Consequences of excess iodine

Leung, Angela M.; Braverman, Lewis E.

doi:10.1038/nrendo.2013.251

Cited by 470 publications

(404 citation statements)

References 75 publications

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“…It showed that median Tg appeared to follow a U-shaped curve with the nadir at an UIC of 100-300 lg/L. When iodine intake is very high, excess iodide transiently inhibits the activity of thyroid peroxidase and proteolysis of Tg, which subsequently reduces the synthesis and secretion of thyroid hormones (i.e., the Wolff-Chaikoff effect) (87). However, when prolonged excess iodine intake occurs, Tg could increase because the thyroid gland fails to escape from the Wolff-Chaikoff effect (88).…”

Section: Childrenmentioning

confidence: 99%

Thyroglobulin as a Biomarker of Iodine Deficiency: A Review

Feei

Skeaff²

2014

Thyroid

135

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: 99%

Thyroglobulin as a Biomarker of Iodine Deficiency: A Review

Feei

Skeaff²

2014

Thyroid

135

113

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“…6 Iodine toxicity can develop when consuming >1.1 mg daily. 7 In healthy subjects, excessive intake of iodine acutely inhibits thyroid hormone secretion and temporarily inhibits thyroid biosynthesis. After prolonged exposure to excessive iodine, organification and thyroid hormone biosynthesis resume in a normal fashion.…”

Section: Figurementioning

confidence: 99%

Maternal Iodine Exposure: A Case of Fetal Goiter and Neonatal Hearing Loss

et al. 2016

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A 27-year-old gravid 1 at 27 weeks 6 days with a history of hypothyroidism had an ultrasound that demonstrated a 3.9 × 3.2 × 3.3-cm well-circumscribed anterior neck mass, an extended fetal head, and polyhydramnios. Further characterization by magnetic resonance imaging (MRI) showed a fetal goiter. During her evaluation for the underlying cause of the fetal goiter, the patient revealed she was taking nutritional iodine supplements for treatment of her hypothyroidism. She was ingesting 62.5 times the recommended amount of daily iodine in pregnancy. The excessive iodine consumption caused suppression of the fetal thyroid hormone production, resulting in hypothyroidism and goiter formation. After the iodine supplement was discontinued, the fetal goiter decreased in size. At delivery, the airway was not compromised. The infant was found to have reversible hypothyroidism and bilateral hearing loss postnatally. This case illustrates the importance of examining for iatrogenic causes for fetal anomalies, especially in unregulated nutritional supplements.

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“…The washing operation has been repeated twice. At selected intervals (1,2,4,6,8,12,20 and 24 h) 1.5 ml of the dermal bathing solution was removed and collected for the analyses. Each receptor sample was immediately replaced with an equal volume of fresh made physiological solution.…”

Section: The Experimentsmentioning

confidence: 99%

“…In animal experiments, transcutaneous absorption of PI through healthy skin has also been examined using radioisotope I125 (Furudate et al, 1997). In individuals with dysregulation of the thyroid follicular cell, excess iodine exposure can induce thyroid dysfunction, which might be transient or permanent (Leung and Braverman, 2014). The aim of our study was to calculate the skin absorption of iodine after the application on the skin of povidone-iodine solution used by health care workers during surgical procedures.…”

Section: Introductionmentioning

confidence: 99%

Povidone iodine skin absorption: An ex-vivo study

et al. 2015

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Povidone iodine is a water-soluble complex used to disinfect the skin surface and it exerts prolonged germicidal action against a broad spectrum of germs. Indeed, it is often applied on burned skin, large wounds, deep tissues or mucosa. Notably some surgical hand-scrub solutions, which are considered safe antiseptics, contain large amounts of iodine that can be absorbed by skin. The aim of present study was to study the skin absorption of iodine after the application on the skin of povidone-iodine solution, used by health care workers during surgical procedure. We use Franz diffusion static cells with human skin. After 24h from the beginning of our measurement the iodine concentration in the receiving compartment was 11.59±6.3μg/cm(2). The medium flux calculated was 0.73±0.33μg/cm(2)/h with a lag time of 8.9±1.5h. These in vitro results confirmed that povidone iodine could pass through the skin in a relevant amount that can explain the clinical findings in burned or surgically treated patients. In professional use the repetitive contact with povidone iodine, also as soap, can cause iodine skin permeation that must be considered when the washing procedures are repeated more than 20 times a day

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Consequences of excess iodine

Cited by 470 publications

References 75 publications

Thyroglobulin as a Biomarker of Iodine Deficiency: A Review

Thyroglobulin as a Biomarker of Iodine Deficiency: A Review

Maternal Iodine Exposure: A Case of Fetal Goiter and Neonatal Hearing Loss

Povidone iodine skin absorption: An ex-vivo study

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