EFFECT OF CHRONIC TREATMENT WITH BIOSYNTHETIC GROWTH-HORMONE (GH) ON THE GH RESPONSE TO DOUBLE GH-RELEASING HORMONE ADMINISTRATION IN CHILDREN WITH SHORT STATURE

Growth hormone (GH) exerts (GH) negative feedback on its own secretion through direct and indirect mechanisms. Normal children, unlike adult s, display consecutive GH responses after repeated GH-releasing hormon e (GHRH) administration. In this study, we investigated the effects of long-term GH administration on this peculiar secretory pattern. Eight children with severe short stature and impaired GH responses to supra pituitary provocative stimuli associated with normal GH responsiveness to GHRH, underwent, while on chronic treatment with biosynthetic GH a nd on the 10th day following drug withdrawal, a double bolus GHRH test (two GHRH injections of 1 mu g/kg b.w. given as i.v. boluses two hour s apart). During GH therapy the GH response to the first GHRH bolus ap peared to be reduced, though not significantly so, compared to that ob served at diagnosis; after treatment withdrawal, this response returne d quite similar to pretreatment. Both during and after treatment, the GH response to the second GHRH bolus was comparable for magnitude to t hat evoked by the first application. In conclusion, even prolonged tre atments with rhGH do not induce persisting alterations of the physiolo gical mechanisms subserving GH regulation. (C) 1997, Editrice Kurtis.