Relationship between high plasma leptin concentrations and metabolic syndrome in obese pre-pubertal children

OBJECTIVE: To evaluate the relationship between serum leptin levels and metabolic syndrome, fasting insulin level and anthropometric index in obese pre-pubertal children. DESIGN: A cross-sectional study was carried out on obese children. SUBJECTS: A study was made of 41 obese children (aged 6-9 y) and the same number of non-obese children (control group), matched by age and sex. METHODS: Body mass index (BMI), waist/hip ratio (WHR) and blood pressure were determined in each child. Serum leptin, glucose, insulin, lipid profile, sex hormone binding globulin (SHBG), plasminogen activator inhibitor-1 (PAI-1), tissue-plasminogen activator (t-PA) and fibrinogen were all measured. RESULTS: The serum leptin level was significantly higher in obese children (15.47 vs 4.73 ng/ml). In the obese group, leptin showed a positive correlation with BMI (P < 0.001), insulin (P < 0.001), triglycerides (P < 0.05), PAI-1 (P < 0.05) and t-PA (P < 0.05), and correlated negatively with SHBG (P < 0.01), apolipoprotein A-1 (P < 0.05) and high-density lipoproteins cholesterol (HDL-C) (P < 0.05). Corrected for BMI and WHR, leptin (P partial = 0.002) is only an independent predictive factor for basal insulin. Using multivariant regression analysis, only insulin (P partial = 0.003) and BMI (P partial = 0,018) were independent predictive factors for leptin. CONCLUSION: For this age group, high leptin resistance may be another component of metabolic syndrome, and may be involved in its etiopathogenesis. The involvement of leptin in this syndrome may be indirect, modulating the insulin's action.