Autoimmune Hepatitis

Question 1

Definition

Answer 1

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

Question 2

Aetiology

Answer 2

· In a genetically predisposed individual, and environmental agent (e.g. viruses or drugs) may lead to hepatocyte expression of HLA antigens, which then become the focus of a principally T-cell-mediated autoimmune attack

· The raised titre of anti-nuclear antibodies (ANA), anti-smooth muscle antibodies (ASMA) and anti-liver/kidney microsomes (anti-LKM) 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

Two types

Answer 3

· TWO major forms of autoimmune hepatitis:

o Type 1 (Classic)
· ANA
· ASMA
· Anti-actin antibodies (AAA)
· Anti-soluble liver antigen (anti-SLA)

o Type 2
· Antibodies to liver/kidney microsomes (ALKM-1)
· Antibodies to liver cytosol antigen (ALC-1)

Question 4

Epidemiology

Answer 4

· Type 1: occurs in ALL age groups (but mainly young women)

· Type 2: generally occurs in girls and young women

Question 5

Presenting symptoms

Answer 5

· May be asymptomatic and discovered incidentally through abnormal LFT

· 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 6

Signs on physical examination

Answer 6

· 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 7

Investigations (bloods)

Answer 7

o LFTs:
· 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)

o Hypergammaglobulinaemia
· Presence of ANA, ASMA and Anti-LKM antibodies

Question 8

Investigations (causes)

Answer 8

· To rule out other causes of liver disease:

o Viral serology
o Urinary copper/caeruloplasmin
o Ferritin and transferrin saturation
o a1 antitrypsin
o Anti-mitochondrial antibodies (PBC - primary biliary cholangitis)

Question 9

Investigations (other)

Answer 9

· 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 PSC (primary sclerosing cholangitis)