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REVIEW  RELEVANCE OF IODINE NUTRITION TO HEALTH IN THE 21ST CENTURY


Minerva Medica 2017 April;108(2):136-46

DOI: 10.23736/S0026-4806.17.04923-0

Copyright © 2017 EDIZIONI MINERVA MEDICA

language: English

Effect of excess iodine intake on thyroid on human health

Eftychia G. KOUKKOU 1, Nikolaos D. ROUPAS 2, Kostas B. MARKOU 2

1 “Elena Venizelou” Maternity Hospital, Athens, Greece; 2 University of Patras Medical School, University Hospital, Division of Endocrinology, Patras, Greece


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The recommended daily intake of iodide, is 150 μg for adolescents and adults, 250 μg for pregnancy and lactation. Thyroid gland is an effective collector of iodine. The active iodine uptake along the basolateral membrane of thyroid cell is followed by its transport to the apical edge of the cell and then to the follicle lumen. TSH acts through cAMP and stimulates NIS gene expression and protein synthesis. The major proportion of iodine in the thyroid gland is bound to Thyroglobulin. The non-organic intrathyroidal iodine is usually low, but significantly greater compared to plasma. Large doses of iodine reduce both the uptake and the organification (Wolff-Chaikoff effect) and cause partial inhibition of Tg proteolysis. The thyroid gland has several protective mechanisms resulting on the maintenance of normal thyroid function despite wide fluctuations of the daily iodine intake. Ingestion of several commonly used drugs and food conservatives results in acute or chronic excessive iodine intake. Failure to escape from the iodine induced organification inhibition can cause hypothyroidism, which is temporary and subsides after iodine exposure ceases. Iodine excess may also establish a status of excessive thyroid hormone synthesis and release, thus inducing autonomic thyroid function in iodopenic areas or can contribute to the development of iodine-induced hyperthyroidism in iodine abundant areas. The anti-arrhythmic Amiodarone, is a benzofuranic product with a very high iodine content, is associated with either hypo- or hyperthyroidism development. In the presence of defective auto-protective mechanisms, excessive iodine ingestion can divert the normal thyroid function.


KEY WORDS: Iodine - Thyroid gland - Hypothyroidism - Hyperthyroidism

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Publication History

Issue published online: February 20, 2017
Article first published online: January 12, 2017
Manuscript accepted: January 5, 2017
Manuscript revised: January 2, 2017
Manuscript received: November 9, 2016

Cite this article as

Koukkou EG, Roupas ND, Markou KB. Effect of excess iodine intake on thyroid on human health. Minerva Med 2017;108:136-46. DOI: 10.23736/S0026-4806.17.04923-0

Corresponding author e-mail

markoukonst@upatras.gr