LECTURE 19 - Test of liver function Flashcards
What are the intracellular/ intrahepatic enzymes
ALT and AST
What are the bilary/ cholestatic enzymes
ALP
GGT
Billirubin
what percentage of bilirubin is uncongugated/indirect
85%
what is insoluble billirubin bound to
albumin
what form of bilirubin is soluble
bilirubin glucuronide
what does the bacteria in the gut convert billirubin gluconoride into
urobillinogen
what percentage of billirubin is conjugated/direct
15%
what is uncongugated billirugin
billirubin bound to albumen
what is conjugated billirubin
billirubin glucuronide
what happens to urobilinogen
either excreted in faeces or reabsorbed into the hepatic circulation
what are the 2 pathways of billirubin glucuronide
either into the bile where it is converted by bacteria in the gut into urobilinogen
OR
enters the bloodstream as billirubin glucuronide
what happens to billirubin when haemolysis occurs
billirubin bound to albumin increases and so dies urobiliongen which means it is more present in faeces and urine
what is ALT involved in
in making pyruvate in gluconeogenesis
where is ALT found
in the hepatocytes and the cytosol
which enzyme is the most liver specific
ALT
when is ALT high
in early and late hepatitis
What is AST involved in
in making glutamate in gluconeogenesis
where is AST foun
in hepatocytes and in cytosol and mtochondria
which has a shorter halflife AST or ALT
ALT has a longer half life (48hrs vs 8hrs)
when is AST high
in hepatitis
which enzymes are of billary origin
GGT and ALP
when is ALP high
in obstruction and inflammation of liver billary syst
When is GGT high
2-3 days after alcohol consumption, due to inflamation/obstruction of billary systm
when is billirubin elevated
in hepatitis or cancer
what does a elevated billirubin indicate
that your liver isn’t clearing billirubin properly
what does the prothrombin ratio refect
reflects clotting facor sysnthsis- rise indicates Vitamin K deficiency or liver faliure
what are the sources of albumin
liver is the only source
when does albumin levels fall
indicates impaired liver function
- decreased synthesis (cirrhosis)
- increased loss (eg kidney)
- illness
what does high globulin levels reflect
inflammation
when are globulin levels high
with chronic hepatitis/ cirrhosis
what does it mean if glucose is though
liver damage
what are the 2 categories of the causes of jaundice
unconjugated/ indirect
conjugated/ direct
what are the unconjugated/indirect causes of jaundice
haemolysis,
Gilbert’s syndrome= decrease in uptake of billirubin
what are the conjugated/ direct causes of jaundice
cholestasis- when bile can’t flow from the liver to the duodenum
obstruction inside liver (hepatitis, cirrhosis, masses)
obstruction outside liver- gall stones, billary/ pancreateic cancer, pancreatitis
what is Gilbert’s syndrome
decrease in uptake of billirubin
other liver function tests will be normal
illness/ fasting will worsen
common causes of viral hepatitis
infectious mono
hep a and b
causes of LFT abnormaliites
fatty liver
viral hepatitis
alchol
haemochromatosis
what does increased ammonia indicate
decreased liver function
