Non-alcoholic fatty liver disease (NAFLD) has been recognized as an important childhood liver disease, especially where the prevalence of childhood obesity is increasing. The purpose of this study is to clarify the usefulness of elevated serum aminotransferase activities and their ratio for predicting the presence of fatty liver and its severity in obese children.

Forty-four children (M/F 29/15, age 4 to 16 years) with obesity (weight excess>20%) were analyzed retrospectively with medical records based on degree of obesity, bioelectrical impedence, serum aminotransferase activities, lipid profiles and ultrasonography.

1) Ultrasonography was carried out in 34 cases. Elevated serum ALT was found in 89.7% (26/29) of the patients diagnosed as fatty liver by ultrasonography and decreased AST/ALT ratio (<1) was found in 96.6% (28/29). There was a strong correlation between elevated serum ALT (>45 IU/L) or decreased AST/ALT ratio (<1) and the fatty liver in obese children (p<0.05). 2) There was no significant correlation between the serum ALT or AST/ALT ratio and the degree of fatty liver (p>0.05). 3) There was a significant correlation between total cholesterol, triglyceride and fatty liver (p<0.05).

Serum ALT activity and AST/ALT ratio were useful to predict the presence of fatty liver diagnosed by ultrasonography in obese children, whereas they were not useful to predict the degree of fatty liver. Therefore, to prevent fatty liver progressing to advanced liver disease, it is necessary to manage and monitor the obese children continuously, especially those who have predicting factors of fatty liver.