Autoimmune chronic hepatitis
A chronic hepatitis of unknown aetiology characterised by circulating autoantibodies and inflammatory changes on liver histology.
Most common cause of chronic active hepatitis in developed countries.
10–30 and 40–60 years.
F > M (6:1)
No autoimmune mechanism has yet been proven, although high titres of autoantibodies are characteristic. Patients may have features that overlap with primary biliary cirrhosis and primary sclerosing cholangitis. Autoimmune chronic hepatitis is also commonly associated with other autoimmune disorders e.g. haemolytic anaemia, idiopathic thrombocytopenic purpura, type I diabetes mellitus, thyroiditis and ulcerative colitis (more often associated with primary sclerosing cholangitis).
The illness may be asymptomatic with elevated liver enzymes. Patients may have an acute hepatitis or complications of cirrhosis such as portal hypertension (e.g. bleeding oesophageal varices or hepatic encephalopathy).
Diagnosis of chronic active hepatitis is made by liver biopsy, there is often a normochromic anaemia, raised bilirubin, moderately raised transaminases, alkaline phosphatase and γ globulin levels. Autoantibodies that may be detected include anti-smooth muscle antibodies, anti-nuclear antibodies, anti-mitochondrial antibodies, anti-microsomal antibodies or anti-liver cystosol anti-bodies.
The condition may respond to immunosuppressant drugs, such as corticosteroids and azathioprine. In patients who develop end stage liver disease despite medical treatment liver transplantation may be considered although hepatitis may recur in the transplanted organ.
Drug treatment may be withdrawn after 2 years of remission, but relapse is common (60–80%). The risk of hepatocellular carcinoma is low, in contrast to chronic active hepatitis due to viral causes.