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
