Human Growth Hormone

Human Growth Hormone (HGH) and Adult Growth Hormone Deficiency

Growth hormone (GH or hGH) 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).

It is normal for GH levels to decline as a person reaches adulthood, but new research suggests that some adults may have too low a level. Low levels of GH are linked to poor immune system, poor muscle tone, increase body fat, low energy levels, and cardiovascular changes, cholesterol and memory issues. GH insufficiency is associated with pituitary gland problems, brain injury, autoimmune disorders, and nervous system conditions.

Synthetic human growth hormone was developed in 1985.  Growth hormone, also known as somatotropin or somatropin, is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. It is a type of mitogen which is specific only to certain kinds of cells. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland. Growth hormone is not a steroid as many media outlets suggest. Growth Hormone works as a “repair” hormone. To take full advantage of HGH, balance and correct your other hormones first.

A better term for GH would be healing or repair hormone. Growth hormone is naturally produced by our pituitary gland and is essential for bone and organ growth in our youth. Although hGH is no longer needed for growth after reaching adulthood, hGH is essential for many other vital functions, and the significantly lowered levels seen as we age are correlated with everything from diminished energy, cardiovascular disease, increased body fat, decreased muscle mass, and more.

Growth hormone diminishes rapidly after the age of 30. It is found that growth hormone deficient patients have almost 50% higher rate of death from heart disease than those with more optimal levels. In a 1990 New England Journal of Medicine article, Dr. Rudman reported on his study with the use of human growth hormone in elderly veterans.

“The effects of six months of human growth hormone on lean body mass and adipose tissue reversed the equivalent of changes incurred during 10-20 years of aging. The overall deterioration of the body that comes with growing old is not inevitable…We now realize that some aspects of it can be prevented or reversed.”   – Dr. Daniel Rudman, MD – New England Journal of Medicine

In 1999, the National Institute on Aging completed another landmark study that was designed to either refute or substantiate the results of Dr. Rudman and also to extend his study by measuring other parameters. This was a double-blind, placebo-controlled, multi-center trial in both men and women with a large number of patients. This study involved not only growth hormone but also the estrogen, progesterone and testosterone. This study not only confirmed the benefits of growth hormone, but also demonstrated that the addition of estrogen/progesterone and testosterone improved the effectiveness of growth hormone.

After 6 months treatment of 0.75 I.U./day here are the percent of patients reporting improvement in different areas.

Physical Signs of HGH Treatment

• Less wrinkles on face (75.5%)
• Less sagging skin on face and neck (67%)
• Firmer muscles (60.7%)
• Less body fat (48%)
• Better skin (thicker) (34.5%)
• Thicker head hair (28.1%)>

Disclaimer: Results may vary

Emotional/Mental Improvements of HGH Therapy

• Improved emotional state (71.4%)
• Increased energy (86.8%)
• Improved physical stamina (86.04%)
• Increased ability to stay up late (82.5%)
• Improved resistance to stress ((83.7%)
• Significantly decreased Anxiety (calmer) (73.5%)
• Improved assertiveness (73.1%)
• Improved sense of power (77.8%)
• Improved self-esteem (50%)
• Depression improved or eliminated (82.7%)
• Improved sociability (77.8%)
• Decreased tendency to give sharp verbal retorts (71.0%)

Disclaimer: Results may vary

This study and numerous others demonstrate that treatment with growth hormone results in significant improvements in both physical appearance and in emotional and mental well-being. The enhancement in quality-of-life with the use of growth hormone is truly remarkable.

The FDA has approved hGH for adult deficiency after being the most scrutinized pharmaceutical in history. After many years of research and clinical use, growth hormone has proven to have an excellent long and short-term safety profile with almost no side effects.

Growth Hormone and Weight Loss

In a 1990 study published in the New England Journal of Medicine, the administration of human growth hormone for six months was accompanied by an 8.8 % increase in lean body mass, a 14.4 % decrease in adipose-tissue mass, and a 23.2% improvement in overall body composition. There was a 1.6% increase in average lumbar vertebral bone density, and skin was transformed into a much more youthful appearance with significantly less wrinkles and increased thickness of 7.1 percent.


