What is Growth Hormone (hGH)?
Growth Hormone is a protein, a string of 191 amino acids , that is produced in the pituitary gland of the brain. It is not a steroid.
hGH is released from the pituitary in pulsatile waves lasting minutes throughout the day, but the major amount is released at night during deepest sleep, when pulses last 1½ to 4 hours and are of greatest amplitude [2,3,4].
After hGH is released by the pituitary, it flows with the blood downstream to the liver, where it stimulates the production of another hormone, called Insulin-like Growth Factor-1 (IGF-1) .
It is IGF-1 that causes a majority of the beneficial effects associated with hGH .
Growth Hormone, like most hormones decrease with aging. “From young adulthood to midlife, GH secretion decreased by nearly 75%.” 
“Adults with growth hormone deficiency have increased fat mass, reduced muscle mass and strength, smaller hearts and lower cardiac output, lower bone density, and higher lipid concentrations. They also have decreased vitality, energy, and physical mobility; emotional lability; feelings of social isolation; and disturbances in sexual function, despite adequate correction of hormonal deficiencies other than growth hormone deficiency.” 
This constitutes a deficiency syndrome which is reversed by supplementation with recombinant human Growth Hormone .
The point of Bio-Identical Hormone Replacement Therapy is to recover lost function, and to thereby gain health benefit.
Since 1985, human Growth Hormone (hGH) has been produced using “recombinant DNA technology”. A specific strain of the bacterium, Escherichia coli, has been genetically modified to produce an exact copy of hGH [1,10].
The first reports that administration of hGH to older individuals provided increased quality of life were published in the New England Journal of Medicine in 1990  and the journal, Hormone Research, in 1991  both by lead author, Daniel Rudman, MD of the Medical College of Wisconsin.
Growth Hormone comes to public attention now and then because of some shocking revelation in the popular media concerning athletes or celebrities. In this way, hGH has gotten the reputation of being a substance that engenders abnormally superior physical performance in athletic endeavors, but has no other value.
I disagree with such a shallow, sensationalistic point of view. The hype serves to hide the reality. It casts an illusion.
Supplementation with Growth Hormone, along with the other hormones of youth, plus nutrition and exercise, altogether provide enhanced quality of life during the aging process. And, that is the point of the original Rudman articles.
Growth Hormone is involved with growth early in life, as you might imagine, but also healing. My hormone teacher, Neal Rouzier, MD, has consistently referred to Growth Hormone as “Healing Hormone”, a substance promoting repair .
As well, “A key systemic regulatory hormone is growth hormone (hGH), which has a developmental role in virtually all tissues and organs.” 
“Growth hormone affects somatic growth, sexual maturation, body composition and metabolism, as well as aging and longevity.” 
It’s important to remember that a hormone is a substance naturally produced in the body that takes messages to other parts of the same organism. To emphasize, the term “hormone” should be reserved for signaling substances naturally produced in the body. Pharmaceuticals that are not produced in nature but attach themselves to hormone receptor sites should not be referred to as “hormones”.
Thus, if a low level of a hormone is measured in the body, supplying additional amounts to produce an optimal, youthful level is “supplementation.” Giving an unnatural pharmaceutical does not resolve any deficiency.
As well, taking excess amounts of a natural hormone that is way above what is seen in youth is in itself, unnatural, and can cause harm.
It is true that at least some elite athletes are using excessive, supra-physiological amounts of hGH for purposes of enhancing athletic performance. And I am not advocating that kind of irresponsible and dangerous activity.
I am advising restoration to youthful levels for the purpose of health benefit.
How is hGH administered?
“Growth hormone is administered subcutaneously once a day, titrated to clinical symptoms, signs and IGF-1.”  It is given, usually at bedtime, very similar to the way insulin is taken.
Since hGH is a protein, it cannot be taken by mouth.
“For adults, GH replacement therapy should be initiated at a low dose, followed by individualized dose titration while monitoring patients' clinical status and serum insulin-like growth factor-I (IGF-I) concentrations.”  The IGF-1 level is a simple blood test.
The usual adult dose is 0.4 mg per day, but it is a good idea to start with 0.1 or 0.2 mg per day, and titrate the dose upward slowly. This precaution is especially important in the elderly.
What are the side effects?
Elevated blood sugars and insulin resistance can occur for the first 3 to 18 months or so, then normalize. So, people checking their blood sugars can notice a temporary change. Long term studies show no increase in the occurrence of diabetes while taking hGH [23,24].
Swelling ankles, usually mild, can occur. This is due to water retention, usually resolving after decreasing dose and/or lifestyle intervention, like diet and exercise [6,8,15].
The most problematic side effect, in my experience, is joint pain, usually in an elbow, but sometimes a knee, which subsides after reducing the dose. As well, pain in the wrists can occur, mimicking carpal tunnel syndrome. Again, the best way to deal with such pain is to start off with a very low dose, then slow raise it over several weeks time .
Occasionally, a patient will be very vulnerable to this consequence and will have generalized joint pain. This miserable situation is usually caused by starting off at the full dose. Again, the fix is to discontinue the hGH, let the joint pain subside, then restart with a very low dose.
I have had some patients tell me that they notice no positive feelings that they would ascribe to taking the hGH. I guess you could call that a sort of side effect. They may be having health benefit, but have not noticed good sensations or emotions.
This may be especially disconcerting for patients who felt more energetic, positive, and upbeat after Armour Thyroid or Testosterone, or in the case of women, Estradiol and Progesterone.
I expect patients to feel free to bring any of their concerns regarding hormone supplementation to me for discussion at any time.
Does hGH increase lifespan?
There is no proof of that. “A variety of favorable effects of GH replacement have been indicated; however, it has not yet been established fully whether there is a direct effect of GH treatment on reducing mortality.” 
“By contrast, several mutations that decrease the tone of the GH/IGF-1 axis are associated with extended longevity in mice.”  Many current observational studies (of mice) in the scientific literature are saying that: “Available evidence indicates that reduced GH signaling is linked to extended longevity.” 
Again, opposite opinions are garnered from “associative” vs “interventional studies.”
Does hGH or any B-HRT reverse aging?
Many patients have told me that they feel much better taking natural hormones. They notice increased energy, sociability, and beneficial changes of physical appearance. There are salutary changes of lipids and indicators of inflammation. Patients may feel younger. However, this does not reflect a reversal of a cellular, genetic, or biochemical mechanism which we may postulate as the “aging process” itself.
Does everybody notice benefit from B-HRT?
No. In medicine, we know that no treatment works for everybody.