The Disorders Induced by Iodine Deficiency

Abstract

This paper reviews present knowledge on the etiology, pathophysiology, complications, prevention, and therapy of the disorders induced by iodine deficiency. The recommended dietary allowances of iodine are 100 micrograms/day for adults and adolescents, 60-100 micrograms/day for children aged 1 to 10 years, and 35-40 micrograms/day in infants aged less than 1 year. When the physiological requirements of iodine are not met in a given population, a series of functional and developmental abnormalities occur including thyroid function abnormalities and, when iodine deficiency is severe, endemic goiter and cretinism, endemic mental retardation, decreased fertility rate, increased perinatal death, and infant mortality. These complications, which constitute a hindrance to the development of the affected populations, are grouped under the general heading of iodine deficiency disorders (IDD). At least one billion people are at risk of IDD. Iodine deficiency, therefore, constitutes one of the most common preventable causes of mental deficiency in the world today. Most of the affected populations live in mountainous areas in preindustrialized countries, but 50 to 100 million people are still at risk in Europe. The most important target groups to the effects of iodine deficiency from a public health point of view are pregnant mothers, fetuses, neonates, and young infants because the main complication of IDD, i.e., brain damage resulting in irreversible mental retardation, is the consequence of thyroid failure occurring during pregnancy, fetal, and early postnatal life. The main cause of endemic goiter and cretinism is an insufficient dietary supply of iodine. The additional role of naturally occurring goitrogens has been documented in the case of certain foods (milk, cassava, millet, nuts) and bacterial and chemical water pollutants. The mechanism by which the thyroid gland adapts to an insufficient iodine supply is to increase the trapping of iodide as well as the subsequent steps of the intrathyroidal metabolism of iodine leading to preferential synthesis and secretion of triiodotyronine (T3). They are triggered and maintained by increased secretion of TSH, which is ultimately responsible for the development of goiter. The acceleration of the main steps of iodine kinetics and the degree of hyperstimulation by TSH are much more marked in the pediatric age groups, including neonates, than in adults, and the development of goiter appears as an unfavorable side effect in the process of adaptation to iodine deficiency during growth. The most serious complication of iodine deficiency is endemic cretinism, a syndrome characterized by irreversible mental retardation together with either a predominant neurological syndrome or predominant hypothyroidism, or a combination of both syndromes.(ABSTRACT TRUNCATED AT 400 WORDS)

Iodide Recognition and Sensing in Water by a Halogen‐Bonding Ruthenium(II)‐Based Rotaxane

“…Recognition in this highly competitive protic media has predominantly been the domain of highly charged hydrogen‐bonding receptors, which are frequently pH‐dependent3 or metal‐cation‐based systems;4–6 although some recent progress has been made in exploiting the hydrophobic effect for anion recognition by neutral host species 7–10. Amongst the plethora of biologically and medically relevant anions, the recognition and sensing of iodide in water is of interest both due to its crucial role in hormone biosynthesis by the thyroid gland11, 12 and its use in contrast media for radiographic imaging applications 13. Examples of anion hosts capable of sensing iodide by optical methods are scarce,14–17 and to the best of our knowledge, the use of molecular‐anion receptors for the host–guest recognition and sensing of iodide in water is unprecedented.…”

Endemic goitre in the absence of iodine deficiency in schoolchildren of the Northern Cape Province of South Africa

“…The most likely source of the high iodine intake in these children is the drinking water with high iodine concentrations, particularly in Victoria West, Kenhardt and Brandvlei (Table 1). A litre of water in these towns contains an adequate amount of iodine to provide the daily requirement for this micronutrient (150 ± 200 mg per day for adults, less in children (Delange, 1994)) and it is likely that the inhabitants' water intake in this hot and dry climate may be in excess of one litre per day.…”

“…Endemic goitre, prevailing in many countries of the globe, is usually caused by iodine de®ciency (Delange, 1994;Hetzel, 1996). However, in some areas endemic goitre could also be caused or aggravated by substances found in certain foods or water that are collectively termed goitrogens.…”

Novel two-dimensional morphometric maps and quantitative analysis reveal marked growth and structural recovery of the rat hippocampal regions from early hypothyroid retardation

“…This is curious in light of the prominent role the HC plays in normal cognitive functions (Cohen & Eichenbaum, 1993;Olton et al 1979;Zola-Morgan, et al, 1986) and the profound mental retardation and cognitive impairments associated with severe cases of neurological cretinism (Delange, 1994;Smith et al, 2002). In addition to its unique functions in congition, the HC has been shown to display marked neural plasticity, as well as pronounced vulnerability to ischemia and other hormonal and metabolic effects (Bothe et al, 1986;Gould et al 1991;Masliah et al, 1992;Nawashiro et al, 1995;Sapolsky et al, 1985;Sloviter et al1989;Smith et al, 1994;Zola-Morgan et al, 1986).…”