Gastroenterology assessment - Jaundice

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