A 28-year-old woman presents with jaundice, fatigue, arthralgias, and amenorrhea. Serum ALT is 380 U/L, AST 320 U/L, total bilirubin 4.2 mg/dL, ANA 1:320 positive, anti-smooth muscle antibody (ASMA) positive 1:640, serum IgG 28 g/L. Liver biopsy shows interface hepatitis with plasma cell infiltration. What is the diagnosis and cornerstone of treatment?

• A Autoimmune hepatitis; start prednisone with or without azathioprine ✓
• B Primary biliary cholangitis; start ursodeoxycholic acid
• C Viral hepatitis B; start tenofovir
• D Drug-induced liver injury; identify and stop offending drug

Explanation

Autoimmune hepatitis (AIH) is characterized by elevated transaminases, positive autoantibodies (ANA, ASMA), markedly elevated IgG, and interface hepatitis on biopsy. The simplified Autoimmune Hepatitis Score (Simplified AIH Score) with these features strongly suggests AIH. Prednisone alone or in combination with azathioprine achieves remission in approximately 65–80% of patients, with normalization of transaminases and IgG. Untreated AIH can progress to cirrhosis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.