Growth hormone and ageing

The impact of frailty in the elderly on the outcome of surgery in the aged

As the population continues to age, we will continue to encounter issues involving aging and the elderly. Despite these issues, knowledge is expanding and evolving with new solutions to ongoing problems. Mechanistically, frailty at its root is a symptom of growing old, with cascades and circuitous feedback between organ systems at all levels. Clinically, frailty is as equally dynamic and its multifactorial nature represents a unique challenge to the surgical community and warrants the integration of geriatric assessment into clinical practice. Integration within clinical practice includes using an interdisciplinary approach, where surgeons work with anesthesiologists, geriatricians, nursing, rehabilitation, nutritionists, and other support staff to provide holistic assessment, efficient delivery, and higher quality of care. This in hand, recognition of frailty can occur in a timely fashion to initiate treatment, decreasing the risk of morbidity and mortality for improved surgical outcomes.

A review of the effects of growth hormone changes on symptoms of frailty in the elderly with chronic kidney disease

The incidence and prevalence of chronic kidney disease (CKD) is increasing worldwide, especially in the elderly. Recently, functional impairment and frailty have been recognized as factors affecting the quality of life, and outcomes in elderly patients with CKD and therapeutic interventions to improve function and reduce frailty are therefore being considered. Growth hormone (GH) levels decrease with age and GH actions are impaired in CKD patients. GH stimulates protein synthesis, bone, and glucose metabolism, and affects body composition by reducing body fat and increasing lean body mass. An increase in lean body mass may reduce frailty and thus avoid functional impairment. Thus, providing GH to elderly CKD patients could potentially improve outcomes and quality of life by lowering the risk of frailty and associated functional impairment. There are few studies assessing the long-term effects of GH administration on symptoms of frailty in elderly patients with CKD. In this review we will try to shed some light on the trials assessing the administration of GH to elderly subjects and to patients with CKD and focus on the possible role GH administration may play to improve frailty and quality of life in those patients.

Frailty

Frailty is a common condition in older people. It now can be objectively defined by the Fried criteria. When recognized, early intervention should begin with the institution of endurance, resistance, and balance exercises. In men with testosterone deficiency a trial of testosterone replacement should be considered. Vitamin D deficiency needs to be recognized and treated. Appropriate treatment of underlying diseases, such as anemia, diabetes mellitus, and congestive heart failure, are a key management principle. In people who have frailty aggressive health promotion and disease prevention techniques can lead to an inhibition of the downward spiral to disability.

Justified and unjustified use of growth hormone

Growth hormone (GH) replacement therapy for children and adults with proven GH deficiency due to a pituitary disorder has become an accepted therapy with proven efficacy. GH is increasingly suggested, however, as a potential treatment for frailty, osteoporosis, morbid obesity, cardiac failure, and various catabolic conditions. However, the available placebo controlled studies have not reported many significant beneficial effects, and it might even be dangerous to use excessive GH dosages in conditions in which the body has just decided to decrease GH actions. GH can indeed induce changes in body composition that are considered to be advantageous to GH deficient and non-GH deficient subjects. In contrast to GH replacement therapy in GH deficient subjects, however, excessive GH action due to GH misuse seems to be ineffective in improving muscle power. Moreover, there are no available study data to indicate that the use of GH for non-GH deficient subjects should be advocated, especially as animal data suggest that lower GH levels are positively correlated with longevity.

Frailty in the elderly: contributions of sarcopenia and visceral protein depletion

