LEPTIN PLASMA-LEVELS IN HEALTHY SPANISH CHILDREN AND ADOLESCENTS, CHILDREN WITH OBESITY, AND ADOLESCENTS WITH ANOREXIA-NERVOSA AND BULIMIA-NERVOSA

Objectives: (1) To investigate normal circulating levels of leptin in children at various stages of pubertal maturation (Tanner stages) acco rding to sex; and (2) to analyze serum leptin levels in pediatric pati ents with eating disorders (obesity, anorexia nervosa, and bulimia ner vosa). Study design: Fasting leptin levels were studied in normal heal thy boys and girls throughout development, Obese pediatric subjects an d patients with anorexia nervosa were studied at the time of diagnosis and after 6 months and 1 year of treatment for weight reduction or we ight recuperation, respectively. Patients with bulimia nervosa were st udied at the moment of diagnosis, Results: Leptin levels in both boys and girls vary significantly depending on the maturational stage, bein g low in both sexes at Tanner stage I and rising significantly by Tann er stage III. In girls, there was a further increase by Tanner stage V and a significant decrease in boys, resulting in a sexual dimorphism in Tanner V subjects, In obese prepubertal patients, leptin levels wer e significantly elevated at the time of diagnosis and declined signifi cantly with weight loss (ANOVA: p < 0.0001). In anorexia nervosa patie nts' leptin levels are significantly reduced compared with age-and sex -matched controls (p < 0.0001). These levels remain significantly lowe r even after recovery of at least 10% of the original body weight and 1 year later. In patients with bulimia leptin levels were reduced at t he time of diagnosis but were significantly higher than in patients wi th anorexia. Conclusion: In normal pediatric subjects leptin levels ar e highly correlated with the body mass index, but this is not the case in eating disorders, where the body mass index is either significantl y elevated or reduced. Both age and sex should be taken into considera tion when analyzing serum leptin levels.