par Panneels, Valérie ;Juvenal, Guillermo ;Boeynaems, Jean-Marie ;Dumont, Jacques Emile ;Van Sande, Jacqueline
Référence Comprehensive Handbook of Iodine, Elsevier Inc., page (303-314)
Publication Publié, 2009
Partie d'ouvrage collectif
Résumé : This chapter presents the direct physiological and pharmacological controls of the thyroid by iodide. In vivo studies in humans and animals have demonstrated that at low or physiological levels, iodide uptake limits the synthesis of thyroid hormones and therefore their secretion. These serum thyroid hormones depress the secretion of the main physiological activator of the gland, pituitary thyroid stimulating hormone (TSH). Thus, iodine deficiency leads to decreased thyroid hormone levels and compensatory TSH secretion. At these levels, there is an inverse relationship between iodide supply and TSH secretion. Iodide also directly inhibits the activity and growth of the thyroid due to the generation of an organified inhibitor XI in the thyroid. The direct effects of iodide and XI account for an inhibition of iodide oxidation itself, of iodide uptake, and of thyroid hormone secretion and thyroid growth. Besides the XI effects, iodide at very high pharmacological or toxicological concentrations appears to directly inhibit thyroid blood flow and secretion. The latter effects are used in the preoperative treatment of patients suffering from Graves' disease with Lugol. The indirect effects of iodide through thyroid hormones are observed at low or physiological levels of iodide intake and serum concentrations. The direct effects are mostly observed at supraphysiological, therapeutic, or toxic levels. The chapter also describes the clinical consequences of the diverse iodide actions the various experimental models used to elucidate the direct effects of iodide on the thyroid are discussed and analyzed. © 2009 Elsevier Inc. All rights reserved..

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