HGH is touted by some as the elixir of youth of the 21st century. Its "legitimate" use is for pituitary-related child dwarfism, although an article in The Lancet gave credence to claims that it will render congenitally short-statured children into normal size adults.
First discovered in 1921, HGH was isolated in 1956 and over the ensuing three decades its 191 amino acid sequence has been worked out, first by Genentech in 1986 and later by several other drug companies using recombinant DNA techniques.
Bio-engineered growth hormone can be produced in vast quantities by special bacteria or by mammalian cells. Previously, it had to be harvested form cadavers and was abandoned in 1987, because of a contaminating virus causing disease in the recipient similar to Mad Cow Disease, CJD.
The physiology of HGH is complex and the decline in production is age-related. It is secreted by the pituitary gland and causes growth and repair of the body's tissue through several mediations such as IGF-1.