Liver Function Test

Question 1

List the different enzymes/proteins which are checked for in liver function tests

Answer 1

bilirubin
albumin
alanine aminotransferase (ALT) and/or
aspartate aminotransferase (AST) 
Alkaline phosphatase
gamma glutamyl transferase (γ-GT) 
total protein

Question 2

What is usually the cause of unconjugated/conjugated hyperbilirubinemia ?

Answer 2

Elevated levels of unconjugated: prehaptic and hepatic (alcohol, hepatitis)
Elevated levels of conjugated: post hepatic

Question 3

what type of bilirubin does Gilberts’ syndrome increase more?

Answer 3

unconjugated

Question 4

what are aspartate (AST) and alanine aminotransferase (ALT) markers of?

Answer 4

Markers of hepato-cellular injury

Question 5

Describe ALT (alanine amino transferase) - location, plasma half life and what an increase in it shows

Answer 5

Cytosolic enzyme
Plasma half life of 18 hours
High ALT = liver damage (hepatitis, infection, cirrhosis, liver cancer, or other liver diseases) ???

Question 6

Describe AST (aspartate amino transferase) - location, plasma half life and what an increase in it shows

Answer 6

Present in cytosolic and mitochondrial isoenzymes
Present in liver, cardiac and skeletal muscle, kidneys, brain/CNS, (pancreas, lungs, leukocytes and red cells)

Plasma half-life 48 hours
high levels = acute hepatitis

Question 7

Out of AST and ALT which ones is more specific to the liver?

Answer 7

ALT

Question 8

What does an ALT/AST ratio of more than 2:1 show?

Answer 8

suggestive of alcoholic liver disease

Question 9

What is glutamyl transferase responsible for? Where is it found? IS it specific to liver disease?

Answer 9

Responsible for the transfer of glutamyl groups from gamma-glutamyl peptides to other peptides or aminoacids

Present throughout the liver and hepatobiliary tree. Also found in other organs (heart, kidneys, lungs, pancreas and seminal vesicles) but plasma activity is mostly related to the liver isoenzyme.

Poor specificity for liver disease

Question 10

How are the levels of GGT and ALP linked?

Answer 10

If there is raised Alkaline phosphatase (ALP), it important to review the level of GGT.

If GGT is raised but ALP is not = alcohol has caused damage
If GGT + ALP are raised = problem with bile ducts and liver ??

Question 11

What is ALP important for? Where is it mostly found? What do high levels of ALP indicate?

Answer 11

ALP is an enzyme which is important for breaking down proteins
It is particularly concentrated in the liver, bile duct and bone tissues.

Levels rise in bile duct obstruction

Question 12

In what type of people is ALP found to be raised without liver/bone damage ?

Answer 12

Pregnant women

Question 13

Why is measure prothrombin time important for LFT and what is it?

Answer 13

The prothrombin time (PT) measures the rate of conversion of prothrombin to thrombin and thus reflects a vital synthetic function of the liver

Question 14

What are abnormal ranges traditionally defined as ?

Answer 14

Abnormal ranges have been traditionally defined from the upper 2.5% of results of healthy volunteers

Question 15

What symptoms do those with abnormal LFT results present with?

Answer 15

◼ weight loss
◼ anorexia
◼ vomiting
◼ pain
◼ myalgia (muscle pain)
◼ jaundice
◼ pruritus (itchy skin - due to high bilirubin)
◼ change in colour of urine and/or stool

Question 16

What are some stigmata (physical characteristics) seen as a result of chronic liver disease/portal hypertension?

Answer 16

◼ spider nevi (cluster of vessels which is web-like, with a central spot and radiating vessels)
◼ palmar erythema (a reddening of the skin on the palmar aspect of the hands)
◼ caput medusae (appearance of distended and engorged superficial epigastric veins)

Ascites
Pleural effusion
Ankle oedema

Hepatomegaly, splenomegaly,