Growth hormone secretion patterns in relation to LH and estradiol secretion throughout normal female puberty

Abstract

Pulsatile growth hormone secretion patterns were studied in relation to luteinizing hormone and estradiol release in 33 healthy (pre)pubertal girls. Plasma GH was determined every 10 min, plasma LH and E2 every hour. Night-time GH release was always higher than daytime GH release. During daytime, all GH secretion parameters, except for the basal GH level, increased significantly from the prepubertal stage to stage B4 before (m-) the menarche (p = 0.05) and decreased thereafter (p = 0.05). During night-time, mean GH level and the fraction of GH in pulses also tended to increase from stage B1 to stage B4m-. The number of high pulses (greater than 8 micrograms/l) during day and night together tended to increase until stage B4m- and decreased after the menarche (p = 0.05). Height velocity did not correlate with the number of high pulses (Kendall tau = 0.14, p = 0.14). From stage B1 to B4m- high correlations were observed between E2 levels and GH secretion parameters, particularly during the day (tau = 0.59-0.71, p less than or equal to 0.01). The correlations between LH levels and GH secretion were high as well (tau = 0.50-0.81, p less than or equal to 0.01), but equal during day and night. It is concluded that during puberty 1. spontaneous GH release in girls increases 2-3 fold until the menarche and decreases thereafter, primarily as the result of an increasing and decreasing GH pulse amplitude; 2. diurnally increasing estradiol levels correlated with increasing GH secretion.