Relationship between alanine aminotransferase levels and metabolic syndrome in nonalcoholic fatty liver disease

Objective: To investigate the relationship between alanine aminotransferase (ALT) levels and metabolic syndrome (MS) in nonalcoholic fatty liver disease (NAFLD). Methods: A total of 26527 subjects who received medical health checkup in our hospital from January 2005 to July 2007 were enrolled in the study. The diagnosis of fatty liver was based on ultrasound imaging. MS was defined according to the criteria of the Adult Treatment Panel III. ALT, triglyceride (TG), high density lipoprotein cholesterol (HDL-c), fasting plasma glucose (FPG), height, weight, waist circumference (WC), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured in each subject to analyze the relationship between MS and ALT activity. Results: (1) The prevalence of NAFLD in men (30.94%) was significantly higher than that in women (15.65%); (2) The incidence of MS in NAFLD (33.83%) was significantly greater than that in non-NAFLD (10.62%); (3) Of the 6470 subjects with NAFLD, in the age-adjusted partial correlation analysis, there were statistically significant correlations between the ALT levels and most metabolic risk factors in each sex (P < 0.01), except that ALT levels had no correlation with HDL-c in women. Moreover, in the multiple stepwise regression analysis, SBP lost its significance, and WC, body mass index (BMI), age, DBP, TG and FPG were independently associated with ALT levels in both sexes (P < 0.05). HDL-c remained significant and was independently related to ALT levels in men; (4) ALT levels were significantly higher in subjects with MS compared to those without MS (P < 0.001). Mean ALT levels increased with the number of MS components in each sex (P < 0.05 for trend). Conclusion: We found a strong relationship between ALT levels and MS in NAFLD and revealed that the cluster of MS components might be the predictor for ALT elevations.