In developed countries, non-alcoholic fatty liver disease (NAFLD) is the predominant liver disease in adolescents. The main cause of elevated alanine aminotransferase (ALT) in adolescents is NAFLD. This study aimed to estimate the prevalence of elevated ALT in healthy Korean adolescents and to identify the prevalence of metabolic-related diseases and factors associated with elevated ALT. Methods: We used data from the Korea National Health and Nutrition Examination Survey (KNHANES) VII. The

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... le comprised 1,417 adolescents (745 boys and 672 girls) aged 12 to 18 years. Logistic regression analysis was performed to identify risk factors for elevated ALT. Results: Out of the 1,417 adolescents, 3.95% were estimated to have elevated ALT. In the group with elevated ALT, the prevalence of hypertension, diabetes, high triglyceride (TG), and low high-density lipoprotein cholesterol (HDL-C) was 42.9%, 5.2%, 20.8%, and 44.0%, respectively. This was significantly higher than in the group without elevated ALT (P<0.001). Multiple logistic regression analysis revealed that elevated ALT was strongly associated with obesity (odds ratio, 15.41; 95% confidence interval [CI], 7.28-32.59) and overweight (odds ratio, 4.02; 95% CI, 1.44-11.23) compared to normal weight (P-value 0.008). Moreover, fasting blood glucose was associated with elevated ALT in adolescents. Conclusion: Elevated ALT was associated with obesity and obesity-related diseases such as hyperglycemia and low HDL-C. Therefore, it is important to manage adolescent obesity, which is a major risk factor for elevated ALT.