28 GROWTH HORMONE (GH) SECRETORY PATTERNS IN CHILDREN WITH SHORT STATURE

Abstract

Thirty-six healthy children, 2½ - 16½ years old, (26 males, 10 females) with short stature, subnormal rate of growth and stimulated GH levels > 7 ng/ml, had measurements of CH every ½ hr for 24 hr. Based on the 24 hr GH concentration, the patients (pts) were separated into 2 groups of 18. The 24 hr GH concentration was normal (> 3.0 ng/ml; B.E. Spilliotis et al, JAMA 1984) in all pts in gr I and abnormal in all gr II pts. The mean (± SEM) 24 hr GH concentration, the number of GH pulses/24 hr and the mean peak GH amplitude were significantly greater (p < 0.05 to p < 0.0005) in gr I (4.08 ± 0.23; 4.6 ± 0.3 and 7.2 ± 0.35) than the corresponding values in gr II (2.31 ± 0.09; 2.27 ± 0.34 and 4.4 ± 0.33). The mean highest stimulated CH level in gr I was 20.1 ± 1.7 ng/ml (range 12.5 - 39.5 ng/ml) and significantly greater (p < 0.01) than the level of 14.5 ± 1.13 ng/ml (range 9.5 - 25.5 ng/ml) in gr II. In pts in gr I the mean 24 hr GH concentration and the number of GH pulses/24 hr were significantly greater (p < 0.05 ; p < 0.0005) in pubertal (4.61 ± 0.45; 5.62 ± 0.37) than in prepubertal pts (3.65 ± 0.12; 3.8 ± 0.24) but no differences were noted in pts in gr I. SmC levels ranged from 0.14 to 1.5 U/ml in gr I and from 0.10 to 1.8 U/ml in gr II. No significant differences in SmC levels were found between the 2 groups, however, in both groups the mean SmC level was greater in pubertal than in prepubertal pts. The results indicate that 1) abnormalities in neuroregulation of CH secretion may be a common cause of short stature, 2) GH responses to provocative stimuli and SmC levels are not diagnostic of subtle abnormalities in GH secretion and 3) puberty may augment GH release in children with normal 24 hr GH concentration but appears to have no effect in children with disturbances in CH secretion. Growth response to hGH therapy may elucidate whether dysregulation in GH secretion is a treatable cause of short stature.