THE GROWTH-HORMONE RESPONSE TO HEXARELIN IN PATIENTS WITH PRADER-WILLI-SYNDROME

Hexarelin (Hex) is a synthetic hexapeptide with potent GH-releasing ac tivity in both animals and men. Aim of this study was to evaluate the GH response to a maximal dose of Hex and GH-releasing hormone (GHRH) i n a group of patients with Prader-Willi syndrome (PWS). Seven patients (4 boys and 3 girls, age 2.4-14.2 yr) with PWS, 10 prepubertal obese children (7 boys and 3 girls, age 7.5-12.0 yr), and 24 prepubertal sho rt normal children (11 boys and 13 girls, age 5.9-13 yr) with body wei ght within +/-10% of their deal weight were studied. All subjects were tested on two occasions with GHRH 1-29 at the dose of 1 mu g/Kg iv, a nd with Hex at the dose of 2 mu g/Kg iv. In the PWS patients the GH re sponse to GHRH (peak=6.4+/-2.0 mu g/l, p<0.0001;AUC=248+/-70 mu g min/ l, p<0.0001) was significantly lower than that observed In the short n ormal children and similar to that observed in the obese children. In the PWS children the GH response to Hex (peak =7.5+/-1.6 mu g/l; AUC=3 09+/-53) was similar to that observed after GHRH and significantly low er than that observed in the obese children (p<0.05). The results of t his study show that PWS patients have a blunted GH response to the adm inistration of a maximal dose of Hex. Whether these findings reflect a more severe pituitary GH deficiency in PWS than in obese children or a deranged hypothalamic regulation of GH secretion need further invest igation. (J. Endocrinol. Invest. 21:501-505, 1998) (C) 1998, Editrice Kurtis.