Serum Alanine Aminotransferase Independently Correlates with Intrahepatic Triglyceride Contents in Obese Subjects

Liver enzymes including serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT) are well recognized as surrogate makers reflecting non-alcoholic fatty liver disease (NAFLD). However, the associations of serum ALT, AST and GGT with hepatic lipid contents are not well established. The aim of this study was to investigate the relationship between liver enzymes and intrahepatic triglyceride (IHTG) contents, and explore the feasibility in using liver enzymes to reflect accumulation of IHTG in obese subjects. A cross-sectional analysis was conducted in 475 obese adults aged 40-65 years. Anthropometric parameters and blood biochemical indexes including liver enzymes, glucose and lipid profiles were measured. The liver triglyceride contents of subjects were determined by H-1-MRS. Serum ALT, AST and GGT were positively correlated with IHTG contents (p < 0.01). Serum ALT, AST and GGT levels at the highest quartile of IHTG contents were significantly elevated as compared with those in the lowest quartile (p < 0.01). Multivariate linear regression analysis demonstrated that serum ALT, but not AST or GGT was independently associated with IHTG contents. By logistic regression analysis, the odds ratio for higher IHTG contents was increased by 1.464 times/1 SD increase in serum ALT level after adjusting for multiple confounding factors [OR (95 % CI) 2.464 (1.584-3.834)]. However, these relationships could not be observed between serum AST or GGT with IHTG contents. Serum ALT level is independently correlated with the hepatic triglyceride contents in obese subjects and more appropriate to be used as a predictor for the degree of NAFLD rather than AST and GGT.