SERUM LEPTIN THROUGH CHILDHOOD AND ADOLESCENCE

OBJECTIVE Leptin is the protein product of the recently cloned ob gene , that has been implicated in the control of body weight and thermogen esis, but also independently stimulates the reproductive axis. As majo r changes in body composition and gonadal function occur during human adolescence, we have assessed serum leptin concentration through child hood, SUBJECTS AND MEASUREMENTS Serum leptin was measured in a radioim munoassay in samples from 235 healthy children from 5 to 18 years of a ge, Its; relationship to body mass index (BMI) (expressed as standard deviation score (SDS)) and the changes in concentration both within an d between sexes over the stages of puberty were analysed, RESULTS Seru m leptin was present at similar concentrations in both sexes over the prepubertal years and increased in parallel into early puberty (breast stage (B) 2, genital stage (G) 2), Thereafter serum leptin in the boy s declined to a nadir in G5, In contrast in girls, leptin remained con stant in mid-puberty rising to a peak at B5. Factors influencing lepti n (BMI SDS, age and testicular volume) were assessed therefore in the pre- and peripubertal stages (B1-2, G1-2) compared to the later pubert al stages (B3-5, G3-5), In all groups, leptin was positively correlate d to BMI SDS (r(2)=38-41% in girls, r(2)=31-35% in boys), However in B 1-2 and G1-2, leptin was also positively related to age, which contrib uted a further 27% and 20% respectively to the variability, In B3-5, a ge only accounted for an additional 5% in leptin variability. In contr ast in G3-5, leptin was related positively to BMI SDS (r(2)=35%) and n egatively to testicular volume (r(2)=24%). CONCLUSIONS The influence o f BMI on leptin is a significant factor throughout the prepubertal and pubertal years of both sexes, The additional negative effect of testi cular volume in the boys contributes to the sexual dichotomy in leptin concentration at the completion of puberty, The similar rise in lepti n over the prepubertal years into early puberty in both sexes, related not only to BMI SDS but also independently to age, would suggest that leptin may have a facilitatory role in human pubertal development.