Liver Function Test

Question 1

What are the classifications of liver disease

Answer 1

• Infection (Viral, bacterial, parasitic)
• Toxic/drug induced
• Autoimmune
• Biliary tract obstruction
• Vascular
• Metabolic
• Neoplastic

Question 2

Causes of acute hepatitis

Answer 2

• Poisoning (paracetamol)
• Infection (Hep A-C)
• Inadequate perfusion

Question 3

Outcome of acute hepatitis

Answer 3

• Resolution in majority of cases
• Progression to acute hepatic failure
• Progression to chronic hepatic damage

Question 4

Common causes of chronic liver disease

Answer 4

• Alcoholic fatty liver
• Chronic active hepatitis
• Primary biliary cirrhosis

Question 5

Unusual causes of chronic liver disease

Answer 5

• a-1 AT deficiency
• Haemochromatosis
• Wilson’s disease

Question 6

Define cholestasis

Answer 6

Failure to produce/excrete bile

Question 7

Result of cholestasis

Answer 7

Accumulation of conjugated bilirubin in the blood, leading to jaundice

Question 8

What does liver failure result in

Answer 8

• Inadequate synthesis of albumin, leading to oedema and ascites
• Inadequate synthesis of clotting factors, resulting in bruising
• Inability to eliminate bilirubin, causing jaundice
• Inability to eliminate nitrogenous waste (e.g. ammonia) giving rise to hepatic encephalopathy

Question 9

What do current liver function tests cover

Answer 9

• Albumin
• ALT (+ AST)
• ALP (+ gamma-GT)
• Bilirubin

Question 10

Why measure albumin

Answer 10

Synthetic function

Question 11

Why measure ALT

Answer 11

Aminotransferases for hepatocellular damage

Question 12

Why measure ALP

Answer 12

For biliary epithelial damage and obstruction

Question 13

Why measure bilirubin

Answer 13

For cholestasis

Question 14

Advantages of current liver function tests

Answer 14

• Cheap, widely available, interpretable

- Able to direct next subsequent investigation (e.g. imaging)

Question 15

Disadvantages of current liver function tests

Answer 15

• Does not assess liver function
• Lack of complete organ specificity
• Lack of disease specificity
• May be over-sensitive

Question 16

Where else is low albumin found

Answer 16

• Post-surgical/ITU patients due to redistribution
• Significant malnutrition
• Nephrotic syndrome

Question 17

When is ALP raised

Answer 17

• In liver disease due to increased synthesis

- In response to cholestasis

Question 18

When is gamma-GT raised

Answer 18

• Cholestasis

- Affected by ingestion of alcohol/drugs such as phenytoin

Question 19

Where else is ALP present

Answer 19

• Bone
• Gut
• Placenta

Question 20

Where else is gamma-GT present

Answer 20

• Bone
• Biliary tract
• Pancreas
• Kidney

Question 21

What happens to bilirubin once excreted in bile

Answer 21

• Attacked by bacteria in colon and excreted in faeces

- Small amounts reabsorbed and excreted in urine as urobilirubin

Question 22

What can cause cholestasis

Answer 22

• Failure by hepatocytes (intrahepatic cholestasis)

- Obstruction to bile flow (extra hepatic obstruction)

Question 23

What does an increased est ALT/ALP, normal ALT and increased ALP suggest

Answer 23

Cholestasis

Question 24

What does an increased est ALT/ALP and >10 fold increase in ALT and decrease in ALP suggest

Answer 24

Hepatocellular

Question 25

What else can cause changes in bilirubin

Answer 25

- Haemolysis | - Gilberts syndrome

Question 26

What else can cause changes in ALP

Answer 26

Physiological e.g. pregnancy, childhood

Question 27

What else can cause changes in ALT

Answer 27

Skeletal muscle disorders e.g. MI

Question 28

What else can cause changes in gamma-GT

Answer 28

- Alcohol | - Drugs

Question 29

When to perform caeruloplasmin/copper studies

Answer 29

Wilson's disease

Question 30

When to perform iron studies

Answer 30

Haemochromatosis

Question 31

When to perform autoantibodies

Answer 31

- Chronic active hepatitis | - PBC

Question 32

When to perform radiological intervention

Answer 32

- Obstruction | - Hepatomegaly

Question 33

What is intelligent LFTs (iLFTs)

Answer 33

- Combination of published diagnostic guidelines and expert opinion - Combination of biochemistry, haematology and serology in conjunction with liver ultrasound

Question 34

Who is considered for iLFTs

Answer 34

Patients with abnormal LFT's in whom the cause in unclear (patients with frank jaundice excluded)

Question 35

First stage of iLFT

Answer 35

- Patient specific data (age, gender, BMI, alcohol intake etc) - LFT and FBC performed (ALT, albumin, bilirubin, alk phos, gamma GT and platelets)

Question 36

Second stage of iLFT

Answer 36

- If any of previous test abnormal - Aetiology screen (hepatitis serology, liver immunology, ferritin - Fibrosis staging