Thyroglobulin Is a Sensitive Measure of Both Deficient and Excess Iodine Intakes in Children and Indicates No Adverse Effects on Thyroid Function in the UIC Range of 100–299 μg/L: A UNICEF/ICCIDD Study Group Report

Zimmermann, Michael; Aeberli, Isabelle; Andersson, Maria; Assey, Vincent; Yorg, Jorge Antonio Jara; Jooste, P. L.; Jukić, Tomislav; Kartono, Djoko; Kusić, Zvonko; Pretell, Eduardo; Luis, Teofilo O.L. San; Untoro, Juliawati; Timmer, Arnold

doi:10.1210/jc.2012-3952

Cited by 194 publications

(186 citation statements)

References 29 publications

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“…However, when prolonged excess iodine intake occurs, Tg could increase because the thyroid gland fails to escape from the Wolff-Chaikoff effect (88). Nonetheless, close examination of data reported by Zimmermann et al (41) suggests that the relationship between UIC and Tg is highly variable. It is not known, however, how much of this variability is associated with UIC and/or Tg because a single UIC can be confounded by the hydration status, dietary intake, and diurnal variation (4).…”

Section: Childrenmentioning

confidence: 91%

“…It is suggested that this is because current Tg assays are unable to identify the heterogeneity of Tg epitopes (52,62). Of 34 articles measuring Tg (Table 1), only four (40,41,63,64) used Tg CRM-457 as an external quality control.…”

Section: Methods To Measure Tg Concentrationmentioning

confidence: 99%

“…However, in 2007, the WHO/ICCIDD/UNICEF, although acknowledging that Tg could be used an indicator of iodine status, did not provide a cutoff for Tg. More recently, Zimmermann et al (41) conducted a large multicenter study of children (n = 2512) from 12 countries with varying iodine status, and suggest that a median Tg concentration <13 lg/L and/or <3% of Tg values >40 lg/L be used as a biomarker of adequate iodine status in children and, with caution, in adults. To date, the cutoff of 13 lg/L and/or <3% of Tg values >40 lg/L has not been examined in younger children or pregnant women.…”

Section: Methods To Measure Tg Concentrationmentioning

confidence: 99%

“…Of these, nine were randomized controlled trials, two were nonrandomized controlled trials, three were cohort observational studies, 23 were cross-sectional studies (10 multicenter), and one was a monitoring report of iodization programs that included a measurement before the introduction of iodized salt to a measurement after the introduction of iodized salt. In order to investigate the consistency of the relationship between iodine status as determined by UIC and Tg more clearly, for those studies that reported this information for more than one group, we considered each of these groups separately (i.e., one study of pregnant women and their newborns (37); one study of pregnant women and adults (38); one study of children and adults (30); three studies of children living in different regions (39) or countries (40,41); and seven studies of adults living in different regions (21,25,(42)(43)(44) or countries (45,46)). …”

Section: Search Strategymentioning

confidence: 99%

“…Four studies (30,39,41,73) found that iodine-deficient children had a median Tg ‡ 13 lg/L (range 13-59 lg/L), while two studies (40,41) reported that iodine-sufficient children also had a median Tg ‡13 lg/L (range 13-19 lg/L). Four of six studies (39)(40)(41)55) reported that children with adequate iodine status had a median Tg <13 lg/L. However, one study (39) reported that iodine-deficient children had a median Tg <13 lg/L.…”

Section: Childrenmentioning

confidence: 99%

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Thyroglobulin as a Biomarker of Iodine Deficiency: A Review

Feei

Skeaff²

2014

Thyroid

137

113

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Background: Thyroglobulin, produced exclusively by the thyroid gland, has been proposed to be a more sensitive biomarker of iodine status than thyrotropin or the thyroid hormones triiodothyronine and thyroxine. However, evidence on the usefulness of thyroglobulin (Tg) to assess iodine status has not been extensively reviewed, particularly in pregnant women and adults. Summary: An electronic literature search was conducted using the Cochrane CENTRAL, Web of Science, PubMed, and Medline to locate relevant studies on Tg as a biomarker of iodine status. Since urinary iodine concentration (UIC) is the recommended method to assess iodine status in populations, only studies that clearly reported both Tg and UIC were included. For the purpose of this review, a median Tg <13 lg/L and a median UIC ‡100 lg/L (UIC ‡150 lg/L for pregnant women) were used to indicate adequate iodine status. We excluded studies conducted in subjects with either known thyroid disease or those with thyroglobulin antibodies. The search strategy and selection criteria yielded 34 articles of which nine were intervention studies. The majority of studies (six of eight) reported that iodine-deficient pregnant women had a median Tg ‡13 lg/L. However, large observational studies of pregnant women, including women with adequate and inadequate iodine status, as well as well-designed intervention trials that include both Tg and UIC, are needed. In adults, the results were equivocal because iodine-deficient adults were reported to have median Tg values of either <13 or ‡13 lg/L. Only studies in school-aged children showed that iodine-sufficient children typically had a median Tg <13 lg/L. Some of the inconsistent results may be partially explained by the use of different methodological assays and failure to assess assay accuracy using a certified reference material. Conclusions: These data suggest that Tg does hold promise as a biomarker of iodine deficiency. However, it is associated with limitations. A median Tg cutoff of 13 lg/L warrants further investigation, particularly in adults or pregnant women, as there is a lack of both observational and intervention studies in these groups.

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Section: Childrenmentioning

confidence: 91%