Conflicts with the somatopause.

Abstract

Secretion of growth hormone (GH) falls with increasing age, and early studies of GH secretion in elderly patients suggested that secretion may cease in a proportion of adults aged over 60 years. In order to determine whether organic disease of the hypothalamic-pituitary axis in adults aged over 60 years results in GH deficiency distinct from the age-related decline in GH secretion, studies were performed in subjects aged 61-88 years. GH secretion in patients with GH deficiency was reduced by 90% compared with controls. Serum insulin-like growth factor-I levels in patients with organic GH deficiency were significantly reduced compared with normal data, but only 17% had concentrations below the lower limit of the normal range. Although levels of IGF binding protein-3 in patients were lower when compared with normal data, all were within the normal range. There was a significant increase in fat mass in patients with GH deficiency compared with healthy controls. Unlike younger adults with GH deficiency, no significant reduction in lean mass was demonstrated in adults with GH deficiency aged over 60 years. Serum osteocalcin and deoxypyridinoline excretion were significantly reduced in patients with GH deficiency, suggesting a reduction in bone turnover. Despite this, total body bone mineral content and bone mineral density in the hip and spine were not reduced compared with controls. In conclusion, organic disease of the hypothalamic-pituitary axis in adults aged over 60 years results in GH deficiency distinct from the age-related decline in GH secretion.