Should Adults Receive Growth Hormone Treatment?

The controversy surrounding growth hormone use in adults deepens. Recent editorials in the prestigious New England Journal of Medicine have taken a negative view of growth hormone supplementation for adults. Dr. Mary Lee Vance comments, “general use (sic- of growth hormone therapy in adults) now or in the immediate future is not justified.”

My medical practice has recently received a letter from a major health insurer, United Health Care, stating that growth hormone use in adults will no longer be a covered medical therapy. When asked for justification of this curtailment of financial support for growth hormone therapy health insurers are certain to point to comments from experts such as Dr. Vance.

One of the reasons for the backlash against growth hormone therapy is the explosive proliferation of individuals and companies promoting their own propriety brands of growth hormone substitutes and so-called growth hormone releasers. We receive 10 or more emails daily marketing growth hormone related products. Unfortunately, most of the claims for these products are simply false or at best, unsubstantiated. Only injected prescription growth hormone made by major pharmaceutical companies can be expected to fulfill the goal of growth hormone supplementation. Making matters worse for supporters of growth hormone therapy in adults is that legitimate growth hormone products themselves can be abused for perceived benefits to athletic ability and cosmetic appearance.

Why all the fuss about growth hormone? Is it truly capable of making us stronger, leaner, more energetic, and happier? Dr. Vance and her colleagues point out the lack of large studies which provide the answers to these questions. There are, on the other hand, smaller studies showing improvements in bone density, lean body mass and measures of well being associated with growth hormone therapy. Because of the limited amount of large studies evaluating growth hormone use in adults can we still justify our use of the hormone? As a practicing endocrinologist I have to answer these questions so I can provide my patients with the best existing therapies for their problems.

What exactly is growth hormone? It is a protein based hormone made by the pituitary gland which circulates in our blood in abundant amounts during the first twenty years of our lives but levels then slowly decline as we get older. Growth hormone controls the liver’s production of IGF (insulin like growth factor), formerly known as somatomedin, which stimulates the growth of cartilage which in turn results in increasing size of our bones. Growth hormone also appears to play a role in maintaining muscle mass and probably has multiple functions within the central nervous system (the brain and spinal cord).

If growth hormone is so important to general health why do levels drop off as we age? The decline in growth hormone levels with aging is mirrored by a decline in a host of other critical substances which maintain our health, such as DHEA (from the adrenal gland). One possible reason for the drop in these beneficial substances is for the plain and simple purpose of promoting our aging and eventual death. The survival of our species requires the removal of the old genetic material (use) so it can be replaced by the new (and possibly improved) genetic material (our offspring). Aging and death are required by the laws of evolution and therefore our bodies are programmed to self-destruct. The decline in growth hormone may be one way to serve this purpose.

Growth hormone is expensive. A year’s supply may cost up to 10 thousand dollars making economics another key element in the growth hormone controversy. How can we justify spending this amount of money on everyone who wants to prolong their strength and vitality? Forget about justify, our economy simply can’t afford this expenditure. Who will then decide who gets growth hormone and who won’t? I don’t have the answer either.

In the face of controversy what would be a reasonable approach for the practicing physician to follow? The first principal is to administer growth hormone only to those fail to make a minimum acceptable quantity of the hormone. If a patient is suspected of having growth hormone deficiency based on their history and physical exam a check will be made of the level of morning growth hormone and IGF. If the growth hormone is in the low normal range (below 2) the next step is a stimulation test to see whether the pituitary gland can be forced to release its store of the hormone. There are several tests which stimulate the pituitary release of growth hormone but the simplest is to administer L-Dopa (a prescription drug formerly used to treat Parkinson’s disease) by mouth and measure growth hormone levels in the blood over the next 2 hours. If the level remains below 5, growth hormone deficiency can be diagnosed.

Growth hormone deficient adults are given significantly smaller doses of growth hormone as compared to children being treated to achieve normal height. Even at these lower doses impressive improvements in mood and energy can be achieved. It is hard to measure these effects but statements such as, “Growth hormone changed the quality of my life. The strength and energy I used to have is back in full”, have been use by patients to describe their results.”

What about side-effects from growth hormone treatment in adults? Minor joint pains, carpal tunnel like symptoms, headache, and traces of swelling at the ankle have been described. Unfortunately, experts such as those quoted in the New England Journal use ominous tones when referring to growth hormone side-effects or to the possibility of its causing cancer or cardiovascular disease. These warnings remain largely unsubstantiated by even small studies.

In my practice I generally follow a year or two of treatment with growth hormone followed by 6 months off, simply to defer to the possibility of accumulating negative effects of prolonged GH therapy. The medical community is still waiting the ultimate word on growth hormone therapy in adults but based on reputable studies and my own observations I will continue to offer this treatment to my patients who exhibit the signs, symptoms and blood test evidence of growth hormone lack. As with any medical treatment it is important for each individual to consult with their own physician before embarking on any course of therapy.

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