Clinical and histologic spectrum of nonalcoholic fatty liver disease associated with normal ALT values

Abstract

A retrospective study was performed to (1) characterize the clinical and histologic features of those with nonalcoholic fatty liver disease (NAFLD) and normal alanine aminotransferase (ALT) values, (2) compare the spectrum of NAFLD associated with normal versus elevated ALT levels, and (3) determine whether there were differences in the clinical or histologic spectrum of NAFLD between those with a low normal versus high normal ALT value. A total of 51 subjects with NAFLD and normal ALT were identified and compared with 50 consecutive subjects with NAFLD and elevated ALT. The major indications for liver biopsy in those with normal ALT were unexplained hepatomegaly (n = 21) and evaluation as a potential donor for living donor liver transplantation (n = 16). The 2 groups were comparable with respect to age, gender distribution, and ethnicity. Approximately 80% of cases in both groups had at least 1 feature of the metabolic syndrome, the major risk factor for NAFLD. The 2 groups were also comparable with respect to the grade of the individual histologic parameters of NAFLD. A total of 12 subjects with normal ALT levels had bridging fibrosis, whereas 6 had cirrhosis. Diabetes was the only factor independently associated with an increased risk of advanced fibrosis (bridging fibrosis or cirrhosis) by multivariate analysis (relative risk: 2.3, P <.01). The mean steatosis (1.6 vs. 2.16, P <.04) and perisinusoidal fibrosis scores (0.35 vs. 0.9, P <.049) were lower in those with low normal (<30 IU/L) ALT versus high normal ALT. However, the prevalence of advanced fibrosis was similar (5 of 15 vs. 13 of 36, respectively). In conclusion, (1) the entire histologic spectrum of NAFLD can be seen in individuals with normal ALT values, (2) the histologic spectrum in these individuals is not significantly different from those with elevated ALT levels, and (3) a low normal ALT value does not guarantee freedom from underlying steatohepatitis with advanced fibrosis.