Liver function tests Flashcards
What are the current liver function tests?
- Serum aminotransferases for parenchymal injury (liver tissue)
- Serum bilirubin for cholesterol (tells if any stasis in biliary system)
- Serum alkaline phosphatase and gamma-glutamyltranspeptidase for biliary epithelial damage and biliary obstruction
- Serum albumin for hepatic synthetic function
- Prothrombin time for clotting
What is AST?
Aspartate aminotransferase, it is present in liver, cardiac muscle, kidney brain and many more. I can be released by damage to these tissues
What is ALT?
Alanine transaminase, it is present in cytoplasmic enzyme and has a similar distribution to AST
When investigating AST/ALT levels what would you measure?
Creatinine kinase, amylase/lipase (for pancreatitis) and cardiac troponin
If AST is raised and origin is the liver what does this suggest?
Hepatocyte damage, most likely from hepatitis, alcohol or drug abuse
What do raised transaminases and small increases in other tests indicate?
Hepatic liver damage
Why is paracetamol a major hepatic toxin?
If more than 10g is digested it creates an abundance of NAPQI, which decreases the liver’s natural antioxidant glutathione and directly damages cells in the liver, leading to liver damage
What two proteins and/or enzymes can you monitor to determine the hepatic health of an individual
AST and bilirubin, falling AST and bilirubin suggests hepatic recovery and good prognosis, but falling AST and rising bilirubin indicates critical loss of hepatocytes
What is bilirubin?
Bilirubin is a protein that is conjugated in the liver and excreted into the bile. It is produced when red blood cells are destroyed
Why do newborns have an overload of bilirubin?
Because they have immature hepatocytes
What is Gilbert’s syndrome?
A common autosomal dominant benign condition producing mild unconjugated hyperbilirubinaemia
