Background/Aims: To study serum testosterone and estradiol in healthy boys in relation to growth during puberty up to peak height velocity (PHV). Methods: Growth velocity was analyzed through testosterone (n = 41) and 17β-estradiol (n = 37) 24-hour profiles in a dose-response model. Participants were 26 healthy boys admitted for short or tall stature or participating as healthy volunteers at the Queen Silvia Children's Hospital. Other inclusion criteria included the following: gestational age 37-42 weeks, birth weight and length >-2 standard deviation score (SDS) and prepubertal height and weight within ±3 SDS. Testosterone was measured using a modified radioimmunoassay (RIA) with a detection limit of 0.03 nmol/l. Estradiol was determined using an ultrasensitive extraction RIA with a detection limit 4 pmol/l. A sixth-grade polynomial was fitted to each child's growth data, giving growth velocity and age at PHV. Results: Growth velocity increased by 50% from prepubertal growth to PHV at a morning testosterone level of 3.1 nmol/l (95% confidence interval 2.4-4.2), EC₅₀. The corresponding EC₅₀ of 17β-estradiol was 6.5 pmol/l (3.2-13). Boys approaching PHV (<4% remaining) had morning testosterone levels >10 nmol/l and 17β-estradiol >9 pmol/l. Conclusion: Observed early puberty/initial mid puberty morning testosterone levels of 2.4-4.2 nmol/l are associated with a 50% increase in growth velocity from prepubertal growth to PHV in healthy boys.

Aim: The objective of this study was to determine estradiol levels and assess their relationship to pubertal growth in girls. Methods: Thirty-seven 24-hour profiles of serum 17β-estradiol were retrospectively analyzed in relation to growth in 27 healthy girls admitted for short/tall stature (n = 20) or recruited as healthy volunteers at Göteborg Pediatric Growth Research Center (GP-GRC). Inclusion Criteria: Birth weight and length above –2 SDS, gestational age 37–42 weeks, prepubertal height and weight within ±3 SDS and normal growth hormone secretion. Serum estradiol was determined by a validated ultrasensitive extraction radioimmunoassay (detection limit 4 pmol/l). A sixth-grade polynomial was fitted to each girl’s growth data. Growth velocity and age at peak height velocity (PHV) was calculated. Results: A dose-response model was used to find the morning 17β-estradiol level at which half of the maximal pubertal growth up to PHV had occurred, EC₅₀, which was 20 pmol/l with a 95% confidence interval of 13–31. When 17β-estradiol exceeds early pubertal levels (Tanner breast stage 2, 10–51 pmol/l), less than 25% of the potential pubertal growth velocity up to PHV remains. Conclusions: Morning 17β-estradiol in the low early pubertal range (13–31 pmol/l) is associated with increasing growth velocity.

Aim: To study the influence of growth hormone (GH) treatment on the initiation and progression of puberty in short children. Methods: This prospective, randomized, controlled study included 124 short children (33 girls) who received GH treatment (Genotropin®; Pfizer Inc.) from a mean age of 11 years until near adult height [intent-to-treat (ITT) population]. Children were randomized into three groups: controls (n = 33), GH 33 µg/kg/day (n = 34) or GH 67 µg/kg/day (n = 57). Prepubertal children at study start constituted the per-protocol (PP) population (n = 101). Auxological measurements were made and puberty was staged every 3 months. Serum sex-steroid concentrations were assessed every 6 months. Results: No significant differences were found between the groups, of both PP and ITT populations, in time elapsed from start of treatment until either onset of puberty, age at start of puberty or age at final pubertal maturation in either sex. In the ITT population, pubertal duration was significantly longer in GH-treated girls, and maximum mean testicular volume was significantly greater in GH-treated boys than controls, but there were no differences in testosterone levels between the groups. Conclusion: GH treatment did not influence age at onset of puberty and did not accelerate pubertal development. In boys, GH treatment appeared to increase testicular volume.

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