Growth Hormone is a polypeptide Hormone. This means it is composed of a long chain of amino acids, 191 to be exact. Under normal physiologic conditions, Growth Hormone is secreted by the anterior pituitary gland. This is a gland that lies at the base of the brain in a bony cavity called the Sella Turcica. In addition to Growth Hormone, the anterior pituitary also secretes prolactin, thyroid stimulating Hormone, luteinizing Hormone, follicle stimulating Hormone, and adrenal corticotropic Hormone. The secretion of Growth Hormone by the pituitary gland is initiated by the hypothalamus, another gland in the brain that lies right next to the pituitary. The hypothalamus initiates Growth Hormone secretion by secreting Growth Hormone releasing Hormone (GHRH); at the same time it stops secreting a Growth Hormone inhibitory Hormone called somatostatin. When somatostatin is turned off and GHRH is turned on, the pituitary will release Growth Hormone in bursts of activity. These bursts of Growth Hormone release occur primarily during deep stages of sleep, such as stage 3 and stage 4. Once released in the blood, Growth Hormone is very short lived. It is generally completely metabolized and gone within a half-hour. During that time, however, it manages to reach the liver and many other cells in the body, and induce them to make another polypeptide Hormone called Insulin-like Growth Factor One (IGF-1). It is really IGF-1 that travels around to the various tissues of the body to effect most of the benefits that we attribute to Growth Hormone. The secretion of Growth Hormone itself is regulated by a classic biofeedback loop. This means when levels of Growth Hormone in the blood reach a certain threshold, Growth Hormone stimulates receptors in the pituitary to stop further Growth Hormone secretion. It also stimulates receptors in the hypothalamus to stop GHRH and turn on somatostatin. IGF-1, which goes up in response to Growth Hormone, also feeds back on the pituitary and hypothalamus to help control Growth Hormone secretion. This is nature’s system of checks and balances to assure we don’t have too much of any one Hormone.
USES OF Growth Hormone
Growth Hormone was initially used for children of short stature who are Growth Hormone deficient, either because of an inactive pituitary, a tumor of the pituitary, or destruction of the pituitary by surgery or by radiation to remove a tumor. The other pituitary Hormones were replaced along with GH. Growth Hormone was used only until the children reached an acceptable adult height and then it was stopped because it was thought to be useful only for Growth. The other pituitary Hormones, however, which were thought to be more critical, were continued throughout adulthood. It wasn’t until much later that adult Growth Hormone deficiency was recognized to be a problem. It was discovered that adults who were deficient in Growth Hormone suffered from premature cardiovascular disease, reduced bone density, central obesity, decreased muscle mass, depressed mood, elevated levels of LDL (bad) cholesterol, slower wound healing, fatigue, poor exercise tolerance and poor immune function. At that point the use of Growth Hormone began in this unfortunate population, resulting in improvement of all of the above. It wasn’t until 1990, however, that the benefits of Growth Hormone and the treatment of normal aging were recognized. The most recent new use of Growth Hormone is for the treatment of AIDS Wasting Syndrome. This is the condition of weakness, fatigue, and loss of muscle mass in AIDS patients. Since we at Cenegenicsï¿½ specialize in metabolic and hormonal control of aging, we will limit this discussion to the use of Growth Hormone in the treatment of normal aging.
Somatopause is an extrapolation of the term “menopause.” Menopause is the condition in women whereby the ovaries atrophy and cease to produce the sex Hormones Estrogen, Progesterone and Testosterone. Somatopause signifies the gradual decline in Growth Hormone production by the adult pituitary gland in both men and women that begins at approximately age 30 and continues at a steady rate throughout life. The decline in Growth Hormone level that occurs with Somatopause is accompanied by deterioration in the structure and functional capacity of our body, which is ultimately devastating to the Human condition. In fact, there is absolutely no difference between the clinical signs and symptoms of aging and those of adult Growth Hormone deficiency described above. The late Dr. Daniel Rudman first described the benefits of Growth Hormone therapy in normal aging adults. Dr. Rudman published a landmark article in the New England Journal of Medicine on July 7th, 1990. In his article, Dr. Rudman showed that by putting healthy aging men on Growth Hormone for six months, he was able to decrease their body fat by 14.4%, increase muscle mass by 8.8%, increase skin thickness by 7.1%, and increase lumbar bone density by 1.6%. These exciting findings clearly inaugurated the movement to supplement Growth Hormone in healthy aging adults, which today is becoming commonplace.
