Use of Liver Enzymes in Diagnosis

Question 1

Which liver enzymes are cytoplasmic?

Answer 1

ALT, AST and LD

Question 2

Which liver enzymes are on the cell membrane?

Answer 2

ALP and GGT

Question 3

Which liver enzymes are in organelles?

Answer 3

mitochondrial AST and lysosomal SOD

Question 4

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

Answer 4

ALT, AST and LD

Question 5

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

Answer 5

ALP and GGT

Question 6

What is the action of ALT?

Answer 6

converts pyruvate to alanine in the Cori cycle

Question 7

What is the action of LD?

Answer 7

converts lactate to pyruvate in the Cori cycle

Question 8

What is the action of AST?

Answer 8

converts aspartate to glutamate

Question 9

Is there more AST or ALT in a hepatocyte?

Answer 9

AST because it is in the cytosol and in the mitochondria

Question 10

What is the key difference between AST and ALT?

Answer 10

ALT is specific to hepatocytes but AST is not

Question 11

Which lasts longer in the blood - AST or ALT?

Answer 11

ALT

Question 12

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

Answer 12

AST is higher in acute, ALT is higher in chronic

Question 13

What is the level of ALT in hepatitis A?

Answer 13

250 if mild, 1000 if moderate, 5000 if severe

Question 14

How can you distinguish between acute and chronic hepatitis B?

Answer 14

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

Question 15

What are some drugs which cause liver disease?

Answer 15

flucloxacillin, amoxil, statins, ethanol, paracetamol

Question 16

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

Answer 16

No - must have AST and ALT together if liver disease

Question 17

Are AST and ALT always high in cirrhosis?

Answer 17

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

Question 18

Where else is ALP apart from the liver?

Answer 18

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

Question 19

What is the action of GGT?

Answer 19

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

Question 20

What is the action of ALP?

Answer 20

adds phosphate groups

Question 21

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

Answer 21

huge elevation of GGT and ALP

Question 22

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

Answer 22

milder elevation of GGT and ALP

Question 23

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

Answer 23

no

Question 24

Why is GGT elevated in alcoholic liver disease?

Answer 24

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

Question 25

What is another cause of GGT elevation?

Answer 25

anti-epileptic drugs

Question 26

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

Answer 26

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

Question 27

What is the commonest cause of liver enzyme elevation?

Answer 27

obesity

Question 28

Do liver function tests indicate liver function?

Answer 28

no - they are markers of liver damage