Friday, 19 November 2010

MRCP revision battle 54.2: Jaundice

Jaundice is yellow pigmentation of the skin caused by raised bilirubin.

It is generally clinically visible above 35micromol/l.

The 'story' of bilirubin is illustrated in the diaphragm below:
  • phagocytes break haemoglobin down into unconjugated (=insoluble) bilirubin
  • unconjugated bilirubin is joined with glucoronic acid in the liver, making it conjugated (=soluble)
  • conjugatde bilirubin passes into the gallbladder and on to the small intestine, where it is converted into urobilinogen and excreted in urine by the kidneys or to stercobilinogen and excreted in faeces

The types of jaundice are:

1. Pre-hepatic = unconjugated
  • caused by:
    • haemolysis
    • lack of UDP: Gilberts, Crigler Najjar
  • urine/faeces colours normal

2. Hepatic = both conjugated and unconjugated
  • caused by:
    • infection: HBV, HCV, EBV
    • Wilsons
    • Budd-Chiari
    • Dubin-Johnson/Rotor syndromes
    • cirrhosis
    • drugs:
      • anti-TB meds
      • statins
      • sodium valproate
      • MAOIs
      • halothane
      • paracetamol OD
  • urine dark, faeces normal

3. Post-hepatic = conjugated = obstructive/cholestatic
  • gallstones
  • pancreatic cancer
  • cholangiocarcinoma
  • primary bilary sclerosis
  • sclerosing cholangitis
  • Mirrizi's syndrome = obstructive jaundice secondary to compression of the common hepatic duct by a gallstone impacted in the cystic duct
  • Drugs
    • antibiotics - co-amoxiclav, nitrofurantoin, flucloxacillin
    • OCP
    • chlorperazine
    • sulphonylureas
    • anabolic steroids
  • urine pale and faeces pale

Now for something different... PDA...