Sex Steroids Increase Spontaneous Growth Hormone Secretion in Short Children

Spontaneous growth hormone (GH) secretion and GH responses to standard provocative tests and to growth hormone releasing hormone (GHRH) were evaluated in twenty-one children with idiopathic short stature. Eight children (two female, six male) were studied after brief sex steroid administration (estradiol or testosterone), whereas thirteen children (seven female, six male) were studied under baseline conditions without sex steroid treatment. Children were prepubertal or in early puberty, with no endocrine abnormalities. Children who were given sex steroids showed a greater frequency of growth hormone pulses during the day (6.0 ±0.3 [SEM] versus 3.2 ± 0.3, p < 0.001) and a higher mean 24-hour growth hormone level (5.4 ± 0.8 vs. 3.6 ± 0.5 ng/ml, p < 0.02) than children who were untreated. GH peak responses to arginine and to L-dopa were higher in treated children (27.3± 5.5 vs. 9.8 ± 1.9 ng/ml, and 11.4 ±3.3 vs. 5.7 ± 2.2 ng/ml, respectively). In contrast, responses to insulin and to GHRH were not different between the two groups. We conclude that sex steroids increase both spontaneous and stimulated GH secretion in children with idiopathic short stature, and that sex steroid induced increases in GH secretion may contribute to the pubertal growth spurt.