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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]