Human growth hormone, often abbreviated hGH, is the main hormone that regulates human growth and development during childhood and adolescence. It is also called somatotropin or somatotropic hormone. In addition to regulating growth, hGH plays a role in bone development and in regulating the amount of glucose (a type of sugar) in the bloodstream. In full-grown individuals, hGH helps maintain muscle and decrease body fat. It is one of several hormones produced by the pituitary gland, a pea-sized gland that lies under the brain near the center of the skull. Hormones produced by glands in the brain and throughout the body control the secretion of hGH. An excess or deficiency of hGH causes abnormal growth and development. Because hGH is believed by some to promote muscle growth, its abuse has become a widespread problem in sports.
Excess hGH secretion usually results from a pituitary tumor. In growing children, excess hGH causes gigantism, a disorder in which the sufferer grows abnormally tall. Once a person stops growing—usually between the ages of 18 and 24—hGH can no longer increase height. However, excessive secretion of hGH in full-grown individuals may cause acromegaly, a progressive enlargement of bones in the face, feet, and hands. If untreated, acromegaly can lead to serious complications.
Children with a growth hormone deficiency grow more slowly than normal and may not reach their full potential height. They may also suffer hypoglycemia (low blood sugar) and have increased body fat. Adults with hGH deficiency may feel less energetic and may have higher blood cholesterol levels. Physicians usually discover growth hormone deficiency while evaluating or treating related medical conditions. They can conduct specialized tests to confirm the diagnosis.
Physicians treat patients deficient in growth hormone with hGH injections. In the past, doctors obtained hGH from the pituitary glands of corpses. Since the 1980’s, physicians have used synthetic hGH, also called recombinant hGH, produced in a laboratory. Synthetic hGH has the same chemical structure as that produced by the body. The United States Food and Drug Administration (FDA) has approved synthetic hGH for treating several medical conditions, including growth hormone deficiency and abnormally short stature in children. However, synthetic hGH therapy remains expensive.
Human beings produce growth hormone throughout their lives, but the amount produced generally decreases with age. Some health practitioners believe that synthetic hGH can slow or reverse the effects of aging in adults. However, scientific research on these claims remains incomplete, and most scientists strongly doubt that hGH should be used as an antiaging therapy.
Many medical experts believe that synthetic hGH is widely abused by athletes to increase muscle and enhance performance in sports. The International Olympic Committee, the organization that oversees the Olympic Games, and most professional sports leagues have banned the use of hGH. However, because hGH occurs naturally in the body, regulators can have difficulty determining if an athlete is taking synthetic hGH to enhance performance. Scientific tests have not yet established the performance-enhancing qualities of synthetic hGH, and medical experts worry that using the drug in this way may have dangerous side effects. In the United States, federal law prohibits the distribution of hGH for antiaging or sports doping purposes.
See also Doping ; Dwarfism (Causes) ; Giant ; Hormone ; Pituitary gland .
