Iodide transport: implications for health and disease

Abstract

Disorders of the thyroid gland are among the most common conditions diagnosed and managed by pediatric endocrinologists. Thyroid hormone synthesis depends on normal iodide transport and knowledge of its regulation is fundamental to understand the etiology and management of congenital and acquired thyroid conditions such as hypothyroidism and hyperthyroidism. The ability of the thyroid to concentrate iodine is also widely used as a tool for the diagnosis of thyroid diseases and in the management and follow up of the most common type of endocrine cancers: papillary and follicular thyroid cancer. More recently, the regulation of iodide transport has also been the center of attention to improve the management of poorly differentiated thyroid cancer. Iodine deficiency disorders (goiter, impaired mental development) due to insufficient nutritional intake remain a universal public health problem. Thyroid function can also be influenced by medications that contain iodide or interfere with iodide metabolism such as iodinated contrast agents, povidone, lithium and amiodarone. In addition, some environmental pollutants such as perchlorate, thiocyanate and nitrates may affect iodide transport. Furthermore, nuclear accidents increase the risk of developing thyroid cancer and the therapy used to prevent exposure to these isotopes relies on the ability of the thyroid to concentrate iodine. The array of disorders involving iodide transport affect individuals during the whole life span and, if undiagnosed or improperly managed, they can have a profound impact on growth, metabolism, cognitive development and quality of life.

Hyperthyroidism secondary to hysterosalpingography

“…Seventy to 80% of the iodine content is located in the thyroid gland. [6] Organic binding of iodine in the thyroid is decreased when plasma iodide levels are elevated (acute Wolff–Chaikoff effect). Adaptation to this acute effect occurred in approximately 2 days, in the presence of constant high levels of iodide concentrations in plasma.…”

“…[7] Thyroid clearance varies depending on iodine intake, ranging from 10% of absorbed iodide in healthy individuals to more than 80% in patients with chronic iodine deficiency. [6] Guitierrez-Repiso et al [8] observed that in an adult population with adequate and stable nutrition, iodine excretion in a random urine sample represented 70% to 80% of daily iodine intake. Therefore, median urinary iodine concentrations (UIC) are widely used as a biomarker of population iodine intake, with levels >300 μg/L considered excessive in children and adults, and levels >500 μg/L considered excessive in pregnant women.…”

“…Patients with type II thyrotoxicosis may develop permanent hypothyroidism due to fibrosis of the thyroid gland. [3,6,9] In severely ill patients, treating both AIT1 and AIT2 with anti-thyroid drugs and glucocorticoids with or without perchlorate reduces thyroid inflammation and also reduces the peripheral conversion of T4 to T3. [5,9,10] …”

Impact of Na+/I– symporter to non-oncologic pathology of the thyroid

“…Регуляторное влияние половых гормонов на синтез НйС менее изучено. Имеются данные о способности эстрадиола подавлять экспрессию НйС [17]. В то же время в других исследованиях показано, что с наступлением половой зрелости в щитовидной железе самок происходит активация синтеза НйС [18].…”

Primary Thyroid Stimulating Hormone Screening for Congenital Hypothyroidism in King Abdullah Hospital, Bisha, Saudi Arabia

“…Congenital hypothyroidism (CH) is the most common pediatric endocrine disorder [1,2]. CH is sporadic and occurs in 1:1500 to 1:4000 newborns, making it one of the most common causes of preventable mental retardation [3][4][5].…”