GHRH is a hypothalamic hormone that stimulates growth hormone secretion from the anterior pituitary gland. Since the discovery of ectopic GHRH syndrome, an appreciable number of patients who suffer from acromegaly caused by GHRH production have been reported; neoplasms associated with ectopic GHRH syndrome are thus far limited to bronchial carcinoid and pancreatic endocrine tumour, although ectopic GHRH production is frequent in a variety of neoplasms with neuroendocrine characteristics, including small-cell lung carcinoma. It appears that this is not a frequent cause of acromegaly (much less than one per cent), but this entity is very important for the differential diagnosis of multiple endocrine neoplasia (MEN) type I.
