Jaundice Flashcards
Describe the key events in bilirubin metabolism
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
At what level of bilirubin is jaundice visible?
50umol/L
How can jaundice be classified?
Pre-heaptic
Hepatocellular
Obstructive/cholestatic
What causes pre-hepatic jaundice?
Increased RBC breakdown
- haemolysis
- haematoma reabsorption
What is the key feature of the bilirubin in pre-hepatic jaundice?
Unconjugated (not processed by liver)
What causes cholestatic jaundice?
Obstruction to bile outflow from liver
-intrahepatic or extrahepatic
What are the key features of the bilirubin in hepatic jaundice?
Conjugated (processed by liver) Cannot enter GI tract, not excreted in faeces -pale stools Enters kidneys, excreted in urine -dark urine
What are the causes of intrahepatic cholestatic jaundice?
Obstruction of hepatic bile canaliculi
- hepatitis
- cirrhosis
- neoplasm
- drugs (chlorpromazine, flucloxacillin, isoniazid, OCP)
- pregnancy
What are the causes of extrahepatic cholestatic jaundice?
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)
What causes hepatocellular jaundice?
Hepatocytes dysfunctional, partial/total inability to conjugate bilirubin
- hepatitis
- cirrhosis
- neoplasm
- hepatotoxic drugs (paracetamol, methyldopa, barbiturates)
- Gilbert’s syndrome
What is Gilbert’s syndrome?
Congenital lack of gluconyltransferase
Affects 7% of population
No clinical significance, transient episodes of jaundice post-infection
What are the urine/stool changes in prehepatic jaundice?
Normal/dark stools
Normal urine
What are the urine/stool changes in obstructive/cholestatic jaundice?
Pale stools
Dark urine
What are the urine/stool changes in hepatocellular jaundice?
Pale stools
Normal/dark urine
What non-invasive investigations are appropriate in jaundice?
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?)
What LFT changes can be used to distinguish the cause of jaundice?
Transaminases - raised in hepatocellular jaundice/intrahepatic obstruction
ALP - raised in extrahepatic cholestasis
What further investigations may be appropriate in jaundice?
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
What are the key features of an ERCP?
Endoscopic retrograde cholangiopancreatography
- ampulla of vater cannulated
- contrast injected to demonstrate lesions
- used therapeutically (biliary stenting/biopsy)
- ciprofloxacin given as antibiotic prophylaxis
What are the potential complications of an ERCP?
Pancreatitis
Bleeding
Perforation
Cholangitis
What are the key features of a PTC?
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
