Jaundice refers to the yellow discolouration of the sclera and skin (Fig. 1) that is due to hyperbilirubinaemia, occurring at bilirubin levels roughly greater than 50 µmol/L (Normal levels: 3.4 to 20)
Bilirubin is the breakdown product from the catabolism of haem, bilirubin should be conjugated in the liver (making it water soluble), it is then excreted via bile into the GI tract. The majority of which is egested in the faeces as urobilinogen and stercobilin (the metabolic breakdown product of urobilingoen). Around 10% of urobilinogen is reabsorbed into the bloodstream and excreted through the kidneys. Jaundice occurs when this pathway is disrupted.
GREEN - Common causes
RED - Less common
Pre-hepatic:
excess RBC breakdown
= unconjugated hyperbilirubinaemia
Causes:
Hepatocellular:
dysfunctional hepatocytes = inability to conjugate. Liver can also become cirrhotic and compress the intrahepatic portions of the biliary tree causing a degree of obstruction.
= Both conjugated and unconjugated bilirubin in blood
Causes: