Jaundice

Question 1

Describe the key events in bilirubin metabolism

Answer 1

RBC reach end of life span (120 days)
Destroyed in reticuloendothelial system
Haem –> biliverdin –> bilirubin (bound by albumin)
Bilirubin taken up by hepatocytes
-conjugated by glucuronyl transferase –> bilirubin glucuronide (soluble)
-soluble bile excreted in bile into bowel –> urobilinogen
-urobilinogen excreted via gut/reabsorbed
-reabsorbed urobilinogen excreted via kidneys

Question 2

At what level of bilirubin is jaundice visible?

Answer 2

50umol/L

Question 3

How can jaundice be classified?

Answer 3

Pre-heaptic
Hepatocellular
Obstructive/cholestatic

Question 4

What causes pre-hepatic jaundice?

Answer 4

Increased RBC breakdown

• haemolysis
• haematoma reabsorption

Question 5

What is the key feature of the bilirubin in pre-hepatic jaundice?

Answer 5

Unconjugated (not processed by liver)

Question 6

What causes cholestatic jaundice?

Answer 6

Obstruction to bile outflow from liver

-intrahepatic or extrahepatic

Question 7

What are the key features of the bilirubin in pre-hepatic jaundice?

Answer 7

Conjugated (processed by liver)
Cannot enter GI tract, not excreted in faeces
   -pale stools
Enters kidneys, excreted in urine
   -dark urine

Question 8

What are the causes of intrahepatic cholestatic jaundice?

Answer 8

Obstruction of hepatic bile canaliculi

• hepatitis
• cirrhosis
• neoplasm
• drugs (chlorpromazine, flucloxacillin, isoniazid, OCP)
• pregnancy

Question 9

What are the causes of extrahepatic cholestatic jaundice?

Answer 9

Obstruction of hepatic ducts/biliary tree

• causes w/i lumen (gallstones)
• causes w/i wall (cholangiocarcinoma, 1o sclerosing cholangitis, congenital atreasia of CBD)
• external causes (pancreatitis, tumour of pancreatic head)

Question 10

What causes hepatocellular jaundice?

Answer 10

Hepatocytes dysfunctional, partial/total inability to conjugate bilirubin

• hepatitis
• cirrhosis
• neoplasm
• hepatotoxic drugs (paracetamol, methyldopa, barbiturates)
• Gilbert’s syndrome

Question 11

What is Gilbert’s syndrome?

Answer 11

Congenital lack of gluconyltransferase
Affects 7% of population
No clinical significance, transient episodes of jaundice post-infection

Question 12

What are the urine/stool changes in prehepatic jaundice?

Answer 12

Normal/dark stools

Normal urine

Question 13

What are the urine/stool changes in obstructive/cholestatic jaundice?

Answer 13

Pale stools

Dark urine

Question 14

What are the urine/stool changes in hepatocellular jaundice?

Answer 14

Pale stools

Normal/dark urine

Question 15

What non-invasive investigations are appropriate in jaundice?

Answer 15

Bloods - FBC, reticulocytes, LFTs, U&Es, clotting, bilirubin
Urinary urobilinogen/bilirubin
Glucose - low in liver failure/raised in pancreatic
Coomb’s test (pre-hepatic?)
Viral serology (hepatitis?)

Question 16

What LFT changes can be used to distinguish the cause of jaundice?

Answer 16

Transaminases - raised in hepatocellular jaundice/intrahepatic obstruction
ALP - raised in extrahepatic cholestasis

Question 17

What further investigations may be appropriate in jaundice?

Answer 17

USS - show obstruction of duct system
MRCP - non-invasive, high res image of biliary tree
CT/MRI - demonstrates intahepatic/pancreatic lesions
Needle biopsy - hepatitis/cirrhosis
ERCP
PTC

Question 18

What are the key features of an ERCP?

Answer 18

Endoscopic retrograde cholangiopancreatography

• ampulla of vater cannulated
• contrast injected to demonstrate lesions
• used therapeutically (biliary stenting/biopsy)
• ciprofloxacin given as antibiotic prophylaxis

Question 19

What are the potential complications of an ERCP?

Answer 19

Pancreatitis
Bleeding
Perforation
Cholangitis

Question 20

What are the key features of a PTC?

Answer 20

Percutaneous transhepatic cholangiography

• cannulation of dilated bile duct w/i liver
• used for therapeutic intervention if ERCP not possible
• does not allow ampulla/pancreatic duct visualisation
• can be used for stenting