Liver Function Tests

Question 1

Components

Answer 1

• FBC, U&Es, LFTs and coagulation screen
• Hepatitis viral serology
• Autoantibodies (anti-mitochondrial antibodies - PBC, anti-smooth muscle antibodies - autoimmune hepatitis)
• Iron studies (haemochromatosis)
• Serum copper and caeruloplasmin (Wilsons disease <40)
• Alpha-1 antitrypsin (for deficiency)
• Alpha-feto protein (for hepatocellular carcinoma)
• Immunoglobulins (IgG in autoimmune hepatitis and IgM in PBC)
• Paracetamol level
• Liver USS

Question 2

Pattern in pre-hepatic jaundice

Answer 2

• Isolated raised bilirubin
• Anaemia (normo or macrocytic)
• Raised LDH
• Decreased haptoglobin
• Urobilinogen increased
• Reticulocytosis and damaged RBCs on blood film
• Positive Coomb’s test indicates immune cause

Question 3

Pattern in post-hepatic (obstructive) jaundice

Answer 3

• Raised bilirubin
• Raise ALP
• Raised GGT

Question 4

Causes of pre-hepatic jaundice

Answer 4

• Haemolytic anaemia

- Gilbert’s disease (inherited defect in bilirubin metabolism)

Question 5

Causes of post-hepatic (obstructive) jaundice

Answer 5

• PBC
• PSC
• Drugs
• Gallstones
• Malignancy (pancreatic carcinoma, lymph nodes, cholangiocarcinoma)

Question 6

Pattern in liver disease

Answer 6

• Raised bilirubin
• Prolonged PT
• Decreased albumin

Question 7

Alcoholism

Answer 7

• Raised GGT
• Raised MCV
• Thrombocytopaenia

Question 8

What is bilirubin?

Answer 8

• Breakdown product of haemoglobin

Question 9

What is Aspartate Aminotransferase (AST)/Alanine Aminotransferase (ALT)?

Answer 9

• Enzymes present in hepatocytes which leak out in the event of damage.
• ALT is more specific for the liver.
• AST is also found in heart and skeletal muscle.

Question 10

What is Alkaline Phosphatase (ALP)?

Answer 10

• Found in the canicular and sinusoidal membranse of the liver.
• Raised in cholestasis (impaired bile flow) and biliary obstruction (malignancy, infection).
• Also in placenta and one so levels raised in Paget’s disease, pregnancy and with bony metastases.

Question 11

What is Gamma GT?

Answer 11

• Liver enzyme induced by alcohol and by certain enzyme inducing drugs (e.g. phenytoin).
• Also released in hepatocellular damage.

Question 12

What is albumin?

Answer 12

• Produced by the liver so a good indicator of synthetic function.
• Hypoalbuminaemia also caused by hypercatabolic states (sepsis, chronic inflammation) and where there are excessive losses (renal-nephrotic syndrome, GI-protein losing enteropathy).

Question 13

What is total protein?

Answer 13

• If significantly raised and albumin low or normal consider the presence of paraprotein.