April, 2007

Growth Hormone Use in Adults
By Kim M. Norton
Today’s Dietitian
Vol. 9 No. 4 P. 50

A recently approved hormone therapy can improve heart contractibility, reduce the effects of osteoporosis, and increase a person’s overall quality of life.

In 1996, growth hormone replacement therapy (GHRT) was approved for use in adults with a growth hormone deficiency (GHD). Since that time, there has been considerable interest in what GHRT can do for adults with clinically diagnosed GHD.

Recent research into GH use in adults has produced tangible results. Patients have increased muscle mass, decreased fat content, improved bone density and mood, lowered cholesterol, strengthened heart function, and increased quality of life. “Everything about the use of GH in adults is positive,” says Norman Lavin, MD, an endocrinologist in Tarzana, Calif., who has been using GH for the past five years to treat adult patients with a deficiency.

“GHRT has historically been used in patients with panhypopituitarism [pituitary gland produces no GH] or hypopituitarism [pituitary gland does not produce enough GH]. But as a person ages, somatopause, or a growth-pause, occurs between age 40 and 50, [when] there is a natural decline in growth hormone production,” says Lavin. When a 60-year-old patient feels like a 90-year-old, GHRT can drastically improve not only their quality of life but also their overall health, he adds.

When the FDA approved GH for use in adult patients with GHD, the only approved indication was pituitary disease from known causes, including pituitary tumor, pituitary surgical damage, hypothalamic disease, irradiation, trauma, and reconfirmed childhood GHD. Most patients considered for GH therapy are in one of these categories, according to an article in Endocrine Practice.

“A few patients with definite GHD, however, have other kinds of pituitary-hypothalamic disease. These include patients with Sheehan’s syndrome, autoimmune hypophysitis, or hypophysitis associated with other inflammatory conditions such as sarcoidosis. Most adults selected for GH therapy should have an easily recognized cause, clear-cut clinical features of the adult syndrome, and nonrefutable laboratory evidence of GHD. Such patients clearly have GHD and would most likely benefit from GH replacement therapy,” the article states.

The unfortunate part of GH use in adults is the misuse of it by so-called “antiaging” specialists, says Gary Pepper, MD, FACP, an endocrinologist with the Palm Beach (Fla.) Diabetes and Endocrine Specialists. “Marketing is destroying a good thing and is preying on people’s gullibility with promises of eternal youth through the use of growth hormone creams and pills,” he says.

Some antiaging clinics are claiming to use GH to improve skin tone, reduce fatigue, decrease body mass, and increase muscle mass. “Growth hormone is not a panacea; if the patient is producing an adequate amount of GH, more will not make a considerable difference,” Pepper says.

At this time, the only effective and approved method of application for GH is through injections. Creams and pills are not GH; this represents the delineation between medicine and marketing, according to Pepper.

Symptoms and Diagnosing
Darwin’s Theory of Evolution found through natural selection that older organisms make way for newer and better organisms. It is for this reason that the human body naturally slows its production of GH due to “apoptosis, or programmed cell death.” Decreased production of GH is central to people’s ability to pass on their genetic code. Once people reach a certain age, their genetic code is subpar and not essential for the evolution of the human race, says Pepper.

As GH levels naturally decline, the functioning parts of the body begin to decline as well. However, should a patient show signs and symptoms of a GHD due to a disorder in the pituitary gland, it is necessary to replace what nature is no longer providing. That being said, Pepper, along with the other experts, are not advocates of the cosmetic use of GH to improve skin, muscle tone, or performance; they only deem its use necessary if a pituitary tumor or disorder is present.

In children, GH is most often associated with linear growth, says Patricia D. Costa, the executive director of the Human Growth Foundation in Glen Head, N.Y. For adults, however, linear growth is not the issue. Instead, adults with GHD are fraught with symptoms they may consider signs of old age, including lack of energy, fatigue, muscle weakness, weight gain, sleep problems, and decreased libido.

On the psychological side, they may exhibit shyness, withdrawal, nervousness or anxiety, feelings of sadness or depression, and a sense of hopelessness. “An examination of the pituitary gland could find a growth hormone deficiency. In these patients, GHRT could make a tremendous difference in their lives,” Costa says.

Because GHD symptoms may mimic that of old age, an endocrinologist must determine the patient’s GH production. Several GH tests stimulate the pituitary gland beyond what it normally produces. These include the use of or a combination of insulin, arginine, clonidine, glucagon, and levodopa. Another necessary screening test is the insulin-like growth factor (IGF-1), which determines the concentration and adequacy of GH production, according to the American Association of Clinical Endocrinologists (AACE).

