Leptin levels show diurnal variation throughout puberty in healthy children, and follow a gender-specific pattern

Objective: To investigate the levels and diurnal rhythm of serum leptin in healthy children. and to investigate the association between leptin levels and sex steroids. Methods: Four girls and four boys, all healthy volunteers. were followed lo ngitudinally throughout puberty. Their chronological ages ranged from 8.7 t o 19.5 years, and body composition, expressed as weight-for-height standard deviation scores (SDS), ranged between -1.7 and +2.4. Serum leptin, oestra diol and testosterone concentrations were measured by radioimmunoassay at 1 000, 1400. 1800, 2200, 0200 and 0600 h. Results: In all. girls and boys, both prepubertally and during pubertal dev elopment, serum leptin levels increased during the night, with no differenc e in relative peak amplitude. In boys, the leptin concentrations increased until the initiation of puberty and then declined, whereas in girls. the co ncentrations increased throughout puberty. The inter-individual variation i n mean leptin levels among girls decreased to 11% at the time of menarche. A positive correlation was found for both oestradiol and testosterone versu s leptin in girls throughout puberty (r= 0.64 and r = 0.71 respectively, P < 0.001). A negative correlation was found between leptin and testosterone in boys in mid- and late puberty (r = -0.66, P < 0.01). No correlation was found between oestradiol and leptin in boys or between testosterone and lep tin in pre- and early pubertal boys. Conclusion: Serum leptin concentrations show diurnal variation throughout p ubertal development in both girls and boys. The changes in leptin levels du ring puberty follow a gender-specific pattern. probably due to an influence of sex steroids on leptin production.