Sustained improvement in growth velocity and recovery from suboptimal growth hormone (GH) secretion after treatment with human pituitary GH-releasing hormone-(1-44)-NH2.

The sustained effect of human pancreatic GH-releasing hormone [hpGHRH-(1-44)-NH2] on growth rate and GH secretory patterns was studied in 14 patients (10 males and 4 females; aged 10-16 yr; all Tanner stage I or II). Nine children had inadequate spontaneous GH secretion (ISGHS), while 5 had classic GH deficiency. Seven of 9 patients with ISGHS and 1 of 5 patients with GH deficiency were given 2 sc injections/day of 5 micrograms/kg GHRH for 2-3 months; the others received 5 pulses of GHRH (5 micrograms/kg BW.pulse) for 6 nights a week for 2-13 months, given every 3 h. Six of the nine ISGHS patients increased their growth velocity in response to GHRH therapy. These same six patients maintained an increased growth velocity for up to 24 months after GHRH was discontinued. The remaining three ISGHS patients did not show a significant growth response to GHRH administration. Neither a temporary nor a sustained growth response was correlated with spontaneous overnight GH secretion in these patients. In contrast, three of five classical GH deficiency patients exhibited increased growth velocity while undergoing GHRH therapy, but growth returned to preintervention rates upon discontinuation of treatment. The other two of the five classic GH deficiency patients failed to demonstrate any growth response to GHRH treatment. The increased growth velocity that was sustained for long intervals even after discontinuation of GHRH in ISGHS patients may indicate restoration of normal regulation of the hypothalamic-pituitary GH secretion axis.