GH also stimulates production of insulin-like growth factor 1 (IGF-1) and increases the concentration of glucose and free fatty acids.

GH is a 191-amino acid, single-chain polypeptide that is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.

In recent years in the United States, some health care providers are prescribing growth hormone in the elderly to increase vitality.

Blood tests conducted by WADA at the 2004 Olympic Games in Athens, Greece, targeted primarily HGH.

GH, human chorionic somatomammotropin, and prolactin belong to a group of homologous hormones with growth-promoting and lactogenic activity.

The major isoform of the human growth hormone is a protein of 191 amino acids and a molecular weight of 22,124 daltons.

[citation needed] Secretion of growth hormone (GH) in the pituitary is regulated by the neurosecretory nuclei of the hypothalamus.

[13] Somatotropic cells in the anterior pituitary gland then synthesize and secrete GH in a pulsatile manner, in response to these stimuli by the hypothalamus.

[14] Maximal secretion of GH may occur within minutes of the onset of slow-wave (SW) sleep (stage III or IV).

Accompanying problems can include sweating, pressure on nerves (e.g., carpal tunnel syndrome), muscle weakness, excess sex hormone-binding globulin (SHBG), insulin resistance or even a rare form of type 2 diabetes, and reduced sexual function.

[48] Major manifestations of GH deficiency in children are growth failure, the development of a short stature, and delayed sexual maturity.

In adults, somatomedin alteration contributes to increased osteoclast activity, resulting in weaker bones that are more prone to pathologic fracture and osteoporosis.

[49] Other adult causes include a continuation of a childhood problem, other structural lesions or trauma, and very rarely idiopathic GHD.

[citation needed] One version of rHGH has also been FDA approved for maintaining muscle mass in wasting due to AIDS.

[56] At the conclusion of the study, all the men showed statistically significant increases in lean body mass and bone mineral density, while the control group did not.

[60] A Stanford University School of Medicine meta-analysis of clinical studies on the subject published in early 2007 showed that the application of GH on healthy elderly patients increased muscle by about 2 kg and decreased body fat by the same amount.

[citation needed] GH has also been used experimentally to treat multiple sclerosis, to enhance weight loss in obesity, as well as in fibromyalgia, heart failure, Crohn's disease and ulcerative colitis, and burns.

GH has also been used experimentally in patients with short bowel syndrome to lessen the requirement for intravenous total parenteral nutrition.

[citation needed] In 1990, the US Congress passed an omnibus crime bill, the Crime Control Act of 1990, that amended the Federal Food, Drug, and Cosmetic Act, that classified anabolic steroids as controlled substances and added a new section that stated that a person who "knowingly distributes, or possesses with intent to distribute, human growth hormone for any use in humans other than the treatment of a disease or other recognized medical condition, where such use has been authorized by the Secretary of Health and Human Services" has committed a felony.

[55] This section has also been interpreted by some doctors, most notably[63] the authors of a commentary article published in the Journal of the American Medical Association in 2005, as meaning that prescribing HGH off-label may be considered illegal.

[65][67] In a 2012 article in Vanity Fair, when asked how HGH prescriptions far exceed the number of adult patients estimated to have HGH-deficiency, Dragos Roman, who leads a team at the FDA that reviews drugs in endocrinology, said "The F.D.A.

Typical ingredients include amino acids, minerals, vitamins, and/or herbal extracts, the combination of which are described as causing the body to make more GH with corresponding beneficial effects.

[74] In the United States, it is legal to give a bovine GH to dairy cows to increase milk production, and is legal to use GH in raising cows for beef; see article on Bovine somatotropin, cattle feeding, dairy farming and the beef hormone controversy.

[77] Several companies have attempted to have a version of GH for use in pigs (porcine somatotropin) approved by the FDA but all applications have been withdrawn.

[citation needed] Prior to its production by recombinant DNA technology, growth hormone used to treat deficiencies was extracted from the pituitary glands of cadavers.

[79] Very limited clinical studies of growth hormone derived from an Old World monkey, the rhesus macaque, were conducted by John C. Beck and colleagues in Montreal, in the late 1950s.

[80] The study published in 1957, which was conducted on "a 13-year-old male with well-documented hypopituitarism secondary to a crainiophyaryngioma," found that: "Human and monkey growth hormone resulted in a significant enhancement of nitrogen storage ... (and) there was a retention of potassium, phosphorus, calcium, and sodium. ...

[81] In 1985, unusual cases of Creutzfeldt–Jakob disease were found in individuals that had received cadaver-derived HGH ten to fifteen years previously.

[citation needed] As of 2005, recombinant growth hormones available in the United States (and their manufacturers) included Nutropin (Genentech), Humatrope (Lilly), Genotropin (Pfizer), Norditropin (Novo), and Saizen (Merck Serono).