The prevalence of obesity and nonalcoholic steatohepatitis(NASH) was increased in adolescents. This study was performed to observe the prevalence of elevated aminotransferase levels in adolescents and to assess the correlations between aminotransferase levels and obesity related parameters( body mass index, waist circumference, hip circumference, waist to hip ratio and insulin level).

We obtained weight, height, waist circumference and hip circumference from 2,417 male and 1,219 female adolescents. Mean age was 15.7±0.7 years old. We measured fasting insulin, aspartate aminotransferase(AST) and alanine aminotransferase(ALT). Obese and overweight were defined as body mass indices(BMI) of more than the 95th, and 85th-94th percentiles, respectively, for age and sex.

The number of adolescents with obesity is 324(8.9 percent). 414(11.4 percent) subjects belonged to the overweight group. The average ALT level of obese, overweight and control groups were significantly different(obese : 32.1±34.3 U/L, overweight : 19.6±13.6 U/L, control : 12.7±6.7 U/L, P <0.001). The average AST level was also different according to group(obese : 27.8±16.5 U/L, overweight : 22.8±8.6 U/L, control : 20.8±8.5 U/L, P <0.001). AST and ALT were correlated with anthropometric parameters and insulin level. After multiple regression analysis, waist circumference was the significant predictive value for AST(r=0.234, P <0.001). Waist circumference, BMI and insulin levels were significant predictive values for ALT(r=0.435, P <0.001).

The prevalence of abnormal aminotransferase was higher in the obese and overweight groups than control group. Waist circumference was useful to predict abnormal aminotransferase levels.