RESUMO
BACKGROUND/AIMS: The metabolic syndrome (MS) is associated with insulin resistance (IR), inappropriate fibrinolysis and high plasma leptin concentrations. The aim of this study was to quantify fibrinolysis and MS-related variables in obese prepubertal children and to evaluate changes in these variables as a result of improved body mass index (BMI), IR and leptin levels following 9 months of treatment. METHODS: The homeostasis model assessment for insulin resistance (HOMA-IR), leptin, plasminogen activator inhibitor-1 (PAI-1) and lipid profile were studied at baseline in obese (n = 50) and nonobese children (n = 50), and after 9 months of treatment in obese children. RESULTS: In the cross-sectional study the mean values for insulin, HOMA-IR, triglycerides, leptin and PAI-1 were significantly higher in obese children than in controls. High-density lipoprotein cholesterol (HDLc) and apolipoprotein A-1 were significantly lower. In the longitudinal study, after 9 months, children with lowered BMI standard deviation score displayed a significant decrease in insulin, HOMA-IR, PAI-1, leptin and triglyceride levels, and an increase in HDLc. Only leptin proved to be an independent predictive factor for changes in PAI-1 (p = 0.010). CONCLUSION: Obesity-linked disorders appear in obese children prior to puberty; these disorders can be improved by decreasing BMI. Changes in leptin levels were found to independently predict changes in PAI-1 in obese children and can help to diagnose complications associated with the obesity.