A case of rapid-onset antimitochondrial antibody-positive autoimmune hepatitis possibly triggered by a urinary tract infection

A 54-year-old woman suffered acute hepatitis after she acquired cystitis. Laboratory results on admission showed: AST 925, ALT 1171, ALP 623, γ-GTP127 IU/l, T-Bil 5.0 mg/dl, antinuclear antibodies negative, smooth muscle antibodies 80, antimitochondrial antibodies (AMA) 80, antimitochondrial M2 antibody (AMA-M2) 117 index, IgG 2210 mg/dl. She also had HLA-DR4 and HLA-DR8. Histological study of a liver biopsy specimen suggested that she had autoimmune hepatitis rather than primary biliary cirrhosis. When prednisolone was administered, her liver function immediately improved and AMA and AMA-M2 levels fell to 20 and 52 respectively. However when cystitis recurred 4 months later, her liver function worsened. Laboratory findings showed AST 174, ALT 183 IU/l. Upon increasing the dosage of prednisolone, her liver function improved again. After the recurrence of hepatitis, AMA and AMA-M2 levels increased to 320 and 149 respectively. We speculate that the urinary tract infection triggered an autoimmune response and her genetic predisposition also played a crucial role in the process.