In 1513, the Spanish explorer Juan Ponce de Len arrived in Florida to search for the fountain of youth. If he got any benefit from his quest, it was due to the exercise involved in the search. Few men today believe in miraculous waters, but many, it seems, believe in the syringe of youth. Instead of drinking rejuvenating waters, they inject human growth hormone to slow the tick of the clock.
What is HGH ?
HGH means “human growth hormone”. Human growth hormone is a product of the pituitary gland, the master gland of the body. As the name implies, it promotes linear growth in children and adolescents. After the body stops growing taller, the levels of HGH decline quickly and often become very low in adult life. Many of the effects of HGH are brought about through a second hormone, insulin-like growth factor-1, made by the liver. HGH is given by daily injection, and is quite expensive. Alternative treatments, such as the nasal spray or pills to stimulate HGH release, have not been proven to have any benefit.
Why should HGH work as an anti-aging therapy?
HGH has effects on body composition, not just growth. People who have a significant HGH deficiency, generally due to pituitary disease, have increased body fat and decreased muscle mass and decreased bone density. These changes in HGH-deficient patients mimic aging. Interest in using GH to reverse these age-related changes in healthy adults dates to a study by Dr. Rudman and others published in 1990 in the New England Journal of Medicine. This study found that a small number of older men who were given HGH saw improved muscle mass, decreased body fat, and better bone density.
There have since been numerous claims that HGH is the “anti-aging miracle.” HGH has also been used by athletes to promote muscle mass, a practice that has banned by the World Anti-Doping Agency due to safety concerns.
Human growth hormone: Up close and personal
Growth hormone (GH) is a small protein that is made by the pituitary gland and secreted into the bloodstream. GH production is controlled by a complex set of hormones produced in the hypothalamus of the brain and in the intestinal tract and pancreas.
The pituitary puts out GH in bursts; levels rise following exercise, trauma, and sleep. Under normal conditions, more GH is produced at night than during the day. This physiology is complex, but at a minimum, it tells us that sporadic blood tests to measure GH levels are meaningless since high and low levels alternate throughout the day. But scientists who carefully measure overall GH production report that it rises during childhood, peaks during puberty, and declines from middle age onward.
GH acts on many tissues throughout the body. In children and adolescents, it stimulates the growth of bone and cartilage. In people of all ages, GH boosts protein production, promotes the utilization of fat, interferes with the action of insulin, and raises blood sugar levels. GH also raises levels of insulin-like growth factor-1 (IGF-1).
What are the actual results seen in research?
The largest review of trials with HGH demonstrate that long-term use of growth hormone caused an average 2.3 kilogram (about 5 lbs) loss of weight, 2.6 kg (5.6 lbs) loss of fat, 1.4 kg (3 lbs) increase in lean body mass, and no consistent change in bone density. Patients feel generally better, as seen in quality of life scores.
Sounds great. Shouldn’t everyone take it?
There are significant potential side effects to HGH therapy. Known side effects include increased swelling, joint pain, carpal tunnel syndrome, insulin resistance and increased risk of diabetes. The potential effect of HGH to promote cancer growth remains controversial. People who purchase HGH illegally may be getting tainted or impure products, which are potentially dangerous.
What is the effect on longevity?
The effect on longevity is not yet known. There is a paradox that both HGH deficiency and HGH excess, a disease called acromegaly, are associated with shorter life expectancy. Further, even though there is an increase in mortality in pituitary patients missing HGH, there is no evidence that this it improved with HGH treatment.
Who should use human growth hormone?
GH is available as a prescription drug that is administered by injection. GH is indicated for children with GH deficiency and others with very short stature. It is also approved to treat adultGH deficiency — an uncommon condition that almost always develops in conjunction with major problems afflicting the hypothalamus, pituitary gland, or both. The diagnosis of adult GHdeficiency depends on special tests that stimulate GH production; simple blood tests are useless at best, misleading at worst.
Adults with bona fide GH deficiencies benefit from GH injections. They enjoy protection from fractures, increased muscle mass, improved exercise capacity and energy, and a reduced risk of future heart disease. But there is a price to pay. Up to 30% of patients experience side effects that include fluid retention, joint and muscle pain, carpal tunnel syndrome (pressure on the nerve in the wrist causing hand pain and numbness), and high blood sugar levels.
Human growth hormone is approved for children with HGH deficiency or who have diseases that cause short stature (such as Turner’s syndrome), and adult patients with proven HGH deficiency, muscle wasting due to HIV, or short-bowel syndrome.
Recommended sources for additional information:
- The Hormone Foundation at www. Hormone.org
- Molitch M et al. Evaluation and Treatment of Adult Growth Hormone Deficiency an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism, June 2011, p1587-1609
- Liu H, et al. Systemic review: The safety and efficacy of growth hormone in the healthy elderly. Annals of Internal Medicine 2007, p104-115.
GH for aging
Among its many biological effects, GH promotes an increase in muscle mass and a decrease in body fat. As men age, GH levels fall. During the same time span, muscle mass declines and body fat increases. And so, the theory goes, the way to arrest these effects of aging is to inject GH.
Similar claims have been made for other hormones that decline with age, including testosterone and dehydroepiandrosterone (DHEA) in men, and estrogen in women. Research shows that estrogen replacement does more harm than good in older women, and there is no solid evidence that testosterone and DHEA are safe and effective for healthy older men. But that has not stopped the growth of “anti-aging” and “regenerative medicine” clinics and Web sites.
Expensive injections of growth hormone are offered by many practitioners, even though theFDA has not approved the use of GH for anti-aging, body building, or athletic enhancement, and the marketing or distribution of the hormone for any of these purposes is illegal in the U.S.According to one estimate, 20,000 to 30,000 Americans used GH as “anti-aging” therapy in 2004 alone; according to another, 100,000 people received GH without a valid prescription in 2002.
To evaluate the safety and efficacy of GH in healthy older people, a team of researchers reviewed 31 high-quality studies that were completed after 1989. Each of the studies was small, but together they evaluated 220 subjects who received GH and 227 control subjects who did not get the hormone. Two-thirds of the subjects were men; their average age was 69, and the typical volunteer was overweight but not obese.
The dosage of GH varied considerably, and the duration of therapy ranged from two to 52 weeks. Still, the varying doses succeeded in boosting levels of IGF-1, which reflects the level ofGH, by 88%.
As compared to the subjects who did not get GH, the treated individuals gained an average of 4.6 pounds of lean body mass, and they shed a similar amount of body fat. There was a slight drop in total cholesterol levels, but no significant changes in LDL (“bad”) cholesterol, HDL(“good”) cholesterol, triglycerides, aerobic capacity, bone density, or fasting blood sugar and insulin levels. But GH recipients experienced a high rate of side effects, including fluid retention, joint pain, breast enlargement, and carpal tunnel syndrome. The studies were too short to detect any change in the risk of cancer, but other research suggests an increased risk of cancer in general and prostate cancer in particular.