Effect of sex hormone administration on circulating ghrelin levels in peripubertal children

Background: Ghrelin levels gradually decrease throughout childhood and with advancing pubertal stage. The change during puberty is more pronounced in boys than girls. Objective: The objective of the study was to investigate whether the pubertal drop in ghrelin secretion is modified by the increase in sex hormones. Patients and Methods: Ghrelin levels were measured in 34 short peripubertal children (17 boys and 17 girls) aged 8-12.5 yr before and after sex hormone priming for GH stimulation testing. Results: In boys, priming with testosterone increased testosterone to pubertal levels (23.7 ± 7.1 nmol/liter), which in turn induced a marked decrease in ghrelin (from 1615.8 = 418.6 to 1390.0 = 352.0 pg/ml) and leptin (from 8.0 ± 4.5 to 5.8 = 3.2 ng/ml) and an increase in IGF-I (from 162.7 ± 52.8 to 291.1 ± 101.6 ng/ml) (P < 0.001 for all parameters). In girls, priming with estrogen led to a supraphysiological increase in estradiol levels (1313.8 ± 438.0 pmol/liter), which had no effect on ghrelin, leptin, or IGF-I. There was no correlation between ghrelin levels and levels of sex hormones, leptin, or body mass index in either boys or girls. Conclusions: A pharmacological increase in sex hormones is associated with a marked decline in circulating levels of ghrelin in boys but not girls. Additional longitudinal studies through puberty are needed to elucidate the physiological interaction between sex hormones and ghrelin.