GROWTH-HORMONE SECRETAGOGUES IN PATHOLOGICAL STATES - DIAGNOSTIC IMPLICATIONS

The identification and cloning of the receptor for synthetic growth ho rmone (GH) secretagogues, even before the endogenous ligand has been i dentified or its precise physiological role established, suggests that there in a novel target of action for this class of drug. In an attem pt to select patients who will benefit from GH treatment, GH secretago gues are being evaluated for their usefulness in diagnosing GH deficie ncy. The effects of GH-releasing peptides (GHRPs) on GH release as a f unction of age and metabolic status, and in different neuroendocrine p athologies, are described, as are the different mechanisms of action, potency and reproducibility of the response to GHRPs compared with GH- releasing hormone (GHRH). GHRPs offer the advantage over GHRH in natur al models of deranged GH secretion in that, in Various metabolic state s (e.g., obesity, anorexia nervosa and non-insulin-dependent diabetes mellitus), the GH response to GHRH is more impaired than it is to GHRP s. However, in some neuroendocrine pathologies, the reverse is true. T hus, both secretagogues provide separate information on the physiologi cal status of somatotrophs.