Human growth hormone


Human growth hormone (HGH or GH), also known as somatotropin, is a protein hormone naturally synthesized and secreted by the anterior pituitary gland, which stimulates growth and cell reproduction. During adolescence production of HGH is generally high. HGH levels peak somewhere between the ages of 21 and 30 and then decline when a person is in his or her 40s.
The identification, purification, and later synthesis of growth hormone are associated with Choh Hao Li, a Chinese biologist and biochemist living from 1913-1987.
By the middle of the 20th Century, endocrinologists gained a better understanding of the clinical features that define growth hormone deficiency. GH is a protein hormone, like insulin, which had been purified from pig and cow pancreases for treatment of type 1 diabetes since the 1920s. However, similar attempts to use pig and cow sources of GH did not work as well in humans due to greater species-to-species variation of molecular structure.
From 1960 to 1985, growth hormone was extracted from human pituitary glands and given to children who did not naturally produce enough of the hormone. In 1985 the use of growth hormone from human cadavers was associated with the development of Creutzfeldt - Jakob disease (a rare, usually fatal disease of the brain, characterized by progressive dementia and gradual loss of muscle control, that occurs most often in middle age and is caused by a slow virus), and was withdrawn from use.
GH is now produced synthetically and given to both children and adults for a variety of reasons, most often involving deficiencies of the hormone. In the last two decades, GH has also been used to enhance growth in children and adults for reasons besides growth hormone deficiency, such as HIV-associated muscle wasting or organ transplant.
As of 2004, GH has been approved by the United States (US) Food and Drug Administration for treatment of many types of short stature. As of 2005, synthetic growth hormones available in the United States included: Nutropin® (Genentech), Humatrope (Lilly), Genotropin® (Pfizer), Norditropin® (Novo), and Saizen® (Serono). The products are nearly identical in composition, efficacy, and cost, varying primarily in the formulations and delivery devices. In 2005 an Israeli company, Teva, offered Tev-Tropin in the US at a lower price. Lilly and Alkermes are developing an inhalable version that is in phase III clinical trials as of 2006.
Currently, some adults are turning to shots of growth hormone in hopes to stop aging, even as its effectiveness and safety remain unproven. Growth hormone has also been occasionally misused by athletes hoping to increase strength or muscle mass.

Related Terms

Acromegaly, Genotropin®, GH, GHRH, growth hormone, growth hormone deficiency, growth hormone-releasing hormone, HGH, Humatrope, natural sequence GH, Norditropin®, Nutropin®, recombinant growth hormone, rhGH, Saizen®, somatotropin, somatropin, Turner syndrome.