Growth hormone-releasing hormone: studies in normal subjects and patients with disorders of growth hormone secretion.

Growth hormone-releasing hormone (GHRH) has been characterised as a 40-44 residue peptide with full biological activity residing in the first 29 residues. In normal subjects GHRH selectively promotes the release of growth hormone (GH) with little change in responsiveness throughout childhood and young adult life. The majority of 'GH-deficient patients' show a GH response to GHRH, suggesting that they have a hypothalamic defect in GH release. GHRH given subcutaneously promotes growth in 50% of GH-deficient children, and it is likely that depot-preparations of GHRH will provide a practical alternative treatment for GH deficiency. GHRH has provided an important method to evaluate pituitary GH reserve and has greatly improved our understanding of both normal and abnormal GH secretion.