Investigation Of Serum Leptin Concentrations In Healthy Children And In Children With Anorexia

Objective: Leptin,the obese gene product ,is a peptide hormone synthesized and sereted by adipocytes.The main physiological actions of leptin is to inform the central nervous system about the state of nutritions,then to restrain appetite ,reduce food intake and increase energy expenditure in order to regulate energy homeostasis.Recent studies have shown a correlation between serum leptin concentration and body weight,body fat mass and serum insulin levels, et al. Discussions of serum leptin in children have not been reported in Chinese literature. In recent years,the morbidity of children with anorexia is accending obviously,especially in urban.lt has been one of the common diseases in pediatrics.The pathogenesis of anorexia remains poorly understood. Discussions of the relationship between leptin and anorexia have not been reported in domestic studies. Our study measured the serum leptin levels in 1-14 years old healthy children and investigated the relationship between leptin and body mass index, gender and age. We also measured the serum concentrations of leptin, thyroid hormones , zinc, iron and copper in 1-10 years old childrenwith anorexia,in order to investigate the role of leptin in the pathogenesis of anorexia.Methods: The study subjects consisted of 67 healthy children(36 males and 31 females,age l-14yr) and 54 children with anorexia(31 males and 23 femsles,age 1-1 Oyr). Circulating leptin concentrations were measured by IRMA in healthy children ,and the relationship between serum leptin levels and BMI [body weight(kg)/height X height(m2)] , gender and age were analysed. At the same time,the serum leptin levels in anorectics were measured and compared with that of normal children in the same age and gender group. Serum T3,T4,zinc,iron and copper were measured and compared between normal children and anorectics. The correlationship between leptin and zinc,T3,T4 were evaluated.Results: The serum leptin concentrations in normal children were 3.42 + 2.6 u g/L in boys and 7.71 +6.15 u g/L in girls,which was about 1 time higher in girls than in boys. In both boys and girls, leptin leveles were significantly correlated with BMI(r=0.73,P<0.001 in male and r=0.81,P<0.001 in female).In girls(l-14yr of age) leptin levels increased with age.In boys leptin levels also tended to increase with age in subjects of 1-10 yr of age,while decreased in ll-14yr of age.In anorectics,they were 1.14+ 0.99 u g/L in male and 1.93 +1.13 u g/L in female.They were lower significantly than that of normal children hi the same age and gender group(P<0.001). And there was no significantlinear correlation between leptin and BMI(r=0.12 in male and r=0.2 6 in female).There were significant linear correlations between leptin and zinc,T3,T4,but not with iron and copper.Conclusions: Leptin is a kind of hormone which can regulate appetite and energy metabolism.Our study provided the serum leptin concentrations of 1-14 yr healthy children primarily.lt was correlated with BMI,gender and age. The serum leptin concentrations in anorectics were lower significantly than that of normal children. The serum levels of zinc,iron,T3 and T4 were also lower significantly. It can be concluded that leptin and zinc,thyroid hormone were involved in the pathogenesis of anorexia.