Leung Angela, Pearce Elizabeth N, Braverman Lewis E
a Boston University Medical Center, Section of Endocrinology, Diabetes, and Nutrition, 88 East Newton Street, Evans 201, Boston, MA 02118, USA.
b
Expert Rev Endocrinol Metab. 2010 Jul;5(4):593-602. doi: 10.1586/eem.10.40.
Adequate levels of iodine, a trace element variably distributed on the earth, are required for the synthesis of the thyroid hormones thyroxine (T) and triiodothyronine (T). The iodide cycle consists of a series of transport, oxidation and coupling steps in thyroid follicular cells to produce thyroid hormone. The sodium/iodide symporter (NIS) transports iodide into the thyrocyte. Competitive inhibitors of NIS, such as perchlorate and thiocyanate, can decrease the entrance of iodide into the follicular cell. Pendrin is the primary protein that is responsible for iodide efflux out of the thyrocyte and into the follicular lumen. T is deiodinated in target tissues to produce the active form of thyroid hormone, T, and other metabolites. Exposure to excessive iodine or chronic iodine deficiency may result in various clinical disorders. The Wolff-Chaikoff effect and Jöd-Basedow phenomenon describe mechanisms of thyroid autoregulation and dysregulation, respectively, during iodine excess. Population studies have determined that iodine deficiency exists in approximately 38% of the world's population, is the leading cause of preventable mental retardation, and is of particular concern to women and their infants. Finally, the unique role of iodine utilization in thyroid physiology has applications in many important clinical areas.
碘是一种在地球上分布不均的微量元素，甲状腺激素甲状腺素（T）和三碘甲状腺原氨酸（T）的合成需要适量的碘。碘循环由甲状腺滤泡细胞中的一系列转运、氧化和偶联步骤组成，以产生甲状腺激素。钠/碘同向转运体（NIS）将碘转运进入甲状腺细胞。NIS的竞争性抑制剂，如高氯酸盐和硫氰酸盐，可减少碘进入滤泡细胞。pendrin是负责碘从甲状腺细胞流出并进入滤泡腔的主要蛋白质。T在靶组织中脱碘，产生甲状腺激素的活性形式T和其他代谢产物。接触过量碘或长期碘缺乏可能导致各种临床疾病。Wolff-Chaikoff效应和Jöd-Basedow现象分别描述了碘过量时甲状腺自动调节和调节异常的机制。人群研究已确定，全球约38%的人口存在碘缺乏，这是可预防智力迟钝的主要原因，尤其值得妇女及其婴儿关注。最后，碘在甲状腺生理学中的独特利用作用在许多重要临床领域都有应用。