The benefits of Growth Hormone use in somatopause which have been clearly documented in the medical literature include the following: a decrease in body fat, an increase in muscle mass, thickening of the skin with decreased wrinkling, improvement in the cholesterol profile, an increase in bone density, enhanced feeling of well being, a decrease in the waist to hip ratio (meaning fat is removed primarily from around the waist where it is associated with a high risk of coronary disease), improvement in aerobic capacity, enhanced immune function and a decrease in the frequency of illness. The changes that our patients at Cenegenicsï¿½ seem to be most pleased with are the elevation in mood, increase in energy level, improved sleep, decrease in body fat, increase in muscle mass and enhanced ability to handle adversity with confidence and optimism.
Side effects of Growth Hormone are generally mild and are largely associated with salt and water retention. The minority of patients that experience this typically complain of mild weight gain from water retention associated with a vague feeling of puffiness. This is sometimes accompanied by joint discomfort, particularly in the fingers, with a feeling of tightness when making a fist. Other joints may also become uncomfortable. Carpal Tunnel Syndrome is a well-known side effect of Growth Hormone that was more common in the early days when Growth Hormone was given in higher dose with lower frequency. Carpal Tunnel Syndrome is also a function of fluid retention, which causes water to accumulate in the closed carpal tunnel compartment of the wrist, compressing the median nerve. This results in numbness and tingling in the palm and fingers. These side effects are easily remedied by abstaining from Growth Hormone for about a week, and then resuming the treatment with a 20% dose reduction. Older patients are more subject to side effects and are generally started at a low dose of Growth Hormone than younger adults. Another potential side-effect of Growth Hormone is the elevation of blood sugar. Growth Hormone mobilizes body fat, causing our fat cells to break themselves down and release free fatty acids into the blood stream. These free fatty acids are energy molecules which can be taken up by organs and many of our organs to be used for energy. When our muscles are consuming free fatty acids as a fuel, they are far less interested in sugar, therefore they tend to resist the effects of insulin, and extract less sugar from the blood. At the same time, Growth Hormone can increase glucose output from the liver to the blood. This combination of effects can raise blood sugar and raise insulin levels, neither of which is good. Fortunately, this is only a problem in people who eat a diet high in sugar and starch, and do little exercise. At Cenegenicsï¿½ we teach our patients to eat a low glycemic diet (low in sugar and starch) and exercise regularly. The effect of our nutrition and exercise program in lowering blood glucose and insulin levels far outweighs the effect of Growth Hormone in raising glucose and insulin levels. The net effect in our patients, therefore, is the lowering of glucose and insulin levels. This is a very health-promoting benefit that prevents disease and extends life span.
Originally taken only from Human cadavers, and used only in children of short stature, Growth Hormone has had an interesting and controversial history. Fortunately, the understanding of its importance in adult physiology came at approximately the same time as recombinant DNA technology, which led to greater availability along with virtual safety. Soon after this, the comparison was made between Growth Hormone deficient adults and aging adults. Because of the tremendous similarities, Growth Hormone began to be used and soon gained great popularity in the treatment of normal aging. Growth Hormone is clearly useful and therapeutic in this regard as long as it is used in a carefully monitored, professionally managed program. Any Growth Hormone program must include proper nutrition and exercise with emphasis on a low glycemic diet.