Liver Flashcards
Describe the metabolism of bilirubin
Post mature erythrocytes are broken down in the reticual endothelial system into haem and unconjugated bilirubin
Unconjugated bilirubin - indirect bilirubin (water insoluble)
Unconjugated bilirubin is transported to the liver by albumin
The liver conjugates unconjugated bilirubin by adding glucuronic acid (direct bilirubin – water soluble)
Most of the bilirubin in bile (80%) is excreted in stool
The rest (20%), is either excreted in urine or taken back into the enterohepatic circulation
Pre-hepatic jaundice
Mostly unconjugated (indirect, water soluble)
Intrahepatic jaundice
Mixed conjugated and unconjugated
Post-hepatic jaundice (cholestasis)
Mostly conjugated (water soluble)
Liver function tests
Bilirubin - total, split ALT - alanine aminotransferase AST - aspartate aminotransferase Alkaline phosphate GGT - gamma glutamyl transferase
When is jaundice usually visible?
Bilirubin >40-50umol/l
Early neonatal jaundice
<24hrs old
Always pathological
What are the causes of early neonatal jaundice?
Haemolysis - ABO incompatibility, G6PD deficiency, hereditary spherocytosis
Sepsis
(unconjugated)
How is neonatal jaundice treated?
Phototherapy
Intermediate neonatal jaundice
24hrs - 2 weeks
What are the causes of intermediate neonatal jaundice?
Physiological Breast milk Sepsis Haemolysis (unconjugated)
What are reasons for haemolysis?
ABO incompatibility
Rhesus disease
Red cell membrane defects – spherocytosis
Red cell enzyme defects – G6PD
What are the complications of neonatal jaundice?
Kernicterus - unconjugated bilirubin can cross the blood brain batteries and cause neurotoxic deposits in the brain
Prolonged infant jaundice
Jaundice persisting >2 weeks (>3 if pre-term)
What are the causes of prolonged infant jaundice?
Conjugated (abnormal) - extra hepatic obstruction (biliary atresia, choledochal cyst), neonatal hepatitis
Unconjugated - hypothyroidism, breast milk
How is prolonged infant jaundice investigated?
Split bilirubin most important
Always look at stool colour
Ultrasound
Assessment targeted at diagnosing biliary atresia early
What is biliary atresia?
Congenital fibro-inflammatory disease of the bile duct leading to destruction of extra-hepatic bile ducts
What is the presentation of biliary atresia?
Prolonged, conjugated jaundice
Pale stool
Dark urine
How is biliary atresia treated?
Kasai portoenterostomy
What investigations would be done in an infant presenting with jaundice?
Split bilirubin DAT FBC, reticulocyte count, LFTs Blood film G6PD assay Urine MC&S
