Objectives: (1) To determine the prevalence of abnormal liver enzymes in overweight and obese adolescents and (2) to determine the relationship of alcohol ingestion and serum antioxidants to the presence of abnormal liver enzymes in overweight and obese adolescents.
Methods: Serum alanine aminotransferase (ALT) and gamma-glutamyl transpeptidase levels were measured in 2450 children between the ages of 12 and 18 years, enrolled in the National Health and Examination Survey, cycle III (NHANES III). Obesity was defined as a body mass index >95th percentile for age and sex. Overweight was defined as a body mass index >85th percentile for age and sex. Nutritional intake was assessed by 24-hour dietary recall and food frequency questionnaires. Serum antioxidants were measured by high-pressure liquid chromatography.
Results: Sixty percent of adolescents with elevated ALT levels were either overweight or obese. Overall, 6% of overweight adolescents had elevated ALT levels (odds ratio: 3.4 [95% CI: 3.5-12.8]). Ten percent of obese adolescents had elevated ALT levels (odds ratio: 6.7 [95% CI: 3.5-12.8]). In addition, approximately 1% of obese adolescents demonstrated ALT levels over twice normal. Approximately 50% of of obsese adolescents who reported modest alcohol ingestion (4 times per month or more) had elevated ALT levels (odds ratio: 10.8, 95% CI: 1.5-77). Other factors associated with elevated ALT levels in overweight and obese adolescents include increased age, elevated glycolated hemoglobin, elevated triglycerides, and decreased levels of serum antioxidants-vitamin E, beta-carotene, and vitamin C.
Conclusion: Overweight and obesity are the most common findings in adolescents with elevated ALT levels. Even modest alcohol consumption may significantly increase the likelihood of obese adolescents developing obesity-related liver disease.