The association between non-alcoholic fatty liver disease and carotid atherosclerosis in subjects with within-reference range alanine aminotransferase levels.

Our aim was to investigate whether the evaluation of non-alcoholic fatty liver disease (NAFLD) by ultrasound provides additional benefit in assessing carotid atherosclerotic burden in subjects with alanine aminotransferase (ALT) concentrations within the reference range. This was a cross-sectional analysis of 769 healthy individuals (326 men and 443 women) with an ALT concentration ≤ 40 IU/L and alcohol consumption < 140 g/week. Mean carotid artery intima-media thickness (C-IMT) was measured using ultrasound. NAFLD was defined as a mild or greater degree of hepatic steatosis on ultrasound. Although all subjects had an ALT concentration within the reference range, the prevalence of NAFLD increased with increasing quartiles of ALT concentration (27.1%, 40.0%, 54.7%, 75.3% in men, P for trend < 0.001; 22.0%, 34.4%, 35.7%, 55.0% in women, P for trend < 0.001). In the 3rd and 4th quartiles of ALT concentration, women with NAFLD had a significantly higher C-IMT than those without NAFLD (0.671±0.019 mm vs. 0.742±0.025 mm, P=0.023 in Q3; 0.651±0.023 mm vs. 0.737±0.021 mm, P=0.005 in Q4). These differences remained significant even after adjusting for a broad spectrum of potential confounders. In contrast, although men with NAFLD tended to have a higher C-IMT than those without NAFLD in each quartile, these differences were not statistically significant. Women with an upper normal range ALT concentration showed increased C-IMT only when they had NAFLD. Therefore, in women with an elevated ALT level within the reference range, further evaluation for NAFLD, such as liver ultrasound, could potentially identify those patients at high risk for cardiovascular disease.