Body mass index is a stronger predictor of alanine aminotransaminase levels than alcohol consumption

Abstract

The relative effects of obesity compared to alcohol on liver injury are uncertain. We examined their effects on alanine aminotransferase (ALT) and gamma glutamyltransferase (GGT) levels in a population-based cohort. Adult residents (2610: 1326 males, 1284 females) from Busselton, Australia, participated in a cross-sectional survey determining alcohol intake as determined by a validated questionnaire, anthropometric measurements and serum analysis. Alcohol consumption was classified as never, light (420 g/week). The majority of subjects were either overweight (41%) or obese (17%). A minority of subjects were moderate (25%) or heavy drinkers (4%). Body mass index (BMI) and waist circumference were strongly associated with ALT and GGT (P < 0.0001 for all tests). Alcohol consumption was modestly associated with ALT in females (P = 0.01) but not in males (P = 0.9). In contrast, GGT was significantly associated with alcohol in both genders (P < 0.0005). The risk of an elevated ALT was seven-fold higher with obesity but only two-fold higher with moderate or heavy alcohol use. Obesity accounted for half of all elevated ALT levels in the cohort, whereas alcohol excess was responsible for less than 10%. No synergistic effect was observed between BMI or waist circumference and alcohol on ALT or GGT (P > 0.2 for all tests). Excess weight is more common than excessive alcohol consumption in the community and confers a greater risk of elevated aminotransaminase levels.