Trunk Fat Is Associated With Increased Serum Levels of Alanine Aminotransferase in the United States

Background & Aims

Liver injury is associated with obesity and related measures, such as body mass index (BMI) and waist circumference. The relationship between liver injury and body composition has not been evaluated in a population-based study.

Methods

Using data from a US population-based survey, we examined the contributions of body composition, measured by dual-energy x-ray absorptiometry (DXA), to increased serum alanine aminotransferase (ALT) activity among 11,821 adults without viral hepatitis. Trunk fat, extremity fat, trunk lean, and extremity lean mass were divided by height squared and used to categorize subjects into quintiles; logistic regression odds ratios (OR) were calculated for increased ALT.

Results

Increased ALT was associated with higher measures of fat and lean mass (P < .001) after adjustment for alcohol consumption and other liver injury risk factors in separate models for each DXA measure. Trunk fat was associated with increased ALT (P ≤ .001) in models also including any 1 of the other 3 measures. Extremity fat was independently inversely associated among women (P < .001). Trunk and extremity lean mass were not independently related to increased ALT. In models that contained all 4 DXA measures, the OR (95% confidence interval [CI]) for increased ALT for the highest, relative to lowest, quintile of trunk fat/height squared was 13.8 (95% CI: 5.4−35.3) for men and 7.8 (95% CI: 3.9−15.8) for women. When BMI, waist circumference, and trunk fat were considered together, only trunk fat remained independently associated with increased ALT.

Conclusions

Trunk fat is a major body composition determinant of increased ALT, supporting the hypothesis that liver injury can be induced by metabolically active intraabdominal fat.

Keywords: Alanine aminotransferase, Body composition, Dual-energy x-ray absorptiometry, National Health and Nutrition Examination Survey

Abbreviations used in this paper: BMI, body mass index, CI, confidence interval, DXA, dual-energy x-ray absorptiometry, NHANES, National Health and Nutrition Examination Survey, OR, odds ratio