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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. Copyright © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Early onset of breast development in a young girl is usually a benign and isolated prepubertal condition, i.e., premature thelarche (PT), but can sometimes be progressive and the first sign of pubertal precocity (PP). Serum 17β-estradiol (17β-E2) level is a possible marker to differentiate between benign and pathological forms of breast development. We defined an upper serum 17β-E2 level for benign, “classic” PT for girls aged 9–48 months. Methods: Serum 17β-E2 was analysed with a highly sensitive extraction radioimmunoassay (RIA). Gonadotropins, Tanner breast stage, growth, other investigations, and clinical outcome were assessed in 125 girls with breast development, in a population-based study in West Sweden. Results: A total of 125 of 128 girls had a benign form of breast development with a mean serum 17β-E2 level of 15.2 pmol/L and a mean + 2 SD of 31 pmol/L, which was regarded as the upper limit for benign PT; 3 girls with PP had 17β-E2 levels above 70 pmol/L. Conclusion: This is the first study to define an upper serum 17β-E2 level associated with benign PT. Girls aged 9–48 months with PT and Tanner breast stage 2 have 17β-E2 levels below 32 pmol/L using extraction RIA. LH below the detection limit (0.1 IU/L) and measurable FSH support benign PT. [ABSTRACT FROM AUTHOR]

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. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]