OBJECTIVES: Autoantibodies may exist in serum of patients with nonalcoholic fatty liver disease (NAFLD) although their prevalence and clinical significance is uncertain. We aimed at examining the prevalence of autoantibodies and autoimmune hepatitis among patients with NAFLD. METHODS: Prevalence of antinuclear antibodies (ANA), anti-smooth muscle antibodies (anti-SMA), and autoimmune hepatitis (AIH) based on the International AIH Group were determined in 225 patients with liver biopsy-proven NAFLD. RESULTS: Fifty-one patients [23% (95% CI 17.3-28.2%)] had autoantibodies in serum which is significantly higher than the prevalence in the general population. ANA were present in 46 patients (20%), SMA in 6 (3%), and both antibodies in one patient. Positive autoantibodies were associated with higher fibrosis stage (p = 0.03), higher inflammatory grade (p = 0.02), and higher levels of gammaglobulin (p = 0.01). Prior to liver biopsy, 45 of the 51 (88%) patients with positive autoantibodies fulfilled diagnostic criteria for 'probable' or 'definite' AIH. After liver biopsy, however, only four patients fulfilled diagnostic criteria. CONCLUSIONS: Routinely measured autoantibodies are present in one quarter of patients with NAFLD and are associated with more severe histological damage. Liver biopsy is required to rule out AIH in most NAFLD patients with positive autoantibodies.
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