growth hormone or somatotropin (sōmăt'ətrō`pən), glycoprotein hormone hormone, secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue.
..... Click the link for more information. released by the anterior pituitary gland pituitary gland, small oval endocrine gland that lies at the base of the brain . It is sometimes called the master gland of the body because all the other endocrine glands depend on its secretions for stimulation (see endocrine system ).
..... Click the link for more information. that is necessary for normal skeletal growth in humans (see protein protein, any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
..... Click the link for more information. ). Evidence suggests that the secretion of human growth hormone (HGH) is regulated by the release of certain peptides by the hypothalamus hypothalamus (hī'pəthăl`əməs)
..... Click the link for more information. of the brain. One such substance, called somatostatin, has been shown to inhibit the secretion of HGH. HGH is known to act upon many aspects of cellular metabolism, but its most obvious effect is the stimulation of the growth of cartilage and bone in children.

See also auxins auxin (ôk`sĭn), plant hormone that regulates the amount, type, and direction of plant growth.
..... Click the link for more information. (plant growth hormones).

Role in Dwarfism and Gigantism

A deficiency of growth hormone secretion before puberty (by the end of which the synthesis of new bone tissue is complete) results in pituitary dwarfism. Pituitary dwarfs, who can be as little as 3 to 4 ft (91–122 cm) tall, are generally well proportioned except for the head, which may be relatively large when compared to the body (this relationship of head to body is similar to that of normal children). Unlike cretins, whose dwarfism is caused by a deficiency of thyroxine thyroxine (thīrŏk`sēn), substance secreted by the thyroid gland .
..... Click the link for more information. , pituitary dwarfs are not mentally retarded; they are often sexually immature. They can be treated by injections of synthetic growth hormone, either somatrem or somatropin, which are produced by genetically engineered bacteria.

An excess of growth hormone in children results in gigantism; these children grow to be over 7 ft (213 cm) in height and have disproportionately long limbs. Excess growth hormone produced after puberty has little effect on the growth of the skeleton, but it results in a disease affecting terminal skeletal structures known as acromegaly acromegaly (ăk'rōmĕg`əlē)
..... Click the link for more information. .

Other Medical Uses

HGH has been used with some success to combat the weight loss and general wasting characteristic of AIDS and cancer. It is used illegally by bodybuilders and athletes to increase muscle mass. Controversy surrounds its use in normal children who simply want to be taller. In addition, a 1990 medical study that reported the reversal of many of the physiological effects of aging with regular injections of HGH has created a lucrative black market for it and has prompted funding of further trials. There has been no conclusive evidence, however, to support the use of HGH as an anti-aging treatment, and it can cause serious side effects, including diabetes, in older adults.

growth hormone (GH)

or somatotropin

Peptide hormone secreted by the anterior lobe of the pituitary gland. It promotes growth of bone and other body tissues by stimulating protein synthesis and fat breakdown (for energy). Excessive production causes gigantism, acromegaly, or other malformations; deficient production results in dwarfism, dramatically relieved if GH is given before puberty. Genetic engineering techniques now permit large-scale production of adequate amounts of GH for that purpose.