 Change in body composition

Weight of person


150 pounds

200 pounds

250 pounds

Average increase lean muscle
Average loss of body fat
Overall body composition improvement

13.2 lbs
21.6 lbs
34.8 lbs

17.6 lbs
28.8 lbs
46.4 lbs

22 lbs
36 lbs
58 lbs


Conclusion of the study’s authors:

“Diminished secretion of growth hormone is responsible in part for the decrease of lean body mass, the expansion of adipose-tissue mass (fat), and the thinning of the skin that occur in old age. The effects of six months of human growth hormone on lean body mass and adipose tissue reversed the equivalent of 10-20 years of aging.”

In another study published in New England Journal of Medicine, individuals received 6 months of growth hormone plus gonadal steroids (estrogen and progestin for women and testosterone for men). Body composition was analyzed along with strength, lipid profile, and aerobic capacity. Conclusion:

  • Significant increase in lean muscle mass and a decrease in body fat by 3.5-18%
  • Significant increase in aerobic capacity
  • Improvement in the lipid profile (decrease in total and LDL “bad” cholesterol)
  • Decrease in blood pressure
  • Significant overall additive effect of the sex hormones (estrogen / progesterone / testosterone) and hGH resulting in dramatic improvements in body composition and functioning

“Boomers Believe They’ve Found a Fountain of Youth In a Syringe”

USA Today
November 15, 2000 Issue – Edited Abstract of Article

High-profile Hollywood celebrities boast that using hormone modulation, including human growth hormone (hGH), has them looking better and feeling better. Praising hormone modulation as a way to stay healthy as long as one can, enthusiasm is growing for an anti-aging revolution, with hGH and vitamins as its focus.

HGH is produced by the body in the pituitary gland, and, as we age, the body’s natural hGH levels begin to drop (around the age of 30 or so). Advocates claim that supplementing the waning levels of our own hGH with injections of bioengineered human growth hormone restores the body’s ability to grow muscle tissue, increases bone density, restores energy, enhances memory, and instills a sense of well-being. In other words, it brings one back to the level of age 30 or so.

The specialty of anti-aging medicine began with research about 15 years ago; the Food and Drug Administration approved hGH for “deficient” adults in 1996; and Harvard University proctored the first medical board examinations for anti-aging practitioners in 1997. While there is still some controversy as to whether the symptoms of aging are sufficient to categorize a person as growth hormone deficient, the use of hGH as part of an anti-aging protocol is the edge of a futuristic field of medicine that promises biomedical breakthroughs in many life-preserving areas: regeneration, gene mapping, etc.

Generally, an anti-aging program begins with a comprehensive evaluation of nutritional, metabolic, immune and hormonal functions. The preliminary diagnostics can reveal deficiencies in a number of areas—early signs of osteoporosis, thyroid conditions, blood-sugar imbalances, etc, and regimens are then prescribed to correct these deficiencies. Depending upon the patient’s particular medical needs, the program may include hGH.

Despite internet or advertising scams offering inexpensive sprays or pill forms of hGH, the hormone is potent only when injected. In combination with other anti-aging medical protocols, it has been shown to lower blood pressure, build lean muscle, decrease body fat, improve skin tone, heighten sexual potency, and ensure restful sleep. Some advocates have said that it also thickens hair and sharpens vision, but these are anecdotal accounts. Skeptics point out that the potential side-effects include joint discomfort, carpal tunnel syndrome, fluid retention, and insulin resistance. These problems, however, are generally from larger doses and corrected by simply adjusting the patient’s dosage. Other critics are concerned about “putting things into our body that aren’t naturally there.” Dr. Ronald Klatz, head of the American Academy of Anti-Aging Medicine (A4M), gets exasperated with such nay-sayers. “This is something that we have studied” and “has been in clinical use for the last 50 years. There are tens of thousands, if not hundreds of thousands, of people who have received growth hormone—whether they are children or adults.”

  • Patients, such as Gilman, say, “Every single thing it [hGH] promised, it has delivered with absolutely zero side effects.”
  • Dan Yaffe, 52, a mortgage banker in Las Vegas and hGH user is another believer, even with the high cost. “As long as I’m living, I want to be as healthy and physically fit as possible. What better thing could I put my money into?”

As 20 million baby-boomers turn 50 and another 22 million turn 40, more and more products and programs will be offered through anti-aging practitioners. It is important to remember that hGH is not effective unless it is injected. You need a doctor’s prescription and should be under the supervision of a qualified practitioner to monitor your hormone levels.

