Abstract and Introduction
Abstract
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.
Introduction
Obesity is an important risk factor for liver injury. A central fat distribution may be more important than total adipose mass. In the general population, liver injury has been associated with anthropometric measures, such as body mass index (BMI) and waist circumference. Although this relationship is presumed to be determined by fat mass, a limitation of BMI and other anthropometric measures is that they reflect both fat and lean mass. The relationship of liver injury with body mass components using actual measures of body composition, such as dual x-ray absorptiometry (DXA), has not been evaluated in a population-based study. We examined the individual and relative contributions of body composition, measured with DXA, to elevated serum alanine aminotransferase (ALT) among US adults without evidence of chronic viral hepatitis in a national population-based sample.