Autoimmune Hepatitis

Autoimmune hepatitis is a chronic immune mediated hepatitis with interface inflammation, hypergammaglobulinaemia and autoantibodies.

• Prevalence is about 10 to 20 per 100,000, female predominance 3:1, with peaks in childhood and age 40 to 60.
• Type 1 (ANA, anti smooth muscle, anti actin) is the commonest. Type 2 (anti LKM1, anti LC1) affects children and young adults with more aggressive disease.
• Associated HLA DR3 and DR4. Triggers include drugs (nitrofurantoin, minocycline, statins, infliximab) and viral infection.
• Associations: thyroiditis, coeliac disease, type 1 diabetes, ulcerative colitis, Sjögren.
• Variants: overlap with primary biliary cholangitis or sclerosing cholangitis, and acute severe or fulminant presentation.

• Insidious fatigue, arthralgia, amenorrhoea, jaundice, or acute hepatitis in a third.
• Asymptomatic with raised transaminases or cirrhosis at presentation (25% of adults).
• Acute severe disease: jaundice, coagulopathy, encephalopathy.
• Extrahepatic autoimmune features.

• ALT and AST raised, with IgG above the upper limit, ANA or SMA at 1:40 or more, or anti LKM1.
• Biopsy: interface hepatitis, plasma cell infiltrate, rosettes, emperipolesis. Required for diagnosis.
• Simplified diagnostic score of 7 or more is definite disease.
• Exclude viral hepatitis (A, B, C, E), Wilson disease (young patients), drug induced autoimmune like injury, haemochromatosis, MASLD, alpha 1 antitrypsin.
• Check anti mitochondrial antibodies, MRCP if cholestatic features, TPMT before azathioprine.

• Induction: prednisolone 0.5 to 1 mg/kg (30 to 60 mg) daily, reduced weekly to 10 mg over 4 to 8 weeks. Add azathioprine 50 mg then 1 to 2 mg/kg daily after bilirubin falls below 6 mg/dL.
• Budesonide 9 mg daily with azathioprine is an option in noncirrhotic disease.
• Maintenance: azathioprine 1 to 2 mg/kg daily, with the lowest effective steroid dose or none.
• Remission is normal transaminases and IgG. Continue treatment for at least 2 to 3 years after remission, and withdrawal is attempted cautiously with a relapse rate of 50 to 80%.
• Steroid intolerance or azathioprine failure: mycophenolate mofetil 1 to 1.5 g twice daily, then tacrolimus, rituximab, infliximab.
• Fulminant disease: methylprednisolone 1 mg/kg IV with early transplant listing.
• Bone protection (calcium, vitamin D, bisphosphonate), vaccination, HCC surveillance in cirrhosis.
• Pregnancy is safe in remission. Continue azathioprine.