Studies of Growth Hormone Deficiency

LARGE AMOUNTS OF PEER REVIEWED RESEARCH, including long-term data, has demonstrated that growth hormone replacement has been shown to improve:

  • energy (1,2)
  • strength (1)
  • cardiac function (3,4,5)
  • blood pressure (6)
  • cholesterol levels (3,6,7,8)
  • insulin sensitivity (6,7,9)
  • cognitive function (10,11)
  • immunity (12,13)
  • psychological well-being (1,2)
  • decrease body fat (1,3,6,7,9,13,15)
  • increase lean muscle (1,6,14,15)
  • prevent and reverse heart disease (1,3,16,17)
  • prevent and improve osteoporosis (3,7,18)
  • increase quality of life (2,3,8)

There is an exponential decline in growth hormone release after age 21 with a 50% decline every 7 years. Almost all individuals over 40 years old have a growth hormone deficit and at age 60 growth hormone production is indistinguishable from those of hypopitutitary patients with organic lesions in the pituitary gland. Life with low growth hormone is shown to be poor in quality and quantity (19).

While many endocrinologists feel the diagnosis of growth hormone deficiency requires the use of growth hormone stimulation testing (dynamic testing), growth hormone and other stimulation tests are shown to be inaccurate, highly variable, non-physiologic, lack adequate sensitivity to detect relative growth hormone deficiencies, do not correlate with the presence of deficiency and do not predict who will respond to therapy (20-32). Requiring stimulation testing to confirm growth hormone deficiency is unnecessary, expensive and carries significant risk to the patient. Thus, they neither are appropriate to perform nor required for the diagnosis of growth hormone deficiency. A clinical diagnosis of growth hormone deficiency, often with support of low or low-normal IGF-1 levels, are the most appropriate means of making the diagnosis of relative growth hormone deficiency.

Hoeck et al evaluated the accuracy of the insulin tolerance test (ITT), which is considered to be the most reliable (and risky) of the dynamic tests. They found that there was no correlation between results of repeated ITT’s, and the results were no better than flipping a coin. The authors conclude:

“The results of this study illustrate the complexity of the regulation of growth hormone secretion and indicate that the ITT is less useful for diagnosing growth hormone deficiency in adults than previously anticipated. The diagnosis of growth hormone deficiency in adults and especially in adult females should not be based on the results of a single ITT alone (24).”

Similarly, Hoeck and Jakobsen, et al evaluated the accuracy and reliability of commonly used stimulation tests. On each subject, 2 ITT, 2 GHRH, 2 clonidine + GHRH were done and then a pyridostigmine + GHRH stimulation tests were done on an extended group of subjects. It was found that there was no correlation in the results of the different tests and the results were not reproducible. The authors conclude:

 “In the individual subject, there was no systematic correlation between the peak growth hormone responses in the different stimulation tests. In conclusion, we found that the stimulated growth hormone responses were highly variable in all tests, and that the peak GH responses differed (25).”

The authors expressed caution in the use and interpretation of stimulation tests in the diagnosis of growth hormone deficiency.
This use of growth hormone stimulation testing in the diagnosis of growth hormone deficiency was reviewed by Rosenfeld et al in the Journal of Endocrinology and Metabolism. The authors state:

“[stimulation testing] is often limited and relies on testing procedures that are, generally, non-physiological, arbitrary, invasive, risky, and subject to considerable interassay variability (20).”

Moorkens et al evaluated the growth hormone secretion in chronic fatigue syndrome patients as compared to normal controls. This study compared physiologic nocturnal secretion, IGF-1 levels and response to various commonly used stimulation tests. This study found that CFS patients have an abnormally low production of growth hormone, as demonstrated by reduced nocturnal secretion of growth hormone and a significantly decreased GH response to ITT (both peak and AUC). The commonly used stimulation tests were shown, however, to have no correlation with ITT testing results (which again has significant risk), and that these stimulation tests were shown to lack the sensitivity to detect significant growth hormone deficiency in these patients (32).

