Relationship between body mass index and alanine aminotransferase concentration in non-diabetic Korean adults

Background/Objectives: Obesity has been identified as an important factor of elevated alanine aminotransferase (ALT), a surrogate of non-alcoholic fatty liver disease. We investigated the relationship between obesity and elevated ALT in the general Korean population.Subjects/Methods: The study sample was comprised of 3098 Korean adults who had participated in the 2005 Korean National Health and Nutrition Examination Survey. Obesity was assessed using body mass index (BMI). Overweight (23≤BMI<25) and obese (BMI≥25) were defined by the International Obesity Task Force for Asian adults. ALT was measured by enzymatic methods. Elevated ALT was defined as an enzyme activity >40 IU/l for men and >31 IU/l for women. Results: Among participants, 246 (12.7%) men and 86 (7.4%) women displayed elevated ALT. BMI was significantly higher in men and women with elevated ALT than those with normal ALT (P<0.0001). The unadjusted odds ratio (OR) for elevated ALT increased according to the degree of BMI in men (OR: 1.9, 95% confidence interval (CI): 1.25-2.93 in overweight vs OR: 5.01, 95% CI: 3.49-7.21 in obese; P<0.0001) and women (OR: 2.44, 95% CI: 1.24-4.82 vs OR: 3.94, 95% CI: 2.18-7.13; P<0.0001). This trend did not differ after adjustment for putative risk factors including alcohol intake in men (OR: 1.56 vs OR: 3.47, P<0.0001) and women (OR: 1.55 vs OR: 3.10, P=0.0015). Conclusion: BMI is implicated as a strong risk factor of elevated ALT in non-diabetic Korean adults.