Autoimmune Hepatitis

Question 1

Define autoimmune hepatitis and summarise its epidemiology

Answer 1

Definition: Chronic hepatitis of unknown aetiology,
characterised by autoimmune features, hyperglobulinaemia and the presence of circulating autoantibodies.

Epidemiology:

• Type 1: Occurs in ALL age groups (but mainly young women)
• Type 2: Generally occurs in girls and young women

Risk factors include:

• female gender
• genetic pre-disposition
• immune dysregulation
• measles virus

Question 2

Summarise the aetiology of autoimmune hepatitis

Answer 2

Aetiology:
- Genetic predisposition + environment agent (e.g. viruses or drugs) = hepatocyte expression of HLA antigens , which become focus of a principally T-cell mediated autoimmune attack.

• The raised titre of anti-nuclear antibodies (ANA), anti-smooth muscle antibodies (ASNA) and anti-liver/kidney microsomes (anti-KLM) are NOT thought to directly injure the liver.
• The chronic inflammatory changes are similar to those seen in chronic viral hepatitis with lymphoid infiltration of the portal tracts and hepatocyte necrosis, leading to fibrosis and, eventually cirrhosis

Question 3

What the two major forms autoimmune hepatitis?

Answer 3

• Type 1:
  o ANA
  o ASMA
  o Anti-actin antibodies (AAA)
  o Anti-soluble liver antigen (anti-SLA)
• Type 2:
  o Antibodies to liver/kidney microsomes (ALKM-1)
  o Antibodies to liver cytosol antigen (ALC-1)

Question 4

Describe the history/ presenting symptoms of autoimmune hepatitis

Answer 4

• Can be asymptomatic and discovered through abnormal LFTS
• Insidiously present with:
  o Malaise
  o Fatigue
  o Anorexia
  o Weight loss
  o Nausea
  o Jaundice
  o Amenorrhoea
  o Epistaxis

- Acute hepatitis (25%) presents with:
     o Fever
     o Anorexia
     o Jaundice
     o Nausea/ Vomiting/ Diarrhoea 
     o RUQ pain
     o Some may present with serum sickness (e.g. arthralgia, polyarthritis, maculopapular rash)

• Note: Check for personal or family history of other autoimmune diseases
• A full history is important to rule out other causes of hepatitis (e.g. viral, alcoholic)

Question 5

What are the signs of alcoholic hepatitis upon physical examination?

Answer 5

• Stigmata of chronic liver disease (e.g. spider naevi)
• Ascites, oedema and hepatic encephalopathy are late features
• Cushingoid features may be present even before the administration of steroids.

Question 6

What investigations are used to identify alcoholic hepatitis?

Answer 6

• Bloods:
  o LFTS (1st line investigation):
  • High: AST. ALT, GGT, ALP and Bilirubin
  • Low: Albumin (in severe disease)
  o Clotting:
  • High PT (in severe disease)
  o FBC:
  • Low Hb, platelets and WCC (if hypersplenism from portal hypertension)
  oHypergammaglobulinaemia:
  • Presence of ANA, ASMA anti Anti-LKM antibodies
• Liver Biopsy:
  o Needed to establish diagnosis and check whether hepatitis or cirrhosis
• US, CT or MRI of liver and abdomen:
  o Visualise structural lesions
• ERCP:
  o To rule out Primary sclerosing cholangitis (PSC)