Role of ghrelin in growth hormone-deficient patients

Abstract

Ghrelin is the endogenous ligand for the growth hormone (GH) secretagog receptor and exogenous ghrelin is a strong stimulator of GH secretion. Whether endogenous ghrelin is a major regulator of GH release remains dubious, but there is increasing evidence to suggest that ghrelin exhibits direct effects on appetite regulation. Systemic ghrelin levels in patients with GH deficiency (GHD) are normal, whereas GH substitution moderately suppresses ghrelin. Certain subgroups of GHD do respond to ghrelin with significant GH release, but the clinical implications are uncertain. Administration of ghrelin or a synthetic GH secretagog in other conditions with low GH levels, such as obesity and aging, has also been performed in controlled trials and has been shown to translate into insulin-like growth factor-I stimulation and changes in body composition; however, long-term data are not available. Even though ghrelin does not seem to be abnormal in patients with classic GHD, these patients constitute an interesting model for studying GH- and adrenocorticotropic hormone-independent effects of ghrelin.

Keywords::

• ghrelin
• growth hormone
• growth hormone deficiency
• growth hormone secretagog