Iodine, I

Abstract

Iodine is not a common element in nature, so many regions of the world suffer rather from a deficiency than an overabundance. The northern part of North America, most of South America, Africa, Asia (Himalaya), and Europe are classified as endemic regions with low iodine content. Iodine plays a crucial role in the thyroid for hormone synthesis, which in turn regulates the regularity of most of metabolic pathways in mammalian cells. An iodine deficiency in animals causes malformation, growth retardation, decreased fertility, increased perinatal mortality, and lowered animal performance and productivity, e.g., reduced growth of wool, egg, and milk production. Moreover it has been shown that in roe deer, iodine-containing hormones play a role in the complex neurohormonal regulation of antler development. Antler weight increases with increasing iodine concentration. The content of iodine in wild range animals is subject to evaluation only occasionally. For most wild-ranging species of mammals and birds, there is no information about iodine requirements. As more than 90% of dietary iodine is expelled by the kidneys, urine is found to be a good study material to assess recent iodine intake.