Non-alcoholic fatty liver disease in obese children evaluated by magnetic resonance imaging.

Aim: To investigate the prevalence of non-alcoholic fatty liver disease (NAFLD) in a group of obese children (BMI> 97th %) and to establish correlations between the severity of hepatic fatty infiltration, auxological findings and parameters of insulin resistance. Methods: 44 obese children, aged 6–16 years, with a BMI above the 97th centile were selected for analysis. Hepatic fat content was assessed by phase contrast MRI. Demographic data included weight, height, body mass index, body fat mass and waist circumference. Blood tests included fasting blood glucose, fasting insulin and lipid profile. Insulin sensitivity was evaluated with QUICKI. Results: Elevated hepatic fat fraction (FF) was identified in 14 subjects (31.8%; 0.07 SEM). Children with fatty liver (FF > 9%) had higher ALT (P<0.0001), AST (P=0.002) and triglycerides (P=0.008) values compared to the children without NAFLD. All the children showed a decreased insulin sensitivity (P<0.0001), but no difference was found between children with or without NAFLD. The degree of liver fatty infiltration was positively correlated with ALT (P<0.0001), AST (P<0.002) and γGT (P<0.0001), with height (P<0.006) and BMI (P<0.05) but not with estimates of body fat mass or fat distribution. Conclusion: Obese children are frequently affected by NAFLD, which cannot be predicted by clinical and/or anthropometrical findings. There is however a strict correlation between the degree of liver fatty infiltration and elevation of liver enzymes.