Autoimmune hepatitis

Types

• Type 1 - ANA and Anti-SMA positive
• Type 2 - Anti LMK 1 positive

Etiology

• occurs after unknown trigger to T-cell mediated immune response by
  • molecular mimicry
  • toxin
  • drugs
  • infections
• DR3, DR4, DR7 confer susceptibility to AIH
• mediated by CD4+ and CD8+ Th cells
• AIRE gene is implicated

pathology

• Interface hepatitis
  • inflitration of hepatic lobules by lymphocytes and plasma cells
• Bridging necrosis
  • variable fibrosis, necrosis and collapse spanning between portal triads or portal traids and central vein
• piecemeal necrosis
  • moderate ot severe piece meal necrosis of hepatacytes extending outward from limiting plate
• Cirrhosis ∓

Clincal features

• variable
• 25-30% - mimic viral hepatitis
• fatigue, malaise, anorexia, behavioral changes, amenorrhea
• Extrahepatic manifestations
  • arthritis, vasculitis, nephritis, throiditis,
• coomb's positive anemia and rash
• spider telengectasia and palmar erythema

Lab findings

• AST/ALT in ranges of 100-300 (can be as high as 1000)
• S. bili 2-10
• γ-GT elevated
• PT/INR prolonged
• hypoalbuminemia
• hypergammaglobulinemia
• ANA/AntiSMA/Anti LKM1/Anti LC2
• titres as low as 1:40 are significant
• overlap syndrome
  • overlap between primary sclerosing cholangitis and autoimmune immune hepatitis

Treatment

• Prednisolone ∓ Azothioprine
• Prednisolone
  • 1-2 mg/kg/24 hrs
  • continued till aminotransferases return to normal values
  • Budesonide 9mg/day can be used as a alternative
• Azothioprine
  • 1.5-2 mg/kg/24 hr (max 100 mg/day)
  • wait for 2 weeks to look for steroid responsiveness before starting azothioprine
• monitor LFT every 2 to 3 months
• 2nd line drugs
  • cyclophosphomide
  • tacrolimus
  • mycophenolate mofitil
• UDCA
  • 10 mg/kg/dose BD

prognosis

• able to wean 25-40%
• type 1 autoimmune hepatitis has better prognosis than type 2
• non adherence is a common factor for resistance
• Liver transplant can be done
  • 30% will recur