Jaundice is detectable when serum bilirubin > 40 micromoles/L. It can be due to a number of causes including liver disease and haemolysis
About
- Yellowish discolouration in skin and sclera that represents Bilirubin
- Bilirubin is a breakdown of haem
Physiology
- Red cells are broken down naturally and breakdown products are reused
- Haem is broken down in spleen and transported in the blood bound to albumin
- The enzyme is glucuronyl transferase and forms bilirubin glucuronide
- In the liver Haem is conjugated to make it water-soluble and excreted in the bile
- This is reabsorbed in the terminal ileum and excreted by kidneys
- Or further broken down to stercobilinogen and excreted in faeces
Prehepatic Causes (raised unconjugated bilirubin)
- Haemolysis, Gilbert's syndrome and Crigler-Najjar
- Haemolysis: Anaemia, Raised reticulocytes, LDH
Hepatic Causes (raised conjugated bilirubin)
- Dubin-Johnson, Rotor syndrome, Liver congestion
- Viral hepatitis A, B, C, EBV, Drug-induced - phenothiazines
- Cirrhosis, Alcoholic liver disease, Liver metastases
- Raised AST/ALT suggests hepatitis/congestion
- Raised ALP/GGT may also be seen
- USS Liver shows cirrhosis or metastases
Post hepatic Jaundice(raised conjugated bilirubin)
- Gallstones occluding CBD, Pancreatic cancer
- Lymph nodes occluding CBD/Porta hepatitis
- Primary sclerosing cholangitis, Biliary tree stricture
- USS Biliary system identifies obstruction and gallstones
- Raised ALP and GGT suggests cholestasis
- Pale stools and dark urine (Bilirubin which gives stool its normal colour cannot enter the gut)
Investigations
- Elevated Bilirubin > 40-50 umol/L when clinically evident
- Preheptic: raised unconjugated (indirect) bilirubin