Evidence of different actions of testosterone, estradiol, FSH, and LH on the growth axis

To study the possible role of sexual hormones, Testosterone (T), Estradiol (E-2), follicle-stimulating hormone (FSH),;and luteinizing hormone (LH) on the growth axis, we examined the correlations between the sex, growth hormo ne (GH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor b inding protein 3 (IGFBP3), FSH, LH, T and E-2, in growth retarded children ranging in age from 7 to 13 yr. All hormones were measured by Radioimmunoas say (RIA) in a pool of aliquots of samples obtained every 20 min over 12 h (overnight) in each child. Multivariate statistical analysis was performed. We have found: a) That only FSH concentrations were significantly higher i n girls than in boys; b) A positive correlation between T-IGF-1; T-IGFBP3; FSH-LH; FSH-IGF-1; FSH-IGFBP3, LH-IGF-1, LH-IGFBP3 the sex-FSH; and the sex -IGFBP3 c) A high positive correlation between plasmatic E-2 and IGF-1/IGFB P3 ratio (an index of free, active IGF-1). We concluded that the sex, FSH, LH, T and E-2 influence the growth axis. The sex through IGFBP3; LH, FSH, a nd T through IGF1 and IGFBP3; E2 through the IGF-1/IGFBP3 ratio, an index o f active ICE-1.