Use of Liver Enzymes in Diagnosis Flashcards Preview

Gastrointestinal > Use of Liver Enzymes in Diagnosis > Flashcards

Flashcards in Use of Liver Enzymes in Diagnosis Deck (28)
Loading flashcards...
1
Q

Which liver enzymes are cytoplasmic?

A

ALT, AST and LD

2
Q

Which liver enzymes are on the cell membrane?

A

ALP and GGT

3
Q

Which liver enzymes are in organelles?

A

mitochondrial AST and lysosomal SOD

4
Q

Which liver enzymes will be increased in the plasma due to necrosis of hepatocytes?

A

ALT, AST and LD

5
Q

Which liver enzymes will be increased in the plasma due to biliary disease (where the membrane is distressed)?

A

ALP and GGT

6
Q

What is the action of ALT?

A

converts pyruvate to alanine in the Cori cycle

7
Q

What is the action of LD?

A

converts lactate to pyruvate in the Cori cycle

8
Q

What is the action of AST?

A

converts aspartate to glutamate

9
Q

Is there more AST or ALT in a hepatocyte?

A

AST because it is in the cytosol and in the mitochondria

10
Q

What is the key difference between AST and ALT?

A

ALT is specific to hepatocytes but AST is not

11
Q

Which lasts longer in the blood - AST or ALT?

A

ALT

12
Q

Which is higher in an acute disease and which is higher in a chronic disease of AST and ALT?

A

AST is higher in acute, ALT is higher in chronic

13
Q

What is the level of ALT in hepatitis A?

A

250 if mild, 1000 if moderate, 5000 if severe

14
Q

How can you distinguish between acute and chronic hepatitis B?

A

the ALT level - very high (5000) if acute and lower (250) if chronic

15
Q

What are some drugs which cause liver disease?

A

flucloxacillin, amoxil, statins, ethanol, paracetamol

16
Q

If AST is the only liver enzyme which is high is it liver disease?

A

No - must have AST and ALT together if liver disease

17
Q

Are AST and ALT always high in cirrhosis?

A

No - if cirrhosis is so end stage that there are no hepatocyte left to release AST and ALT then the levels could be normal - this is a very bad sign

18
Q

Where else is ALP apart from the liver?

A

bone - good marker of bone disease - also produced in the placenta in pregnancy

19
Q

What is the action of GGT?

A

transfers glutamyl groups to amino acids - important in production of glutathione

20
Q

What is the action of ALP?

A

adds phosphate groups

21
Q

What are the liver enzymes like in an extra hepatic biliary obstruction?

A

huge elevation of GGT and ALP

22
Q

What are the liver enzymes like in an intra hepatic biliary obstruction?

A

milder elevation of GGT and ALP

23
Q

Is there a correlation between GGT level and amount of alcohol consumed?

A

no

24
Q

Why is GGT elevated in alcoholic liver disease?

A

ethanol leads to depletion of NAD+ which causes an up regulation of GGT to make glutathione

25
Q

What is another cause of GGT elevation?

A

anti-epileptic drugs

26
Q

Why is there never an absolute picture of hepatocellular death or biliary obstruction?

A

because biliary obstruction causes hepatocellular death and hepatocellular death causes biliary obstruction

27
Q

What is the commonest cause of liver enzyme elevation?

A

obesity

28
Q

Do liver function tests indicate liver function?

A

no - they are markers of liver damage