Autoimmune Hepatitis

Question 1

What is autoimmune hepatitis?

Answer 1

Autoimmune hepatitis = chronic inflammatory disease of the liver, characterised by autoimmune features, hyperglobinaemia and presence of circulating auto-antibodies

Supported by histology and favourable response to immunosuppression
Diagnosis of exclusion?

Question 2

What is the aetiology of autoimmune hepatitis?

Answer 2

• 4 main factors
Genetic predisposition
HLA genes of MHC on short arm of C6

Environmental trigger
Auto-antigens
Immunoregulatory dysfunction

2 hit hypothesis
First hit = genetically predisposed individual
Second hit = environmental agent, e.g. viruses or drugs

Leads to hepatocyte expression of HLA antigens which are targeted by a T-cell mediated attack

2 major forms
Type 1 (Classic) - ANA, anti-SM Abs (ASMA), anti-actin Abs (AAA), m 

Type 2 - Anti-liver/kidney microsomes Abs

Question 3

What are the risk factors for autoimmune hepatitis?

Answer 3

Female 
Genetics
Immune dysregulation
35% have other autoimmune disease
Viral infection (measles, CMV, EBV, hep A/C/D)

Question 4

What is the epidemiology for autoimmune hepatitis?

Answer 4

More common in females (80% in type 1 and 90% in type 2)
Higher prevalence with northern-European ancestry
Type 1 is the most common form

Question 5

What are the symptoms of autoimmune hepatitis?

Answer 5

Insidious onset (75%):
Fatigue and malaise
Anorexia
Weight loss
Nausea
Amenorrhoea

Acute hepatitis (25%):
Anorexia
Abdominal discomfort/RUQ pain
Serum sickness - Maculopapular rash, Arthralgia
Nausea and vomiting

Question 6

What are the signs of autoimmune hepatitis?

Answer 6

Hepatomegaly

Jaundice

Acute onset - Fever

Stigmata of chronic liver disease - Spider naevi/angiomata

Late features - Ascites, Oedema, Encephalopathy

Question 7

What are the investigations for autoimmune hepatitis?

Answer 7

Bloods
LFTs: very elevated AST/ALT/GGT, elevated AlkPhos/bilirubin, low albumin
Clotting: prolonged PT
FBC: mild anaemia, thrombocytopenia
Immunology: hypergabbaglobulinaemia, ANA+, ASMA+, anti-LKMA+

Liver biopsy - Histology showing interface hepatitis or cirrhosis

Other investigations
Bloods - (Rule out other causes)
Viral serology = hep B/C
Caeruloplasmin and urinary copper = Wilsons
Ferritin and transferrin sats = haemochromatosis
A-1-antitrypsin = A1AT deficiency
Antimitochondrial Abs = PSC

Imaging: US/CT/MRI - Visualise structural lesions

ERCP - Rule out Primary sclerosing cholangitis