Jaundice and LFTs

Question 1

What is jaundice?

Answer 1

A clinical manifestation of raised bilirubin causing yellowing of the skin and sclera

Question 2

What is bilirubin?

Answer 2

A breakdown product of the haem chain of Hb

Question 3

Why does bilirubin need to be conjugated? Where does this happen?

Answer 3

Conjugation happens in the liver

Unconjugated bilirubin is not water soluble and needs to be transported to by attachment to albumin

Conjugated bilirubin is water soluble

Question 4

After conjugation in the liver, what happens to the bilirubin?

Answer 4

3 options

• Excreted by the kidney in urine
• Excreted by the gut in faeces
• Enters bile

Question 5

What are the 3 main types of jaundice?

Answer 5

• Pre-hepatic
• Hepatic
• Post-hepatic

Question 6

Explain the pathophysiology of pre-hepatic jaundice

Answer 6

Jaundice due to increase degredation of Haemoglobin

The livers ability to conjugate is fine but the liver is overwhelmed by the increased demand of bilirubin

Question 7

Will the raised bilirubin in pre-heptic jaundice be conjugated or unconjugated?

Answer 7

Unconjugated

As the liver cannot conjugate all the increased Hb breakdown

Question 8

What common things cause pre-hepatic jaundice?

Answer 8

Haemoglobinopathies

• Sickle cell anaemia
• Thalassaemia
• Spherocytosis

Damage to RBC

• Haemolysis

Question 9

Explain the pathophysiology of hepatic jaundice

Answer 9

Jaundice due to damaged hepatocytes which means the livers ability to conjugate is reduced

Question 10

Will the raised bilirubin in hepatic jaundice be conjugated or unconjugated?

Answer 10

A mixure of both

The parts that aren’t damaged can conjugate whilst the the damaged hepatocytes cannot conjugate

Question 11

What kind of things can cause hepatic jaundice?

Answer 11

Anything that causes cirrhosis

• Infection
• Drugs
• Autoimmune
• Alcohol
• Wilson’s Disease
• Fatty Liver Disease
• Deposition disorders

Question 12

What is post hepatic jaundice?

Answer 12

Jaundice due to an obstruction of the extretion pathway of bilirubin from the liver

Question 13

Will the raised bilirubin in post-hepatic jaundice be conjugated or uncongugated?

Answer 13

Conjugated as there’s nothing wrong with the liver’s ability to conjugate

Question 14

What features would you see in the urine and faeces of someone with post-hepatic jaundice and why?

Answer 14

Dark urine and Light stools

Conjugated bilirubin is water soluble therefore more will be excreted by the kidneys and lost as urine and less in excreted by the gut and lost as faeces

Bilirubin is pigmented therefore the pigment causes the colour changes

Question 15

Give some of the common causes of post-hepatic jaundice

Answer 15

• Gallstones
• Biliary stricture (narrowing)
• Pathology in the head of the pancreas

Question 16

Why can intraheptic pathology cause post-hepatic jaundice?

Answer 16

Pathology such as oedema, fibrosis and malignant growths can compress the intrahepatic bile ducts

Question 17

What is albumin and why is it tested to test liver function?

Answer 17

Albumin is the major serum protein that is produced in the liver

Reduced liver function = reduced albumin

Question 18

Aside from reduced liver function, what kind of things could cause low serum albumin?

Answer 18

• inadequate protein intake
• increased loss via the kidneys
• physiologically less during pregnancy

Question 19

Which hepatic enzymes can be tested in liver function tests?

Answer 19

ALT Alanine Transaminase

AST Aspartate Transaminase

Both would be raised in hepatocyte damage

Question 20

Which of ALT and AST is more specific to the liver and why?

Answer 20

ALT

AST is also found in cardiac/ skeletal muscle and RBC

Question 21

How do the levels of ALT and AST vary in acute liver damage and cirrhosis/ alcoholic hepatitis?

Answer 21

Acute liver damage: ALT > AST

Cirrhosis/ Alcoholic Hepatitis: AST ? ALT

Question 22

The levels of which enzyme will go up in cholestatis?

Answer 22

ALP alkaline phosphatase

Found in cells that line the bile ducts

Question 23

Aside from the liver, whereelse can ALP be found? Which test would you do to test that ALP is specifically from the liver?

Answer 23

ALP can also be high in bone turnover in growing children

The Gamma- Glutamyl Transferase (Gamma GT) test needs to confirm it’s specifically from the liver

Question 24

What will you see in the LFTs in Pre-hepatic jandice?

Answer 24

• Raised unconjugated bilirubin
• Normal LFTs
• Associated anaemia

Question 25

What will you see in the LFTs in Pre-hepatic jandice?

Answer 25

• High levels of ALT and AST
• Usually normal ALP
• Mix of conjugated and unconjugated Bilirubin

Question 26

What will you see in the LFTs in Post-hepatic jandice?

Answer 26

• Raised levels of conjugated bilirubin
• Raised ALP
  
  • associated increase in gamma- GT
• ALT/ AST usually normal