Human growth hormone (hGH or GH) is a protein produced in the body that's important not only during childhood but also throughout adulthood. Growth hormone is produced by the pituitary gland, which is known as the "master gland" because it secretes many hormones that control the actions of other glands. A part of the brain called the hypothalamus sends signals to the pituitary gland to produce GH, which then travels through the bloodstream to function in other parts of the body.
Although scientific research usually focuses on the role of GH in the growth process, its contribution to adult metabolic processes is also crucial.
As most of us know, many factors influence growth. Good nutrition and overall health affect growth, as do hormones in the body such as GH. However, GH is not the only hormone involved in the growth process. Other pituitary hormones — including thyroid-stimulating hormone, adrenocorticotropic hormone, luteinizing hormone, and follicle-stimulating hormone — affect growth indirectly by acting through other glands. Although all of these hormones can influence growth, GH is the major growth regulator in the body.
The primary job of GH in childhood is to stimulate bone and tissue growth. GH stimulates the epiphyseal growth plates in the bone, which are responsible for bone elongation. GH also triggers the release of the insulin-like growth factor-I (IGF-I) protein, which stimulates the growth of bone, muscle and other tissues in response to GH and also, in turn, regulates GH release from the pituitary. Growth hormone also contributes to proper bone density, which is important in both childhood and adulthood, when poor bone density can lead to problems such as osteoporosis.
This mechanism, in conjunction with other complex body processes, maintains the growth of the human being from infancy through adulthood.
Although GH's main function is to promote growth in childhood, GH is still important once adulthood is reached. In adults as well as in children, GH helps regulate metabolism — a critical chemical process through which the body turns food into energy, tissue or waste products. GH assists in transporting molecules, conserving sugars, building proteins, and breaking down fats. Not only is the GH produced in your body vital to maintaining healthy body composition, it also contributes to proper bone density, heart muscle function, and ratios of "good" to "bad" cholesterol, all of which are important to reduce the risk of such conditions as high cholesterol and osteoporosis.
Thus, like children, adults also need to maintain adequate levels of GH in the body. Without sufficient GH, adults have an increased risk of developing serious health problems, such as cardiovascular disease and bone disease, later in life.