Liver Failure

Question 1

Why can albumin levels be normal in acute liver injury?

Answer 1

Has half life of 20 days

Question 2

Which is affected more by liver disease: INR, or APTT?

Answer 2

INR

Question 3

Why can INR and APTT be increased in cholestasis?

Answer 3

Poor absorption of fat soluble vitamins > vitamin K deficiency

Question 4

What are common causes of acute liver injury?

Answer 4

Drug poisoning
- Paracetamol
Acute viral hepatitis
- HVA, HVB, HVC
- Less common: EBV, others
Idiosyncratic acute drug reactions
Ischaemia
- Circulatory shock
- Acute severe heart failure

Question 5

What are the common causes of acute hepatitis?

Answer 5

Acute viral hepatitis
Drug related
Ischaemic hepatitis
Autoimmune
Acute Budd Chiari
Wilson's disease
Idiopathic

Question 6

What is the criteria for transfer to a liver transplant unit?

Answer 6

INR >1.5 and rising
Any encephalopathy
Poor prognosis

Question 7

Can paracetamol poisoning occur at recommended therapeutic doses?

Answer 7

Yes

Question 8

In whom should the daily dose of paracetamol be decreased, to avoid poisoning?

Answer 8

Fasting - starvation depletes glutathione
Heavy alcohol users
Taking medications that induce cytochrome P450

Question 9

What is the liver enzyme pattern in paracetamol poisoning?

Answer 9

Large rise in AST and ALT

Question 10

What is the role of biopsy in acute liver failure?

Answer 10

Quantify extent of liver injury
Establish aetiology
Guide to treatment

Question 11

What is the toxic dose of paracetamol?

Answer 11

200 mg/kg or 10 g - whichever is less

Question 12

What is the antidote for paracetamol poisoning?

Answer 12

N-acetylcysteine (NAC)

Question 13

What is the effectiveness of NAC in paracetamol poisoning?

Answer 13

100% effective if given within 8 hours of ingestion, regardless of dose ingested

Question 14

How is paracetamol metabolised?

Answer 14

95% conjugated to glucuronide > excreted in bile

5% undergoes P450 metabolism > NAPQI = toxic metabolite conjugated to glutathione > non-toxic

Question 15

What happens in paracetamol overdose?

Answer 15

Both arms of hepatic metabolism fail

Glutathione depleted > NAPQI builds up > hepatotoxicity

Question 16

How does NAC modify metabolism in paracetamol overdose?

Answer 16

Glutathione donor > reduced production of NAPQI

Question 17

What is the general management of paracetamol toxicity?

Answer 17

Prevention of absorption
- Activated charcoal within 60 min of ingestion
Symptomatic care
- Anti-emetics
Risk assessment
- Dose based/plasma paracetamol concentration
Specific care
- NAC

Question 18

What is the recommended staggered ingestion of paracetamol?

Answer 18

24 hours: 200 mg/kg or 10g - whichever less
48 hours: 150 mg/kg or 6 g/day - whichever less
More than 48 hours - 100 mg/kg or 4 g/day - whichever less

Question 19

What is the test for Wilson’s disease?

Answer 19

Caeruloplasmin

Question 20

What are the complications of chronic liver failure?

Answer 20

Hepatocellular cancer
Variceal bleeding
Ascites