Current Concepts of Estrogen-Regulated Growth Hormone Secretion in Postmenopausal Women
Johannes D Veldhuis
General Clinical Research Center, Mayo School of Graduate Medical Education,
Mayo Clinic, Rochester, MN, USA
Epidemiological investigations correlate organic growth hormone (GH) deficiency (hyposomatotropism) with decreased insulin sensitivity, dyslipidemia, increased cardiovascular mortality, intra-abdominal adiposity, sarcopenia, osteopenia, diminished quality of life, and possibly reduced cognitive
function [1,2]. Aging increases the prevalence of these signs and symptoms and is associated with an exponential decline in systemic GH and insulin-like growth factor-I (IGF-I) concentrations, beginning at the transition between late puberty and early adulthood [3–5]. However, maximally stimulated GH secretion, GH elimination kinetics, and the capability of GH to drive hepatic IGF-I production are preserved in the older individual [6–9]. Thus, aging appears to impair the normal regulation of GH secretion, rather than irreversibly reducing the capacity to secrete GH or blocking the actions of GH on the liver.