Growth hormones are the chemical stimulation that initiates cell division, bone growth, and a number of other physical processes within the human body. The nature and impact of growth hormone released from the anterior pituitary gland, often referred to as the "master gland" of the body, is uniquely determined within every individual. Deoxyribonucleic acid (DNA) provides the governing code to human genetic structure. The manner in which DNA is organized within the human gene is the blueprint for how the growth hormone will tend to impact on the physiological processes of the body.
While the growth hormone is a crucial component of physical development in the childhood and adolescence of all humans, the body depends on the regulatory effects of this chemical for its entire lifetime. Growth hormone is the term used to describe the natural chemical produced by the body; the synthetic form of the growth hormone is identified by the acronym HGH.
The human growth hormone (HGH), also referred to as somatotropin, is released from the pituitary gland as a polypeptide, a collection of 191 amino acids that are the essential components of proteins, and used by the body to build and maintain muscle, organs, and tissue. While the growth hormone is released in various forms from the pituitary, referred to as sonatotrope cells, all are centered on a protein-developing capability. The pituitary gland, which regulates sexual reproduction and other developmental features, also produces and secretes other hormones; the growth hormone is the largest such production.
A number of external factors will influence the stimulation of or the reduction in the amount of growth hormone flowing from the pituitary gland at a given time. Circumstances that stimulate the pituitary include exercise, particularly when there is significance resistance involved in the activity, as in weight training, sleep, and the ingestion of dietary proteins such as meat or dairy products, or when the level of glucose in the blood system is low, a condition known as hypoglycemia. Factors tending to reduce pituitary growth hormone output are the ingestion of dietary carbohydrates, and the increased level of glucocorticoids such as prednisone and cortisone in the bloodstream.
Growth hormone secretion typically peaks at night, approximately one hour after the person has fallen asleep. The production of growth hormone is highest in the early childhood years, between the ages of three and six. The most pronounced peaks of hormone delivery to the body by the pituitary gland occur during adolescence, in the usual developmental spurts that accompany puberty. After age 20, production of growth hormone declines steadily; the amount of hormone produced at age 40 by the pituitary gland is approximately 40% of the level generated at age 20.
Growth hormones have a number of separate but related functions with respect to the performance of many bodily systems. During the periods of the body maturation from childhood through adolescence and into adulthood, the primary function of the hormones is to provide a building-up effect, through the stimulation of cells, that is accomplished by the interaction of the growth hormones and various types of protein receptors located on the surface of the cells.
The crucial areas of human growth and development that are either directed or influenced by the presence of growth hormone include the long skeletal bones, chiefly, the femur (thigh bone), fibula (lower leg), tibia (shin bone), and humerus (upper arm), through the stimulation of the physis (growth plate), which is present on all such bones near the epiphysis, or head, at each end of the bone, and the cartilage cells.
Growth hormones will in turn trigger the production of insulin-like growth factor 1, known as IGF-1, a chemical similar to insulin, the hormone produced in the pancreas in response to the elevated presence of sugar in the bloodstream. Insulin signals the liver to store greater amounts of glucose to reduce blood sugar levels. Growth hormones also trigger the increase of muscle mass, when the body is subjected to appropriate physical exercise. Growth hormones also cause the increased retention of the mineral calcium, and the specific mineralization of bone, particularly phosphorus, which is required for the construction of bone cells.
The health of various organ systems, including the renal system (kidneys), is affected by growth hormones, as is the promotion of lipolysis, the process by which fats ingested into the body through diet are reduced into their constituent fatty acids and glycerol and made useful as energy sources. Fatty acids can be employed as a direct source of fuel, in the creation of adenosine triphosphate (ATP); glycerol is processed by the liver into, and is ultimately stored as, glycogen.
Although rare conditions, both deficient and excessive amounts of growth hormone can cause serious health problems. The two major conditions of excessive amounts are acromegaly, which is the establishment of a slow developing, growth hormone-producing tumor that may remain hidden from detection, and pituitary giantism, which creates a super-accelerated bone and tissue growth. When the hormone is not released in large enough amounts, the person will experience reductions in physical size, strength, levels of energy, and often a reduced bone mass and density, known as osteoporosis.
Significant areas of interest regarding the uses of the human growth hormone have arisen since the late 1970s, which have consequently spurred scientific research. These areas of research include hormone treatments for growth hormone deficiency diseases; as a counter to the effects of weight loss caused by wasting diseases such as AIDS and cancers; as a supplement to those persons in their adolescent years who wished to grow taller; as a possible means to reverse the natural aging process; and as a training aid and supplement to athletes engaged in power and strength-dominated sports.
Much of the research has been conducted with respect to athletic performance, given the significant commercial rewards for both a successful developer of a growth hormone supplement and for any athlete who might derive the corresponding athletic benefits. When the human growth hormone became the subject of intense scientific research in relation to its potential use as a nutritional supplement, particular emphasis was placed upon those sports in which physical size and strength are at a premium. In the 1980s, reports began to circulate, often unsubstantiated, that various bodybuilders, weightlifters, and professional American football players had experimented with growth hormones.
The growth hormone has been available in a synthesized form for over 20 years, where it is widely distributed in both North America and Europe as HGH; the first human growth hormone made available for non-medical purposes had been extracted from the pituitary glands of cadavers, to be either taken in pill form or injected into the bloodstream. A wide range of scientific studies have confirmed that in its natural as well as in its synthetic form, human growth hormone will tend to stimulate an increase in physical strength and endurance of an athlete, when combined with a focused strength training program. The natural and synthetic forms of the hormone stimulate the liver to produce IGF-1, which has an established dual effect of stimulating the production of myoblasts, a key to the development of muscle growth, as well as facilitating cartilage and bone cell growth, in addition to its increased lipolysis effect. The additional human growth
The period within which human growth hormone has been examined scientifically is relatively short, and much of the use of both natural hormone and HGH has occurred in clandestine circumstances; definitive conclusions regarding the safety of its use as an athletic nutritional supplement are not yet available. It is well known that in the early days of HGH use, the hormone was often a part of a larger mixture of substances, including anabolic steroids; the effects of these substances in combination are a focus of physical study. However, growth hormone undoubtedly possesses significant potential as a performance-enhancing substance, and for this reason it is a prohibited substance in elite athletics of all types.
Human growth hormone in supplement form is specifically listed as a prohibited substance by the World Anti-Doping Agency (WADA). WADA is often a secretive agency with regard to how tests for certain prescribed substances are conducted, to ensure that a user of a banned substance does not enlist as yet undiscovered means to mask or otherwise defeat the testing procedures. Substances such as growth hormone, both as a natural and synthetic product, cannot usually be detected in the bloodstream or urine of an athlete.
The testing developed for human growth hormone in international athletics will center upon the presence of other related particles in the blood. Such particles are often known as metabolites. Growth hormone produces elevated levels of IGF-1 in the bloodstream, in measurable amounts after each dosage. It is the discovery of such metabolites that will be the key to detecting the usage of HGH by athletes.