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The pituitary growth hormone in humans is a hormone that is released by the pituitary gland. Once released, this hormone affects human growth and muscle mass. By injecting it into a person who has a pituitary gland disorder, the hormone can be used to correct conditions such as dwarfism. Despite the benefits, the administration of pituitary growth hormone injections may also have side effects.
Once the hypothalamus secretes growth hormone releasing hormone (GHRH), the pituitary gland is stimulated to release pituitary growth hormone. This, in turn, stimulates many of the tissues in the body to grow and divide, particularly bone cells and skeletal muscle cells. In children whose growth plates have not yet closed, this causes the child to grow taller and develop skeletal muscle. In addition, pituitary growth hormone also stimulates the release of insulin-like growth factor 1, which also helps encourage muscle growth. The release of this hormone is regulated by the growth hormone inhibiting hormone (GHIH), which is believed to be released when the concentration of growth hormone reaches a certain level.
Every day, the pituitary gland releases pituitary growth hormone in waves. Often, the highest release occurs when a person sleeps. The amount of hormone released over a lifetime resembles a hill — starting low, building to a peak, and then dwindling. Teenagers often experience the highest amount of hormone release. In contrast, an elderly person may not produce the growth hormone at all.
Another effect of the pituitary growth hormone is its fat burning capabilities. When released, the hormone triggers the body to burn fat, rather than glucose, as an energy source, n order to save glucose. The hormone also stops cells from taking up glucose, leading to a rise in blood glucose levels. In addition, the mobilization of fat causes more fatty acids to be available in the blood. These effects are similar to that experienced by a person who has diabetes.
Deficiencies in the pituitary growth hormone can lead to many different disorders. In children, dwarfism, a condition in which the child may grow in normal proportions but may be abnormally short, may result. In adults, the effects may be muscle wasting, decreased strength, and a lower quality of life. There may also be an excess of the hormone, which can cause gigantism, a condition in which a child grows abnormally large. In adults and those whose growth plates have already closed, an excess of the hormone can result in the hands, feet, and face becoming too large.
Pituitary growth hormone injections may have many benefits, leading to its use — and sometimes abuse. These injections can be used to treat dwarfism in children. This treatment also can appeal, however, to body builders wanting to stimulate muscle growth, or to parents of an otherwise healthy child who may not be as tall as the parents would like. In response to these and other cases of abuse, in 2003, the United States Food and Drug Administration (FDA) approved the hormone’s use for boys who are not expected to grow taller than 5 feet 3 inches (about 1.6 meters) and girls not expected to exceed 4 feet 11 inches (about 1.5 meters). Use of these injections must be prescribed by a medical professional.