIC was 185.14 µg/L, and the median UIC of children aged 8–10 was 164.60 µg/L. Prevalence of iodine deficiency and excess was 13.84% and 14.36%, respectively, and 12.87% of children showed TSH excess. UIC, as well as the abnormal rates of iodine deficiency (ID) and TSH, were significantly different among the three provinces. The median UICs and excess rates increased with age, reaching 211.45 µg/L and 21.35% at age of 14~, while TSH showed the opposite trend. Overweight children tended to have lower UIC and higher TSH. Higher UIC and TSH were found in VA sufficient group (p < 0.01). Further, the VD deficient group had a higher TSH compared to the sufficient group (p < 0.01). Moreover, UI and TSH distribution was obviously different among different vitamin A/D status (p < 0.05). Although the median UIC of school-age children was optimal, there were pockets of inadequate and excessive UI in the three provinces. Compared to the national IDD monitoring results in 2014, the iodine nutritional status of children was greatly improved. Considerations of region, age, BMI, VA, or VD are needed in the future iodine evaluation and surveillance.

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“…In particular, in iodine sufficient children median UIC was significantly lower in obese than in normal-weight children (102 μg/L vs 135 μg/L), whereas no significant difference was observed between the latter and overweight children (135 μg/L vs 118 μg/L). By contrast, in mildly iodine deficient children UIC was similar in all the above BMI categories, although obese boys had a median UIC value indicative of iodine sufficiency (113 μg/L) and obese girls of iodine deficiency (84 μg/L) [ 13 ]. Whether these findings were due to a true effect of BMI or to confounding factors, such as severity of obesity or social and economic factors, could not be ascertained in this study, since no information was collected on education and economic status of children’s parents.…”

Section: Introductionmentioning

confidence: 99%

“…A positive correlation between thyroid gland size and body weight was first reported almost 40 years ago by Hegedüs and colleagues, who also found no significant differences in the thyroid volume/body weight ratio between males and females in an unselected population of 271 healthy normal-weight subjects (age 13–91 years) from a moderate iodine deficient area [ 19 ]. Similarly, thyroid volume has been shown to increase with the increasing of anthropometric parameters, either in adults [ 20 – 25 ] or in children [ 13 , 26 – 29 ], irrespective of the nutritional iodine status.…”

Section: Introductionmentioning

confidence: 99%

“…Very recently, data on the effects of overweight and obesity on thyroid volume in schoolchildren were provided [ 13 ]. The study population was part of a nationwide survey carried out by the Italian National Observatory for Iodine Prophylaxis and included 1281 children aged 11–13 years residing in iodine-sufficient regions (IS-group, median UIC 129 μg/L) and 314 age-matched children from a mildly iodine deficient area (ID-group, median UIC 89 μg/L) within the same country (Italy) [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

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Nutritional iodine status and obesity

et al. 2021

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Iodine is an essential component of the thyroid hormones, thyroxine and triiodothyronine. Its availability strictly depends on iodine content of foods, which may vary from very low to very high. Inadequate iodine intake (deficiency or excess) may affect thyroid function resulting in hypothyroidism or hyperthyroidism. Based on median urinary iodine concentrations, epidemiological criteria have been established for the categorization and monitoring of nutritional iodine status of a population (or subgroups of populations). Additional methods for iodine intake assessment include measurement of thyroid size (by thyroid palpation or ultrasonography) and of biochemical parameters, such as neonatal thyroid stimulating hormone, thyroglobulin and thyroid hormones.Recent studies carried out in overweight/obese children and adults provide evidence that body mass index (BMI) may significantly influence the above indicators, thus theoretically affecting the epidemiological evaluation of nutritional iodine status in populations.In this short review, we analyze current knowledge on the effects of overweight and obesity on indicators of adequacy and monitoring of iodine status, namely urinary iodine excretion and thyroid volume and echogenicity.Data on urinary iodine excretion in overweight/obese children are divergent, as both increased and reduced levels have been reported in overweight/obese children compared to normal-weight controls.Whether gastrointestinal surgery may affect iodine absorption and lead to iodine deficiency in patients undergoing bariatric surgery has been evaluated in a limited number of studies, which excluded iodine deficiency, thus suggesting that supplements usually recommended after bariatric surgery do not need to include iodine.Albeit limited, evidence on thyroid volume and obesity is consistent with a direct relationship between thyroid volume and BMI, irrespective of nutritional iodine status. Finally, a higher frequency of thyroid hypoechoic pattern has been described in overweight/obese children. This finding has been recently related to an increased adipocyte infiltration and thyroid parenchyma imbibition mediated by inflammatory cytokines and should be considered when the frequency of thyroid hypoechoic pattern is used as non-invasive marker to indirectly assess thyroid autoimmunity in monitoring Universal Salt Iodization programs. Further studies, specifically addressing the role of schoolchildren body mass index as a factor potentially influencing iodine intake indicators are needed.

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Obesity and Monitoring Iodine Nutritional Status in Schoolchildren: is Body Mass Index a Factor to Consider?

Cited by 22 publications

References 44 publications

Iodoprophylaxis and thyroid autoimmunity: an update

Iodoprophylaxis and thyroid autoimmunity: an update

Iodine Nutritional Status and Related Factors among Chinese School-Age Children in Three Different Areas: A Cross-Sectional Study

Nutritional iodine status and obesity

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