Growth Hormone Replacement in Older Men
- Author: Angela Gentili, MD; Chief Editor: George T Griffing, MD more...
Background
Discussion in this article is limited to hyposomatotropism of aging. For more information on adult growth hormone deficiency (GHD), see Hypopituitarism (Panhypopituitarism).
The decrease in lean body mass and increase in adipose tissue that occurs with aging have been suggested to be partly due to the age-associated decrease in growth hormone (GH) secretion and insulin-like growth factor-1 (IGF-1), also known as somatomedin C, which is produced by the liver and other tissues in response to GH. This decline in the secretory activity of the GH–IGF-1 axis has been termed somatopause or hyposomatotropism of aging. Whether this decrease in GH secretion should be treated is debatable.[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Pathophysiology
GH secretion
GH is released from the anterior pituitary gland in a pulsatile manner. Two hypothalamic hormones control GH secretion: Growth hormone-releasing hormone (GHRH) stimulates GH secretion, and somatostatin inhibits it. The majority of GH secretion occurs at night during slow-wave sleep, when somatostatin release is diminished.
GH stimulates production of IGF-1 in the liver and other tissues. IGF-1 circulates through the bloodstream bound to 6 specific binding proteins in several combinations. The major serum IGF-binding protein is insulinlike growth factor binding protein-3 (IGFBP-3). Both GH and IGF-1 have important metabolic actions in several tissues.
A single measurement of plasma GH levels is difficult to interpret because of the pulsatile secretion of GH. Levels of IGF-1 vary little during the day; therefore, assays of IGF-1 have been used as a better screening indicator of the status of the GH-IGF-1 axis.
Effect of age on GH secretion
Several studies have shown that the amplitude of GH pulses is reduced with aging both in men and women.[11] In aging men, GH secretion declines by 50% every 7 years after age 18-25 years. The negative effect of age on 24-hour mean serum GH is twice as much in men as in premenopausal women. Estrogens may have a protective effect that limits the rate of decline of GH secretion with aging.
IGF-1 and IGFBP-3 levels also decrease with aging. This decline of the GH–IGF-1 axis is probably caused by altered hypothalamic regulation (ie, decrease in GHRH and increase in somatostatin), rather than a decreased capacity to secrete GH.
The pathophysiology of the somatopause is confounded by several variables that can contribute to the decline in GH secretion associated with aging. These variables include the following:
- Adiposity: Individuals who are moderately to markedly obese have profound suppression of GH secretion at any age.
- Decreased production of sex steroid hormones: Falling levels of testosterone in men and estrogens in women affect GH secretion.
- Decreased physical fitness: A strong correlation exists between aerobic capacity and 24-hour serum GH concentration.
- Fragmented sleep: GH secretion can be affected by altered sleep patterns because it occurs predominantly during slow-wave sleep.
- Malnutrition: Poor nutritional status negatively affects IGF-1 synthesis and action.
Epidemiology
Frequency
United States
Incidence is unknown because somatopause may be part of normal aging rather than a disease.
Age
In aging men, GH secretion declines by 50% every 7 years after age 18-25 years.
Waters DL, Baumgartner RN, Garry PJ, Vellas B. Advantages of dietary, exercise-related, and therapeutic interventions to prevent and treat sarcopenia in adult patients: an update. Clin Interv Aging. 2010;5:259-70. [Medline].
Harman SM, Blackman MR. The Effects of Growth Hormone and Sex Steroid on Lean Body Mass, Fat Mass, Muscle Strength, Cardiovascular Endurance and Adverse Events in Healthy Elderly Women and Men. Horm Res. 2003;60:121-124. [Medline].
Harman SM, Blackman MR. Use of growth hormone for prevention or treatment of effects of aging. J Gerontol A Biol Sci Med Sci. 2004;59:652-8. [Medline].
Kiel DP, Puhl J, Rosen CJ, Berg K, Murphy JB, MacLean DB. Lack of an association between insulin-like growth factor-I and body composition, muscle strength, physical performance or self-reported mobility among older persons with functional limitations. J Am Geriatr Soc. Jul 1998;46(7):822-8. [Medline].
Sherlock M, Toogood AA. Aging and the growth hormone/insulin like growth factor-I axis. Pituitary. 2007;10(2):189-203. [Medline].
[Best Evidence] Liu H, Bravata DM, Olkin I, Nayak S, Roberts B, Garber AM. Systematic review: the safety and efficacy of growth hormone in the healthy elderly. Ann Intern Med. Jan 16 2007;146(2):104-15. [Medline].
Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Shalet SM, Vance ML. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. May 2006;91(5):1621-34. [Medline].
Lin L, Saha PK, Ma X, Henshaw IO, Shao L, Chang BH, et al. Ablation of ghrelin receptor reduces adiposity and improves insulin sensitivity during aging by regulating fat metabolism in white and brown adipose tissues. Aging Cell. Sep 5 2011;[Medline].
Holzenberger M. Igf-I signaling and effects on longevity. Nestle Nutr Workshop Ser Pediatr Program. 2011;68:237-49. [Medline].
Borst SE. Interventions for sarcopenia and muscle weakness in older people. Age Ageing. 2004;33:548-555. [Medline].
Veldhuis JD, Iranmanesh A, Weltman A. Elements in the pathophysiology of diminished growth hormone (GH) secretion in aging humans. Endocrine. Aug 1997;7(1):41-8. [Medline].
[Guideline] Ho KK. Consensus guidelines for the diagnosis and treatment of adults with GH deficiency II: a statement of the GH Research Society in association with the European Society for Pediatric Endocrinology, Lawson Wilkins Society, European Society of Endocrinology, Japan Endocrine Society, and Endocrine Society of Australia. Eur J Endocrinol. Dec 2007;157(6):695-700. [Medline].
Rudman D, Feller AG, Nagraj HS, Gergans GA, Lalitha PY, Goldberg AF, et al. Effects of human growth hormone in men over 60 years old. N Engl J Med. Jul 5 1990;323(1):1-6. [Medline].
Kokshoorn NE, Biermasz NR, Roelfsema F, Smit JW, Pereira AM, Romijn JA. GH replacement therapy in elderly GH-deficient patients: a systematic review. Eur J Endocrinol. May 2011;164(5):657-65. [Medline].
Urban RJ. Growth hormone and testosterone: anabolic effects on muscle. Horm Res Paediatr. 2011;76 Suppl 1:81-3. [Medline].
Brill KT, Weltman AL, Gentili A, Patrie JT, Fryburg DA, Hanks JB, et al. Single and combined effects of growth hormone and testosterone administration on measures of body composition, physical performance, mood, sexual function, bone turnover, and muscle gene expression in healthy older men. J Clin Endocrinol Metab. Dec 2002;87(12):5649-57. [Medline].
Elgzyri T, Castenfors J, Hagg E, Backman C, Thoren M, Bramnert M. The effects of GH replacement therapy on cardiac morphology and function, exercise capacity and serum lipids in elderly patients with GH deficiency. Clin Endocrinol (Oxf). Jul 2004;61(1):113-22. [Medline].
Haydar ZR, Blackman MR, Tobin JD, Wright JG, Fleg JL. The relationship between aerobic exercise capacity and circulating IGF-1 levels in healthy men and women. J Am Geriatr Soc. Feb 2000;48(2):139-45. [Medline].
Bach MA, Rockwood K, Zetterberg C, Thamsborg G, Hebert R, Devogelaer JP, et al. The effects of MK-0677, an oral growth hormone secretagogue, in patients with hip fracture. J Am Geriatr Soc. Apr 2004;52(4):516-23. [Medline].
Papadakis MA, Grady D, Black D, Tierney MJ, Gooding GA, Schambelan M, et al. Growth hormone replacement in healthy older men improves body composition but not functional ability. Ann Intern Med. Apr 15 1996;124(8):708-16. [Medline].
Kaiser FE, Silver AJ, Morley JE. The effect of recombinant human growth hormone on malnourished older individuals. J Am Geriatr Soc. Mar 1991;39(3):235-40. [Medline].
Blackman MR, Sorkin JD, Münzer T, Bellantoni MF, Busby-Whitehead J, Stevens TE, et al. Growth hormone and sex steroid administration in healthy aged women and men: a randomized controlled trial. JAMA. Nov 13 2002;288(18):2282-92. [Medline].
Genentech Inc. Nutropin (R) [somatropin (rDNA origin) for injection] prescribing information. Available at: http://www.genentech.com/gene/index.jsp. [Full Text].
Vitiello MV, Moe KE, Merriam GR, Mazzoni G, Buchner DH, Schwartz RS. Growth hormone releasing hormone improves the cognition of healthy older adults. Neurobiol Aging. Feb 2006;27(2):318-23. [Medline].

