Jaundice

• Jaundice is the name given when excess bilirubin (typically greater than 35 µmol/L) accumulates and becomes visible as a yellow discolouration of the sclera and/or skin
• • Bilirubin is formed from the breakdown of haemoglobin
  • Conjugated with glucuronic acid by hepatocytes, making it water soluble
  • Conjugated bilirubin is secreted into bile and passes into the duodenum
  • Some is taken up again by the liver to make more bile
  • The rest of converted to urobilinogen by gut bacteria
  • It is either then reabsorbed and excreted by the kidneys or converted to stercobilinogen and excreted in faeces
• Bilirubin is not water soluble so it relies on albumin to be transported to the liver. Once in the liver, glucuronic acid is added to make conjugated bilirubin
• Jaundice can be broadly divided into:

  • Pre-hepatic jaundice
  • Intrahepatic jaundice
  • Post-hepatic jaundice
• Causes of pre-hepatic jaundice:

  • Haemolytic anaemias
  • Gilbert's syndrome
• Causes of intrahepatic jaundice:

  • Viral hepatitis
  • Autoimmune hepatitis
  • Alcoholic hepatitis
  • Drug-induced hepatitis
  • Decompensated cirrhosis
  • Intrahepatic cholestasis
• Causes of extrahepatic jaundice:

  • Common bile duct stone
  • Cholangitis
  • Bile duct strictures
  • Malignancy
  • Pancreatitis
• Pre-hepatic jaundice occurs when bilirubin metabolism has been affected before bilirubin reaches the liver (i.e., unconjugated bilirubin).

  Generally, this type of jaundice is caused by issues relating to red cell breakdown, where increased haemolysis results in excess bilirubin.

  The liver is unable to conjugate all of the bilirubin
• Intrahepatic jaundice occurs when hepatocyte damage results in reduced bilirubin conjugation or structural abnormalities that cause cholestasis. Dark urine and pale stool will occur if there is cholestasis.
• Gallstones in the common bile duct are one of the most common causes of extrahepatic cholestasis and therefore jaundice. Cholestasis leads to dark urine as the bilirubin is still still conjugated and pale stools as inadequate bilirubin reaches the colon
• The bile duct can be obstructed by head of pancreas malignancy or cholangiocarcinoma - this causes extrinsic compression
• Extrahepatic Jaundice can occur in pancreatitis for several reasons: common bile duct stone, excess alcohol use or extrinsic compression of the common bile duct due to an increase in the size of the pancreas due to severe inflammation