In any given population of free-living individuals 65 years of age and older, a substantial proportion (in the range of 6% to 25%) suffers from many of the elements of the syndrome of frailty. Although the syndrome is complex and still lacks a standard definition, there is a growing consensus about the signs and symptoms as well as the pattern of biological correlates that characterize this disorder. Patients who are afflicted with frailty typically exhibit loss of muscle strength, fatigue easily, are physically inactive, and have a slow-and often unsteady-gait, with an increased risk (and fear) of falling. They are likely to have a poor appetite and to have undergone a recent, unintentional loss of weight. Frail individuals are more likely than the nonfrail to experience impaired cognition and depression. They die sooner. Frailty, of course, is frequently complicated by a variety of coexistent illnesses. Among the biological correlates of frailty are sarcopenia (now readily measurable by dual-energy x-ray absorptiometry [DXA]), osteopenia (with an increased susceptibility to fracture), and activation of the inflammatory and coagulation systems, with a rise in inflammatory cytokines and several markers of coagulopathy. Age-dependent changes in a number of hormones also appear to promote the development of frailty in the elderly, particularly via their effects on muscle mass and strength, bone density, and by contributing to activation of the catabolic cytokines. In particular, serum levels of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) decline progressively during aging, and an association between reduction in the levels of these hormones and the involution of advancing age has been proposed. It is not yet known whether, in comparison with their nonfrail counterparts, frail individuals consistently manifest larger reductions in GH and IGF-1 (and other anabolic hormones). More research is needed before it will be known whether the benefits of administering GH to the frail elderly will outweigh the disadvantages. The poor appetite and weight loss that occur in many frail individuals are likely to be accompanied by a degree of visceral protein depletion (with its attendant morbidity), which can be estimated by making serial measurements of indicators of visceral protein status such as transthyretin (TTR), retinol-binding protein (RBP), and albumin. One characteristic of the frailty syndrome that distinguishes it from the effects of aging per se is the potential reversibility of many of its features. Progressive resistance training is feasible for many elderly individuals-even the oldest old-and, by increasing muscle mass and strength, can ameliorate or reverse important aspects of physical frailty. To the extent that visceral protein depletion has been caused by an inadequate intake of calories and protein, consumption of a more adequate diet can result in betterment of the frail patient's nutritional status, as determined by clinical improvement and favorable changes in TTR, RBP, and albumin.

Growth hormone (GH) and GH-releasing peptide-6 increase brain insulin-like growth factor-I expression and activate intracellular signaling pathways involved in neuroprotection

Beneficial effects of GH on memory, mental alertness, and motivation have been documented. Many actions of GH are mediated through IGF-I; hence, we investigated whether systemic administration of GH or GH-releasing peptide (GHRP)-6 modulates the brain IGF system. Treatment of adult male rats with GHRP-6 or GH for 1 wk significantly increased IGF-I mRNA levels in the hypothalamus, cerebellum, and hippocampus, with no effect in cerebral cortex. Expression of the IGF receptor and IGF-binding protein (IGFBP)-2 were not affected. Phosphorylation of Akt and Bad was stimulated in areas where IGF-I was increased, with no change in MAPK or glycogen synthase kinase-3beta. This suggests that GH and GHRP-6 activate phosphatidylinositol kinase intracellular pathways involved in cell survival in response to growth factors. Indeed, the antiapoptotic protein Bcl-2 was augmented in these same areas, with no change in the proapoptotic protein Bax. IGFBP-5, also reported to be involved in neuron survival processes, was increased mainly in the hypothalamus, suggesting a possible neuroendocrine role. In conclusion, GH and GHRP-6 modulate IGF-I expression in the central nervous system in an anatomically specific manner. This is coincident with activation of intracellular signaling pathways used by IGF-I and increased expression of proteins involved in cell survival or neuroprotection.

Visceral obesity and the role of the somatotropic axis in the development of metabolic complications

It is well recognized that aberrant fat localization such as visceral obesity rather than total body fat mass is a major risk factor for cardiovascular disease and type 2 diabetes mellitus. During recent decades, several studies have described a range of metabolic disturbances associated with abdominal obesity, including glucose intolerance, hyperinsulinaemia, insulin resistance, hypertension and dyslipoproteinaemia, now widely known as the metabolic syndrome. Several abnormalities in the hypothalamic-pituitary axis have been described associated with visceral obesity, suggesting a central neuroendocrine dysregulation including increased cortisol concentration and impaired gonadotropin and growth hormone (GH) secretion. Some steps in the chain of events in this theory still remain unclear, however, although these findings have introduced new therapeutic possibilities. These include therapy with sex steroids in both viscerally obese men and women, and several attempts to use GH to treat the endocrine abnormalities present in visceral obesity. The results of these studies are promising, but the therapies are still not recommended for general use.