Autoimmune hepatitis (AIH) is a rare form of chronic hepatitis that predominantly affects women. Although the etiology is unclear, it is commonly associated with other autoimmune conditions (e.g., thyroid disease, type 1 diabetes mellitus, celiac disease). The clinical presentation ranges from asymptomatic transaminitis to acute liver failure. Diagnosis is established based on the detection of autoantibodies (e.g., antinuclear antibodies, anti-smooth muscle antibodies) and the histologic findings of interface hepatitis on liver biopsy. Treatment consists of immunosuppressive medications such as prednisone and azathioprine. The prognosis is favorable with treatment; without treatment, patients may develop cirrhosis and liver failure.
- Prevalence: 0.1–2/100,000 white adults in the US, even less so in other ethnicities 
- Bimodal distribution: 10–20 years and 40–60 years 
- Sex: ♀ > ♂
Epidemiological data refers to the US, unless otherwise specified.
- Consider AIH in patients with unexplained liver disease.
- Rule out other causes of hepatitis; see “Differential diagnoses.”
- Establish the diagnosis of AIH with laboratory studies and liver histology.
- Consider utilizing the Autoimmune Hepatitis Diagnosis calculator to facilitate the diagnosis. 
- Consult hepatology for guidance on further diagnostic testing.
Initial studies 
Laboratory tests 
- Liver chemistries: ↑↑↑ ALT and ↑↑ AST; , ↑ GGT, normal or ↑ ALP, and ↑ bilirubin
- Serum antibodies
- SPEP: hypergammaglobulinemia (↑ IgG)
- CBC: normochromic anemia, thrombocytopenia, mild leukopenia
- Inflammatory markers: ↑ ESR
Liver biopsy 
- Perform following the detection of AIH antibodies to confirm the diagnosis.
- Histological findings:
Additional evaluation 
- Obtain further serum antibodies to clarify diagnosis if initial antibody testing is negative.
- Screen all patients for concomitant celiac disease (with anti-tTG) and thyroid disease (with TSH).
- Assess for other common comorbidities (e.g., rheumatoid arthritis, diabetes mellitus, inflammatory bowel disease) based on clinical suspicion.
General principles 
- Initiate if necessary.
- Refer patients to a hepatologist for management.
Immunosuppression is the mainstay of treatment.
- Provide and pretreatment counseling.
- Liver transplantation is indicated in patients with decompensated liver cirrhosis.
- Indication: active disease (i.e., elevated transaminases, elevated IgG, and/or histological disease)
- Goals of treatment
- Maintenance: glucocorticoid discontinuation after gradual tapering; continue AZA.
- Treatment withdrawal
- 10-year survival rate with treatment: > 90% 
- Type 2 AIH is associated with more severe disease, a worse response to corticosteroids, and more frequent relapses.
- Increased risk of liver cirrhosis if left untreated