ChemPath: Liver Disease Flashcards
How may the causes of high bilirubin be categorized?
- Pre-hepatic -usually due to haemolysis
- Hepatic - liver dysfunction
- Post-hepatic - usually due to bile duct obstruction
Where is bilirubin conjugated?
The liver
How do you measure conjugated and unconjugated bilirubin?
Van de Bergh Reaction
A direct reaction measures conjugated bilirubin
An indirect reaction measures unconjugated bilirubin
When may paediatric jaundice be normal and when may it be pathological?
Depends on time
<24 hours after birth - pathological
24 hours to 2 weeks after birth - physiological
>2 weeks after birth - pathological
How is jaundice treated in neonates?
Depends on transcutaenous bilirubin measurement
- Moderate hyperbilirubinaemia - phototherapy
- Severe hyperbilirubinaemia - exchange transfusion
What type of inheritance pattern does Gilberts syndrome have?
Recessive
How prevalent is Gilbert’s syndrome?
About 6% of people will have it (1 in 20) 50% carry the gene.
What would you expect to see on LFTs for Gilberts?
Normal LFTs and high (unconjugated) bilirubin. No need for liver biopsy.
What may exacerbate a high bilirubin level in Gilberts?
- Fasting
- Illness
- Dehydration
- Alcohol consumption
Describe the pathophysiology of Gilberts.
UDP glucuronyl transferase activity reduced to 30%. This causes a slightly raised unconjugated bilirubin but this does not enter the urine and cause bilirubinurea.
What does it mean if you have urobilinogen in the urine?
That the enterohepatic circulation is intact. Urobilinogen is always present in the urine of normal people. It comes from the entero-hepatic circulation. If you have a normal GIT, the bilirubin that you make goes into the biliary tree, into the bowel, then bacteria in the bowel converts a small amount of bilirubin into stercobilinogen which is the same as urobilinogen and is reabsorbed and you pee it out.
What does a lack of urobilinogen in the urine suggest?
Blockage of the biliary tree. If you block the biliary tree then the bacteria cannot see the bilirubin, you get pale stools, don’t make any urobilinogen which means urine becomes negative. If urine is negative for urobilinogen but they are jaundice, suggests physical obstruction to biliary tree.
What is the best measure of Liver Function?
- Prothrombin time (clotting factors PT, PTTK)
- Albumin
- Bilirubin
What do raised levels of all liver enzymes suggest?
Hepatitis
What does a high AST and ALT suggest?
Hepatocyte damage
What would an extremely high ALP suggest?
- Obstructive Jaundice
- Obstructive jaundice normally causes ALP to rise a lot. ALP will increase by the greatest of the enzymes with obstructive jaundice.