ObjectiveTo investigate the relationship between leptin concentrations, gonadotropic hormone concentrations, and body composition during puberty in a Dutch children cohort.DesignIn a cohort of 98 children, we determined anthropometric measurements, body composition, and concentrations of leptin, FSH, and LH.ResultsSex differences were observed from Tanner stage 1 onwards in weight, body fat percentage, and leptin/fat mass ratio. In boys and girls, the relationship between leptin concentrations

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... nd FM was weaker at Tanner stage 2 (R2=0.33 and R2=0.39; P<0.001), 3 (R2=0.27 and R2=0.36; P<0.002), and 4 (R2=0.21 and R2=0.28; P<0.03) than at Tanner stage 1 (R2=0.51 and R2=0.67; P<0.001) and 5 (R2=0.46 and R2=0.78; P<0.01). In girls, a peak in leptin concentrations (8.5±6.0 ng/ml) preceded a peak in LH and FSH concentrations (15.1±3.5 and 5.0±4.5 IU/l). A lead/lag relationship was observed of leptin at Tanner stage 1 to LH and FSH at Tanner stage 2 (R2=0.12, P<0.05 and R2=0.18, P<0.05). In boys, there was no peak in leptin, LH, and FSH; additionally, leptin at Tanner stage 3 was related FSH at Tanner stage 4 (R2=0.17, P<0.04).ConclusionIn boys and girls during puberty, factors independent of fat mass become (transiently) more important in the regulation of plasma leptin concentrations. Moreover, in girls, leptin is suggested to act as a permissive factor for the onset of puberty, while, in boys, leptin has a different timing and possibly different function.