Cranial irradiation for cerebral and nasopharyngeal tumours in children: evidence for the production of a hypothalamic defect in growth hormone release

Abstract

A synthetic 29-amino acid analogue of human pancreatic GH-releasing hormone (GHRH(1–29)NH₂) has recently been shown to stimulate the release of GH in normal subjects. We have studied the GH response to GHRH(1–29)NH₂ in nine children irradiated for brain and nasopharyngeal tumours, who were not growing and were deficient in GH as assessed by insulin-induced hypoglycaemia. Serum GH rose in response to GHRH(1–29)NH₂ in all the children, and in five the peak serum GH response was > 20 mu./l. The data suggest that when hypothalamo-pituitary irradiation results in GH deficiency, this is due to a failure of the synthesis or delivery of endogenous GH RH from the hypothalamus to the pituitary cells. It also suggests that it may be possible to treat such children using synthetic GHRH in place of exogenous GH. J. Endocr. (1986) 108, 25–29