Autoimmune Hepatitis

Background/Epidemiology

  • Autoimmune hepatitis is a chronic inflammatory condition affecting the liver which can eventually lead to cirrhosis/liver failure.
  • There were formerly two main types of autoimmune hepatitis (NB not commonly used any longer)
    • Type 1- associated with ASMA (Anti-smooth muscle antibodies) or ANA (antinuclear antibodies)
    • Type 2- associated with anti-LKM1 or anti-liver cytosolic-1 (anti-LC-1) antibodies (usually more common in younger patients and typically more difficult to treat)
  • Prevalence of around 10-17/100,000; more common in women (3:1) (associated with other autoimmune conditions)

Aetiology/Pathophysiology

  • Possible triggers include viral infections (HepA and EBV), in genetically susceptible individuals (HLA-DR3 and DR4)
  • There are usually high levels of circulating ANA or ASMA.  Damage to the liver is caused by activation of the immune system by binding of these antibodies, presentation to antigen-presenting cells and subsequent activation and recruitment of T cells and release of inflammatory mediators.
    • Typically, in the acute phase, this appears as lymphoplasmacytic infiltrate on biopsy
      • With chronic disease, there may be evidence of fibrosis/cirrhosis (NB the patients may present with this (see below))

Presentation

  • Up to a third present with cirrhosis and features of chronic liver disease and up to a quarter will be completely asymptomatic
  • Onset is usually insidious but can be acute in up to a quarter (may resemble viral hepatitis)
  • Fatigue, arthralgia, anorexia, nausea etc
  • Bruising, rashes (acne)
  • Pruritus is often more common than frank jaundice (if present is rarely severe)
    • Other signs of chronic liver disease e.g. spider naevi, palmar erythema, hepatomegaly/splenomegaly, oedema etc can be present.
  • NB Features of associated autoimmune conditions may also be present e.g. Hashimoto’s thyroiditis, thyrotoxicosis, ulcerative colitisnephrotic syndrome, rheumatoid arthritis

Investigations

  • FBC may show a mild leukopenia, normochromic/normocytic or microcytic anaemia, thrombocytopenia
    • May also show a raised ESR/PV
  • LFTs usually shows elevated AST/ALT (often >3-fold); Alk Phos may be slightly elevated BUT more than twice normal is suggestive of another diagnosis (associated or not)
  • Serum IgG is usually markedly high
  • Autoantibodies should be investigated (Anti-nuclear and anti-smooth muscle)
    • Liver cytoplasm and liver kidney microsomal antibodies may also be investigated (previously type II)
  • Liver biopsy
    • Features include a lymphoplasmacytic interface hepatitis, lobular hepatitis and centrolobular necrosis

Management

  • Who to treat
    • Severe disease (one or more of: AST>5 x normal; serum IgG >2 x normal; liver biopsy showing confluent necrosis)
    • Symptomatic disease
    • Young patients
      • There is no need to treat asymptomatic older patients
  • Treatment
    • Initially high dose (40mg) prednisolone, with a reducing dose as LFTs improve.
      • Azathioprine is added to lower the maintenance dose of steroid treatment (in some cases, azathioprine can be used alone)
  • Transplant
    • Around 10-20% of patients with AIH will require a transplant during their lifetime (NB recurrence may occur)

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