ENDOGENOUS NOCTURNAL GROWTH HORMONE (GH) RELEASE CONTINUES TO OCCUR IN PUBERTAL CHILDREN WITH IDIOPATHIC SHORT STATURE (ISS) DESPITE GH THERAPY

Abstract

We have shown that the GH axis is resilient with a return of pulsatile CH release 48 hours after injection of GH in children with ISS (JCEM 70:1612, 1990). Pharmacokinetics of GH after a subcutaneous (SC) dose of GH has been performed in children with idiopathic GH deficiency (JCEM 72:1148, 1991). This study was performed to determine if daily GH therapy influences the endogenous nocturnal pulsatile GH release in prepubertal (PP) and pubertal (P) males. GH levels were obtained every 20 minutes over a 24 hour period from 9a.m.-9a.m. in 7 healthy children with ISS (height < 5%ile; and GH levels > 10ng/ml in response to provocative stimuli) on GH treatment for at least 3 months. GH (Protropin) 0.043mg/kg SC was given at 7 p.m. on the day of study. 5 pubertal males (Testes > 6 ml) and 2 prepubertal males with a Body mass index SD score < 2 SD of age- derived normal measures have been studied. GH parameters examined included 24 hour mean GH levels, mean peak frequency, and maximum GH peak amplitude (max GH-PA). GH peak analysis was performed using the Cluster Analysis Program.Pubertal boys achieved a higher 24 hour mean GH and a higher mean max GH-PA than the 2 prepubertal boys studied. Furthermore, the mean max GH-PA was higher than the levels of 14.16 ± 7.72 occurring in GH deficient boys reported previously (JCEM 72:1148, 1991). The presence of robust endogenous GH peaks in pubertal children with ISS indicates that endogenous GH release occurs despite regularly occurring evening injections of GH. GH therapy criteria in puberty may require revision.