Jaundice Flashcards
What is jaundice?
Accumulation of bilirubin in the skin
What is bilirubin?
Breakdown product of haem
What is the clinical presentation of jaundice?
Yellow/orange tinge to skin and the sclera of the eyes.
Itch - bilirubin irritates nerve endings
What are the two forms bilirubin can be in?
Conjugated and non-conjugated
How does non-conjugated bilirubin become conjugated? What does this allow?
Conjugated bilirubin is bound to another molecule.
This allows it to be excreted from the body.
Why can non-conjugated bilirubin not be excreted from the body?
It isn’t water soluble
What is stool and urine colour dependant on?
Bilirubin conjugation
Where is bilirubin conjugated?
In the endoplasmic reticulum of hepatocytes
What are the 3 classifications of jaundice?
Prehepatic
Hepatic
Post hepatic
What causes pre hepatic jaundice?
Accumulation of bilirubin due to excessive RBC breakdown;
Haemolytic anaemia
Post-transfusion
Neonataal mixing
Gilberts syndrome
How does haemolytic anaemia cause pre hepatic jaundice?
RBC’s are broken down quicker than they are produced = accumulation of bilirubin
Due to the increased levels - some of the bilirubin bypasses the hepatocyte uptake and unconjugated bilirubin remains in the blood.
How does a blood transfusion cause pre hepatic jaundice?
If there is an inaccurate blood match the immune system will attack the RBC and cause them to be broken down releasing bilirubin.
How does neonatal mixing cause pre hepatic jaundice?
Mother and baby’s blood mix during birth - baby’s immune system targets the mothers RBC causing them to be broken down = bilirubin release.
What is the consequences of neonatal mixing?
Accumulation of bilirubin can lead to Kernicterus - brain damage and damage to nerve fibres.
This can be permanent.
How is neonatal jaundice treated?
Phototherapy - baby placed under a blue light which breaks down bilirubin in the skin.
How does Gilbert’s disease cause pre hepatic jaundice?
There is a decreased bilirubin uptake by the hepatocytes - unconjugated bilirubin remains in the blood.
What are the hepatic causes of jaundice?
Prevents metabolism of harm breakdown products
Cirrhosis
Drug induced
Impaired enzyme action
Secretory failure
How does cirrhosis cause hepatic jaundice?
There is a reduction in hepatocytes and same levels of bilirubin = an accumulation
How does impaired enzyme activity cause hepatic jaundice?
Unconjugated bilirubin cannot be conjugated since hepatocytes are non-functioning due to disease.
How does secretory failure cause hepatic jaundice?
non-conjugated bilirubin is taken up by the hepatocytes and conjugated yet cannot leave the hepatocyte due to the membrane becoming impermeable.
What are the post-hepatic causes of jaundice?
Bile outflow blockage
Intrahepatic
Primary biliary sclerosis
Extrahepatic
Gallstones
Carcinoma of the head of the pancreas
Cholangiocarcinoma
What occurs in post-hepatic jaundice?
Unconjugated bilirubin enters the hepatocytes is conjugated and passes out of the hepatocyte via the bile canaliculus.
The conjugated bilirubin then encounters a blockage and is forced back up into the hepatocyte and into the blood
How does primary biliary sclerosis cause post hepatic intrahepatic jaundice?
Immune system attacks the bile duct causing scarring and narrowing/obstruction.
How do gallstones cause post hepatic extrahepatic jaundice?
Gallstones move out of the gallbladder and into the biliary tree where they can cause blockages.
How does pancreatic cancer cause post hepatic extrahepatic jaundice?
Pancreatic tumours commonly occur at the head of the pancreas.
Common bile duct lies near the head of the pancreas so as the tumour grows it blocks the bile duct and obstructs outflow of conjugated bilirubin
How do cholangiocarcinomas cause post hepatic extrahepatic jaundice?
Tumour of the bile duct so causes blockage of the bile duct as it grows
What are the clinical features of pre-hepatic jaundice?
Dark stool and dark urine
What are the clinical features of hepatic jaundice?
Pale stool and pale urine
What are the clinical features of post-hepatic jaundice?
Pale stool and dark urine
What are the symptoms of gallstones? When do they occur?
Pain on shoulder tip
Abdominal pain on the right side
Pain occurs when eating fatty foods.
Fat triggers the contraction of the gallbladder to release bile which emulsifies fat.
How do you investigate/image the jaundiced patient?
Ultrasound
Radiographs (however not all gallstones are radiopaque)
Endoscopic retrograde cholangiopancreatography
Dye injected into the biliary tree to highlight obstructions.
What are the functions of an endoscopic retrograde cholangiopancreatography?
Injects die to highlight blockages;
Places a stent (when bile ducts compresses by tumour)
Can make an incision to free the gallstones
How do you treat post-hepatic jaundice?
Remove the obstruction:
ERCP:
Stent (tumour)
Incision (gallstones)
Lithotripsy - sonic waves to destroy gallstones.
How do you prevent gallstones?
Remove gallbladder
Prevent the accumulation of bile via low calorie / low cholesterol diet.
Reduce the amount of bile resorption by the GIT via colestyramine drug.
