Early-onset metabolic syndrome in prepubertal obese children and the possible role of alanine aminotransferase as marker of metabolic syndrome.

INTRODUCTION: Obesity is often associated with increased serum alanine aminotransferase (ALT), and elevation of ALT is a marker of non-alcoholic fatty liver disease which is caused in part by insulin resistance, the essential characteristic of metabolic syndrome (MS). We evaluated the prevalence of MS in prepubertal obese children and the usefulness of ALT as an MS marker. PATIENTS: 120 obese children (6.3 ± 1.6 years old) and 50 normal-weight controls (5.3 ± 2.0 years old) were included. Patients were classified as having MS if they met ≥ 3 of the following criteria: body mass index >97th percentile, triglycerides >95th percentile, high-density lipoprotein cholesterol <5th percentile, systolic (SBP) and/or diastolic (DBP) blood pressure >95th percentile, fasting blood glucose 100 mg/dl and/or impaired insulin sensitivity with homeostasis model assessment for insulin resistance >97.5th percentile. ALT levels were also evaluated.
RESULTS: MS occurred in 16.6% of obese patients. Significant differences were present in body mass index (p < 0.001), SBP (p = 0.002) and DBP (p < 0.001) between non-MS and MS obese patients; laboratory data, except total cholesterol, were significantly different in the two groups. The strongest association with MS (as evaluated by the c-statistic) was found for insulin and homeostasis model assessment for insulin resistance (c = 0.92 and 0.91, respectively); also, DBP and SBP showed good discrimination ability (c = 0.73 and 0.72, respectively). ALT levels in the MS group were higher than in the non-MS group (p = 0.02) and associated with MS (p = 0.001; c = 0.69).
CONCLUSION: MS is a consequence of obesity already in very young children. Also, pathological serum ALT levels were significantly correlated with MS and might be considered a marker for defining MS, though confirmation in a longitudinal study is called for.