There is some debate as to what constitutes a GHD, but the AACE says, “A peak value of less than 5 [micrograms per liter] after stimulation indicates a growth hormone deficiency. Without clear diagnostic and clinical evidence of GHD, the patient will not be eligible for GHRT.” A GH reading of greater than 5 [micrograms per liter] appears to be the standard definition of abnormal, but for some, that determination can be as low as 3 [micrograms per liter], explains Susan Smith, RN, CDE, CNS, PNP, director of medical education for the Magic Foundation in Oak Park, Ill.

“If a patient shows a level of 4.8 [micrograms per liter] of GH, it is generally recommended that [the patient] undergo an MRI [magnetic resonance imaging scan] to discover or rule out any abnormalities within the pituitary gland. GHRT is not something to dispense lightly; great care should be taken before beginning treatment,” she says.

GH Dosages
GHRT should begin once it has been determined that a patient has definitive clinical evidence of a pituitary disorder resulting in decreased GH production. “It is our experience that a patient beginning treatment should start with a low dose to monitor adverse reactions closely,” Smith says. The usual starting dose is between 0.1 and 0.3 milligrams per day, with doctors assessing their patients monthly and titrating the usual daily doses in increments of 0.1 to 0.2 milligrams per day to the predetermined end point, according to the AACE guidelines.

For some, GHRT may become a permanent part of their life; for others, a finite treatment regimen may be all that is necessary, explains Lavin. “In my practice, I will administer GH on a short-term basis at a certain dosage until the patient has improved their cholesterol, muscle strength, and their general well-being has returned. Once this has been achieved, I will reduce their dosage to a maintenance level with treatment lasting one to two years,” he says.

Before administering the first dose of GH, it is imperative to consider the patient’s age as a determining factor in the susceptibility of side effects, according to the AACE. The AACE’s guidelines for dosages are as follows:

• younger patients require higher doses;

• women require more than men;

• higher doses are needed for oral vs. transdermal or endogenous administration in women taking estrogen;

• the presence of side effects necessitates that dose be reduced; and

• transition patients (discontinued GHRT for childhood indications and are being considered for adult GHRT) require the highest dose.

While the patient is undergoing treatment, the physician must exercise good clinical judgment by assessing side effects, serum IGF-I levels, and changes in body composition to determine the appropriate maintenance dose. “Serum-free thyroxine and lipid levels should be assessed initially and at six to 12 months,” the AACE advises.
The long-term effect of GH use in adults is not yet completely known, says Lavin. “This is a relatively new treatment in adults, so we do not know what we will discover about GH use in 10 or 20 years,” he says.

Side Effects
Expected side effects when beginning GHRT include transient headaches, muscle aches, and tissue swelling in the hands and feet, according to Lavin. “I generally advise my patients to take an over-the-counter pain medication, and if the side effects persist, I will alter the GH dosage to reduce the side effects,” he says.

With the limited information available on GH use in adults, some have raised concerns about its link to cancer. “If you have a patient with cancer, I would advise against introducing GH into their system. Although there is no link between GH use and cancer at this time, it is in fact a growth hormone. We do not know what we will find in the future,” says Pepper.

“Keep in mind that when introducing growth hormone into the system, there is always the possibility that it can grow some bad things. Nothing has been proven as of yet, but this is a relatively new treatment that should be administered with care and only for as long as necessary,” says Lavin.

Further Information and Support
It appears GH has been in the public eye for much longer than the five or six years that endocrinologists have been using it for treatment. Athletes have been taking hormones to improve their bodies, and antiaging clinics are touting GH as a cure-all for the aging process.

With limited and false information circulating, it is important to realize that feeling depressed or fatigued is not a GHD symptom. Lavin and Pepper agree that what was a critical and valuable approval by the FDA for those adults diagnosed with GH deficiencies has become tainted by infomercials, unrealistic promises, and fallen sports heroes.

“An important point to convey to doctors is that it is currently necessary to have a legitimate cause to treat an adult [with GH]. It is imperative to separate the cosmetic need from the medical need and to realize that the physician is probably a quack if he is using GH in anyone without a pituitary tumor or defect,” warns Pepper.

There are numerous resources available for both the public and healthcare professionals seeking more information on GHD and GHRT. The Magic Foundation has information available on its Web site for the numerous disorders that affect the pituitary gland in both children and adults. Another valuable resource is the Human Growth Foundation, which provides brochures about adult GHD and offers support groups and listservs for individuals and families dealing with the condition.

— Kim M. Norton is a New Jersey-based freelance writer specializing in healthcare-related topics for various trade and consumer publications.

Resources
American Association of Clinical Endocrinologists Medical Guidelines for Clinical Practice for Growth Hormone Use in Adults and Children—2003 Update. Endocr Prac. 2003;9(1):64-76.

Human Growth Foundation, www.hgfound.org

The Magic Foundation, www.magicfoundation.org