Session 6: Jaundice and LFTs

Question 1

Define jaundice

Answer 1

Clinical manifestation of raised bilirubin presenting as yellowish sclera and skin.

Question 2

What is bilirubin?

Answer 2

Breakdown product of haem.

Question 3

What are the two forms of bilirubins found in the body?

Answer 3

Unconjugated and conjugated bilirubin.

Question 4

What is unconjugated bilirubin?

Answer 4

Not water soluble and bound to albumin.

Question 5

What is conjugated bilirubin?

Answer 5

Conjugation of bilirubin in the liver making it water soluble.

Question 6

What are the options of bilirubin to go in the body?

Answer 6

Kidneys as urobilinogen and get excreted. Urobilinogen excreted in faeces. (What makes faeces brown) Enter the enterohepatic circulation with bile and then excreted.

Question 7

Causes of jaundice (very broad).

Answer 7

Pre-hepatic Hepatic Post-hepatic

Question 8

Pathogenesis of pre-hepatic jaundice.

Answer 8

Due to too much haem. This is because increased degradation of haemoglobin. The liver conjugating is still fine and the excretion pathway also. However there is too much demand on the liver and this leads to an increased level of bilirubin that is unconjugated.

Question 9

Common causes of pre-hepatic jaundice.

Answer 9

Haemoglobinopathies like sickle cell, thalassaemia and spherocytosis. Damage to red blood cells like haemolysis like MAHA

Question 10

What is hepatic jaundice due to?

Answer 10

Reduced hepatocyte function.

Question 11

Explain hepatic jaundice.

Answer 11

Caused by reduced conjugating ability of the liver. This is due to damage of the hepatocytes where the amount of bilirubin is fine and the excretion pathway is fine. This leads to a mix of conjugated and unconjugated bilirubin.

Question 12

Common causes of hepatic jaundice.

Answer 12

Cirrhosis like alcoholic fatty liver disease, NAFLD, drugs, autoimmune, depositions, hepatitis, infections, hereditary haemochromatosis, Wilson’s disease etc… Can also be caused by acute liver damage like paracetamol toxicity, viral hepatitis etc…

Question 13

Explain post-hepatic jaundice.

Answer 13

Caused by obstruction to the excretion pathway. Amount of bilirubin is fine and the conjugating ability is usually fine as well. This means that there will be an increase in conjugated bilirubin.

Question 14

How can you distinguish between raised levels of unconjugated bilirubin and conjugated?

Answer 14

Unconjugated will still eventually make it into the normal pathway in normal doses to become conjugated. It just takes more time. Unconjugated will not be excreted in urine because it is not water soluble. Raised conjugated levels will lead to increased bilirubin excreted in kidney and therefore darker urine and pale stools.

Question 15

Common causes of post-hepatic jaundice.

Answer 15

Gallstones Biliary stricture Pathology of the head of the pancreas. Intrahepatic pathology can also lead to compression of the intrahepatic bile ducts. Like in the case of oedema, malignant growth or scarring.

Question 16

LFTs

Answer 16

Bilirubin - conjugated vs unconjugated Albumin ALT AST ALP

Question 17

Will albumin levels rise or decrease in reduced liver function?

Answer 17

Less albumin

Question 18

What does low albumin cause?

Answer 18

A reduction in oncotic pressure leading to oedema and ascites.

Question 19

What other body system might lead to low albumin levels?

Answer 19

Kidney injury

Question 20

What is ALT and AST?

Answer 20

Alanine transaminase Aspartate transaminase Hepatic enzymes that increase in conc. when the hepatocytes are damaged.

Question 21

What is more specific to the liver; ALT or AST? Why?

Answer 21

ALT is more specific AST can also be found in cardiac/skeletal muscle as well as in red blood cells.

Question 22

What rises more in acute liver damage? ALT or AST?

Answer 22

ALT > AST

Question 23

What rises more in cirrhosis and alcoholic hepatitis? ALT or AST?

Answer 23

AST > ALT

Question 24

Where can ALP be found?

Answer 24

Found in the cells lining the bile ducts.

Question 25

When do the levels of ALP rise?

Answer 25

In cholestasis i.e. bile duct obstruction.

Question 26

ALP is not specific to bile duct obstruction. When else can it be found?

Answer 26

It is also used to assess bone turnover.

Question 27

What can be used to specify the source of increased ALP?

Answer 27

Gamma-Glutamyl Transferase (Gamma GT) to specify the source as liver.

Question 28

LFTs of pre-hepatic jaundice.

Answer 28

Usually no abnormalities of LFTs other than raised levels of unconjugated bilirubin and associated anaemia.

Question 29

LFTs of hepatic jaundice.

Answer 29

Mixed bilirubin. High lvls of ALT and AST Usually normal ALP

Question 30

LFTs of post-hepatic jaundice.

Answer 30

Raised levels of conjugated bilirubin. Raised ALP Usually normal ALT/AST

Question 31

17 yr old admitted having ingested two packets of paracetamol.

They are drowsy, have some abdo pain and feel nauseous. They appeard jaundiced.

Answer 31

Hepatic jaundice

Shows hepatocellular damage

Acute liver damage as ALT is raised considerably.

Question 32

42 y old admitted with epigastric pain radiating to her back.

Odd niggly with stomach pain every now and then but not as bad at this. Feels nauseous and has vomited this morning.

Answer 32

Raised ALP indicating obstructive pattern. No signs of jaundice.

Test Cullen’s sign, Grey Turner’s sign, Gamma GT as well as amylase and lipase to confirm acute pancreatitis.

Question 33

Answer 33

C

Question 34

Answer 34

E