In a prospective randomized placebo controlled study, Rahim et al assessed the accuracy and reliability of commonly used stimulation tests by performing four different stimulation tests on each individual (ITT, glucagon, arginine and clonidine). As with other studies, this study also found that there was no correlation between the responses to different agents in the same individual. Subjects who failed to achieve a growth hormone peak greater than 20mU/l in one test were not the same individuals who responded poorly to other tests. Again, the results of the stimulation tests were no better than flipping a coin. This study also demonstrated the risk and side-effects of performing such testing; all patients suffered from significant hypotension; over half of the patients could not carry out normal daily activities for the rest of the day after the tests; venous thrombosis occurred in over a third of patients and over 10% had significant nausea and vomiting (26). There have also been reported deaths and neurological damage associated with growth hormone stimulation testing (33).

Cacciari et al investigated the sensitivity of utilizing growth hormone stimulation tests in 98 children with clear evidence of impaired growth hormone production compared to 274 healthy controls. They found that growth hormone deficiency correlated with IGF-1 levels, but that standard arbitrary cutoffs of what is considered to be a normal IGF-1 level and the use of growth hormone stimulation tests with standard cutoffs lacked sufficient sensitivity. The majority of patients with clear evidence for growth hormone deficiency would have been inappropriately labeled as normal and children who would likely have benefited from treatment would have been left untreated. The authors conclude:

“Our data adds weight to the opinion that present criteria for defining growth hormone deficit may be too restrictive. Consequent implications regarding therapy are evident (27).”

Wilson et al reviewed the use of growth hormone stimulation tests in determining a person’s growth hormone secretory status in a 2005 edition of Growth Hormone & IGF Research. They state:

“Historically, growth hormone stimulation testing has played a prominent role in diagnosing growth hormone deficiency. There are growing concerns, however, that growth hormone stimulation testing, particularly as currently conducted in the USA, is neither precise nor accurate in quantifying a patient’s growth hormone secretory status (28).”

Tassoni et al tested the variability of growth hormone stimulation tests in the Journal of Endocrinology and Metabolism. They performed several commonly used stimulation tests in duplicate as well as 12-hour overnight physiologic growth hormone secretion testing. They found that there was little or no correlation between repeated testing in the same individuals (coefficient of variance being 89% in one group and 66% in another) as well as little correlation with physiologic night-time growth hormone secretion. When the same stimulation test was repeated on the same individual, over half had disparate results (showing deficient on one test and normal on the other). Again, the results were almost no better than flipping a coin. They state that growth hormone stimulation tests cannot be used with any confidence to diagnose or rule-out growth hormone deficiency and recommend that repeated 12-hour overnight physiologic growth hormone secretion testing be utilized. This requires, however, that multiple venous samples be obtained throughout the night via an indwelling catheter, which is not practical outside of a research setting. The authors state:

“In conclusion, the usual approach for evaluating growth hormone secretion does not take into account the variability of the response to the various tests. This may be misleading, especially for patients that have hormone secretion at the lower limit of normalcy (30).”

Gandrud et al reviewed the use of growth hormone stimulation testing in the 2004 Growth Hormone & IGF Research. This extensive review clearly demonstrates that growth hormone stimulation tests lack precision and accuracy, are not concordant with the proper diagnosis of growth hormone deficiency and do not predict response to therapy. They recommend that the diagnosis of growth hormone deficiency should be based on clinical parameters as well as IGF-1 and state:

“…the insulin tolerance test using the current cutoff for failure should not be considered the gold standard for the diagnosis of growth hormone deficiency…We examined the pitfalls associated with growth hormone stimulation tests, specifically, the lack of reliability and accuracy of these tests, and their inability to predict who will benefit from growth hormone therapy. We recommend that growth hormone stimulation tests no longer routinely be used for the diagnosis of growth hormone deficiency…(31).”

Conclusion: Aging adults are shown to have a relative deficiency of growth hormone and supplementation with growth hormone can be of significant benefit. A clinical diagnosis of growth hormone deficiency, often with support of low-normal IGF-1 levels, are the most appropriate means of making the diagnosis of growth hormone deficiency. Growth hormone stimulation tests are shown to be inaccurate, unreliable, highly variable, risky, non-physiologic and lack adequate sensitivity to detect relative growth hormone deficiencies. Thus, the growth hormone stimulation tests generally do not add significant useful information in the clinical management of these patients and are not recommended.


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