Growth Hormone (GH) Status and Body Composition in Normal Ageing and in Elderly Adults with GH Deficiency

Abstract

Similarities have been observed between the changes associated with ageing and the symptoms of growth hormone (GH) deficiency. Changes such as increased fat mass and decreased muscle mass occur both in GH-deficient patients and in otherwise healthy elderly individuals. Moreover, ageing is associated with decreasing GH and insulin-like growth factor I (IGF-I) levels. It has been suggested, therefore, that hypothalamic-pituitary disease leading to GH deficiency (GHD) in elderly patients would have less impact than in younger adults. Studies suggest that healthy elderly individuals have normal pituitary reserves of GH, but that spontaneous GH secretion falls by around 14% per decade of adult life, leading to a state of functional GH insufficiency. Despite this, elderly patients with GHD experience reductions in GH secretion and IGF-I levels, compared with controls, which are of similar magnitude to those seen in younger GH-deficient adults. The metabolic changes associated with GHD are also seen in elderly patients compared with healthy elderly controls. Fat mass, particularly in the abdominal region, is significantly increased, with a strong correlation between fat mass and body mass index. Markers of bone formation and resorption are significantly reduced in the GH-deficient patients. Elderly adults who have hypothalamic-pituitary disease have a degree of GHD that can be distinguished from the decline in GH and IGF-I levels that is seen with normal ageing. GHD in elderly patients leads to significant changes in body composition and bone. Thus, these patients are likely to benefit from GH replacement therapy.