AbstractBackground:The association between oxidative stress (OS) and metabolic syndrome (MetS) has been reported in adults. We analyzed the relation between circulating oxidized low-density lipoproteins (Ox-LDL) and MetS in pediatric ages in order to define whether plasma Ox-LDL levels are correlated to obesity and whether oxidative damage, using serum Ox-LDL levels as a proxy, are associated with MetS.Methods:We enrolled 178 children (11.8±2.6 years). On the basis of a body mass index (BMI) threshold, the subjects were classified as: normal weight BMI <75th percentile; overweight BMI 75–97th percentile; obese BMI >97th percentile. Patients were classified as having MetS if they met three or more of the following criteria for age and sex: BMI >97th percentile, triglyceride levels >95th percentile, high-density lipoprotein (HDL) cholesterol level <5th percentile, systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) >95th percentile and impaired glucose tolerance.Results:Obese children showed increased MetS prevalence (p=0.001) and higher Ox-LDL levels compared to normal- and overweight subjects (p<0.05), with a limited relation between Ox-LDL and MetS (p=0.06). Waist-to-height ratio (W/HtR) (p=0.02), triglycerides (TG) (p=0.001) and LDL-cholesterol (p<0.001) resulted independent predictors of increased plasma Ox-LDL levels.Conclusions:Oxidative damage was correlated with a hypertriglyceridemic waist phenotype and can be a precocious marker of MetS and cardiometabolic risk in obese children.