Sex-steroid control of the aging somatotropic axis

Growth hormone (GH) concentrations decline progressively with increasing age. In contrast, the maximal pituitary secretory capacity, plasma elimination kinetics, and hepatic actions of GH are preserved in older people. Reduced availability of GH and thereby insulin-like growth factor in the elderly has significant implications. In particular, epidemiologic investigations correlate hyposomatotropism with reduced insulin sensitivity, dyslipidemia, increased cardiovascular mortality intra-abdominal adiposity, sarcopenia, osteopenia, and diminished quality of life. Obesity forecasts decreased GH secretion in the adult. In addition, sex steroid depletion after adolescence predicts relative GH deficiency. Conversely, supplementation with estradiol or an aromatizable androgen, such as testosterone, stimulates GH production in aging and hypogonadal adults. Recent developments in this arena allow new clinical perspectives in aging, which are highlighted in this article.