Selenium (Se) in urine (chromatography)
Selenium is an essential trace element that is a key component of some vital selenoproteins and enzymes. Such Se-dependent enzymes include the antioxidant glutathione peroxidase, which neutralizes free radicals and peroxidation of lipids, protects the cell from their damaging effects on the structure and functions of membranes. Antioxidant enzymes of the cell prevent oxidative stress, which contributes to the development of many diseases. Selenoproteins are part of the enzymes iodothyronine deiodinase I, thyredoxin reductase and are involved in the regulation of thyroid function.
In large doses, selenium causes poisoning - selenism. For humans, the toxic dose of selenium is 5 mg. Selenotoxicosis can occur with excessive use of food additives containing selenium, or when working in foundries, electronic, copper smelters, oil refineries, chemical industries. In industry, selenium is obtained as a byproduct of copper processing. It is used in electronic semiconductors, as a discoloring agent for ceramics and glass, and as a vulcanizing agent in tire manufacturing. Intoxication is manifested by garlic taste in the mouth (associated with the formation of dimethyl selenide), nausea, hair loss, brittle nails, dermatitis, damage to the nervous system in the form of numbness, convulsions or paralysis of the extremities, possible disorders of the psycho-emotional state.