AI Hepatitis

Question 1

Epidemiology of AI hepatitis

Answer 1

Young and middle aged females

Northern European ancestry (HLA DR3 and DR4)

Question 2

3 types of AI hepatitis

Answer 2

Type 1: bimodal age distribution, anti-smooth muscle Ab (ASMA; in 80%), ANA (in 10%), hypergammaglobulinaemia (IgG), HLA DR3 and DR4
Type 2: young females, more likely to progress to cirrhosis, anti-liver/kidney microsomal type 1 (LKM1) Ab
Type 3: adults, clinically identical to type 1, Ab against soluble liver Ag/liver-pancreas Ag (SLA/LP)

Question 3

Diagnosis of AI hepatitis

Answer 3

On basis of exclusion; huge overlap with PBC and PSC

Question 4

Clinical presentation of AI hepatitis

Answer 4

Can be asymptomatic
Signs of acute hepatitis
Signs of AI disease
Signs of chronic liver disease
Amenorrhoea

Question 5

Signs of AI disease (e.g. AIH, RA, SLE)

Answer 5

Urticarial rash
Polyarthritis
Pleuritis
Pulmonary infiltration
Glomerulonephritis

Question 6

Main DDx of hepatitis

Answer 6

AIH, PBC, PSC
Alcoholic hepatitis
Viral hepatitis
NAFLD
Drug-induced hepatitis
Haemachromatosis, Wilson's, a1-antitrypsin deficiency
SLE
Granulomatous hepatitis (e.g. TB, fungal, etc)

Question 7

Investigations for AI hepatitis

Answer 7

FBE: anaemia, decreased WCC, decreased platelets (due to hypersplenism, decreased thrombopoietin)
Serum globulin: hypergammaglobulinaemia (IgG)
Serum albumin: hypoalbuminaemia
LFTs: mild to moderate increase in aminotransferases, GGT, ALP, bilirubin
Viral serology
Abdo U/S
AutoAbs: ANA, ASMA, LKM1
Liver biopsy: evaluate severity and treatment
Others for DDx (e.g. iron, a1-antitrypsin, aFP)

Question 8

Management of AI hepatitis

Answer 8

Corticosteroids (long term prednisolone)
Azathioprine
Liver transplant if decompensated cirrhosis or failure to respond to medication

Question 9

Azathioprine mechanism of action

Answer 9

Decreased synthesis of DNA

Question 10

Azathioprine contraindication

Answer 10

Thiopurine methyltransferase (TPMT) deficiency