Selenium and thyroid hormone metabolism

Selenium is an essential trace element for both men and animals at lower concentrations and has toxic effects at higher concentrations. The element’s essentiality was first recognised in 1957. Low bioavailability could be contributing to cancers, cardiovascular disease, and subfertility. Selenium and its compounds are widely used in stainless steel production, as a pigment in ceramics, vulcanizing agent of rubber, lubricants, fungicides, medicines used in dermatology and in radionulide imaging of the pancreas. Selenium’s annual world production is estimated at 1,350 tonnes. In the last decade selenium was shown to be an essential component of type I oidothyronine 5’ deiodinase which converts tyroxin to the more biologically active hormone 3,5,3’‐triiodothyronine. The function of selenium in thyroid hormone metabolism has important implications for the interpretation of the effects of selenium deficiency, especially in an elderly population. The population of the elderly has grown in numbers during recent years, throughout the world. The thyroid gland function in a great measure defines the quality of life in elderly people. The purpose of this review is to show the role of selenium in thyroid hormone metabolism.