Flashcards in OVERVIEW OF LIVER DISEASE AND LIVER FUNCTION TESTS Deck (80)
What are the two vascular inputs into the liver?
The portal vein
The hepatic artery
What does the portal vein carry?
Anything absorbed via intestine
What is first part metabolism?
The fact that all medication will going via the liver and will begin to be metabolised before going to the rest of the systemic circulation via the heart
What makes up the common hepatic duct?
The left and the right hepatic ducts
What does the common hepatic duct join with at its distal end?
The cystic duct coming from the gall bladder
What do the common hepatic duct and the cystic duct join to form?
The common bile duct.
Where do the endocrine products of the liver get put into the circulation?
The hepatic vein
What is the exocrine product made by the liver?
Where is bile stored?
How does bile get from the liver to the gall bladder?
It travels down the common hepatic duct and then retrogradely up the cystic duct
What are the cytotoxic blood factors of the liver?
AST (aspartate aminotransaminase)
ALT (alanine aminotransferase)
What are AST and ALT and why can they be used to recognise liver disease?
They are enzymes in the hepatocytes so when the hepatocytes die they are released into the circulation. This is similar to the cardiac enzymes that are used as markers of cardiac muscle death.
Will you always have high AST and ALT in liver failure?
No in the same way that you don't see prolonged raise in troponin with heart failure following an MI.
Broadly, what does elevated AST and ALT signify?
Inflammation in the liver
Does AST have high or low specificity for the liver?
Which hepatocyte is AST found in?
Does ALT have high or low specificity for the liver?
Will AST and ALT be elevated in chronic liver disease?
Often not. They are markers of acute injury.
What do AST and ALT tell you about residual function?
Nothing, they are purely markers of acute injury.
When AST and ALT start coming down, having been raised, is this always a good thing?
No. It could be a good thing because it could mean that the thing causing liver damage is no longer there, or no longer damaging the liver.
However, it could also mean that there are now significantly fewer hepatocytes to damages, indicative of nearing end stage liver failure.
AST and ALT tell you nothing about residual function.
Where is albumin made?
What is low albumin usually indicative of?
Chronic liver injury
Will albumin decrease in acute liver injury?
No. Because it has 20 day half life, so takes a while for levels to decrease.
What does an elevated INR tell you about whether liver injury is acute or chronic?
It doesn't. INR may be elevated in both.
What is the most sensitive part of the liver function tests in terms assessing injury?
INR. This will be the first thing to change with acute or chronic injury.
What are the clotting factors produced in the liver that will contribute to the elevated INR in liver injury?
Does INR tell you the extent of liver injury?
Yes, unlike AST and ALT, INR is a good marker for residualt function.
Other than liver disease, what else might cause a patient to have an elevated INR?
Drugs such as Warfarin
Low vitamin K
So as ALT is more specific to the liver than AST, which one is likely to be higher in acute liver injury?