Differences of hexarelin-induced prolactin and cortisol responses between prepubertal and early pubertal short children and lack of correlation with gonadotropin-releasing hormone-induced gonadotropin response

Hexarelin (HEX), a synthetic hexapeptide with strong GH-stimulating activit y, is known to induce the release of prolactin (PRL) and cortisol (F). The responses of GH and F vary according to age and pubertal development, corre lating with serum levels of sex steroids, while the release of PRL does not . We evaluated GH, PRL and F responses to HEX (2 mu g/kg i.v.) in 19 childr en with short stature, 12 prepubertal (Tanner stage I) and 7 early pubertal (stage II), and their correlation with those of FSH and LH to GnRH and wit h the serum levels of testosterone (T) or estradiol (E-2). At baseline, the GH, PRL, F and sex steroid serum levels did not vary in the two groups of patients. HEX induced a strong GH and a slight PRL increase in prepubertal and early pubertal children, with no differences in the extent of the respo nse, while F secretion was not affected in either group; these responses di d not correlate with those of the gonadotropins to GnRH nor with basal T or E-2.