Liver Function Tests Flashcards
In which types of jaundice do you see a raised unconjugated bilirubin level?
Pre-hepatic - increased bilirubin production
Hepatic - defects in UCB uptake or conjugation (e.g. Gilbert’s)
In what types of jaundice is conjugated bilirubin raised?
Hepatic - blockage to bile excretion from liver (can be caused by acquired or inherited factors)
Post-hepatic - cholestasis
What are asparate aminotransferase and alanine aminotransferase markers of?
Hepatocellular injury - probably hepatitis
Why would a person be given a liver function test?
- Well person screening
- To investigate unexplained symptoms
- To investigate symptoms and signs suggesting of liver disease
- For pre-operative or baseline assessment
- To monitor the progressive of established liver disease and assess the response to treatment
What is the benefit of testing someone for GGT, despite it having a low specificity for liver disease?
It can be used to identify whether raised ALP is of liver origin and can detect chronic alcohol consumption.
Why is GGT raised in people with chronic alcohol consumption?
Because alcohol processing happens in the mitochondria of liver cells, and GGT is a mitochondrial isoenzyme
In what two scenarios is ALP likely to be raised?
- cholestasis
- bone disease (commonly high in growing children)
Which common plasma protein is the only one not to be produced in the liver?
Immunoglobulins
What happens to prothrombin in the liver, and why is this important?
It gets converted to thrombin - and so the PTT is a good indicator of liver function.
This slower it happens, the worse the liver function is
What happens to albumin as hepatitis/cholestatic diseases progress from acute to chronic?
Albumin decreases from normal levels (acute) to abnormally low levels (chronic)
What tests should be done if the patient has suspected cholestasis to confirm this diagnosis?
An ultrasound or percutaneous cholangiography
If ALT and AST is raised, what tests should you perform?
Serology - viral hepatitis - autoantibodies (- ferritin studies - alpha-1-antitrypsin concentration) Biopsy - done if the serology is unhelpful and LFTs are persistently high
If cholestasis is suspected, but no dilated ducts are seen on an ultrasound, what should you test for next?
Anti-mitochondrial antibodies - hepatic obstruction
Out of ALT and AST, which would rise more in alcoholism?
AST
