The off-label use of human growth hormone (HGH) has spawned a multi-billion dollar industry. Some doctors see it as a fountain of youth, while others are staunchly opposed and fear that the risks far outweigh the potential benefits. The FDA has not approved the use of human growth hormone as an anti-aging therapy. Here, I’ll review what HGH is, how it works, and the pros and cons of use.
What is 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.
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.
Why not try it?
The biggest reason not to take HGH as an anti-aging therapy is simply that it has not been adequately studied. We do not know the risks and benefits of long-term use of HGH in healthy people. As we have learned from many other similar situations, such as the safety of long-term hormone replacement in menopause, we should not make any assumptions of benefit or safety about potent drugs or hormones. We should first do the correct studies, powered to look at real risks and benefits, not just short-term effects like changes in muscle. Only when large studies are completed should we consider treating large numbers of normal people. We should not be doing an uncontrolled experiment on millions of healthy people.
Should I be tested for growth hormone deficiency?
No. The syndrome of isolated growth hormone deficiency, without previous history of pituitary disease, is very rare. The testing is not 100%; the chance of a false-positive test is higher than the chance of the disease being real. If there is a high suspicion for HGH deficiency, at least two formal tests should be performed to reduce the chance of a false-positive result. The tests should include an insulin tolerance test and a GHRH-arginine test. These tests should only be performed by experienced clinicians, as they have some potential risk.
Who should use human growth hormone?
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.