05 - Liver values

Question 1

(ALT - leakage enzyme)

1. liver specific?
2. tests for what?

Answer 1

1. no; see ^ in severe musc injury
2. hepatocyte injury

Question 2

(AST - leakage enzyme)

1. liver specific?
2. ^ AST = ?
3. how specific vs ALT?

Answer 2

1. no - present in hepatocytes and in skeletal and cardiac musc
2. hepatocyte death/injury, musc death/injury
3. less specific

Question 3

(SDH - leakage enzyme)

1. specific to liver?
2. ^SDH = ?
3. how long is half life?
4. better than AST in what species?

Answer 3

1. yes!
2. hepatocyte death/injury
3. very short (values back to normal in a few days)
4. horses/ruminants

Question 4

(glutamate dehydrogenase - GLDH)

1. liver specific?
2. ^ = ?
3. how stable vs SDH?

Answer 4

1. yes
2. hepatoctye death or injury
3. more stable but not by much

Question 5

(tests for cholestasis)

(ALP - induced enzyme)

1. ^ by what 3 things?
2. in what animal is half-life very short? (6 hrs)

Answer 5

1. osteoblast activity (young animals), cholestasis, corticosteroids/anticonvulsants
2. cats

Question 6

(GGT)

1. ^ usually = ?
2. can be induced by what drugs?
3. better than ALP is what species?

Answer 6

1. cholestasis
2. glucocorticoids and anticonvulsants
3. large animals

Question 7

(liver fx tests - bilirubin)

1. normal metabolism: unconjugated bilirubin enters hepatocytes -> conjugated and secreted into bile (small amount goes back into blood)
2. What are three causes of ^ bilirubin?

Answer 7

2. ^ hemoglobin production (^ RBC destruction)

dec uptake and conjugation of bilirubin by hepatocytes

decrease in outflow of conjugated bilirubin (cholestasis)

Question 8

(liver fx tests - bile acids)

1. what samples are collected?
2. ^ in bile acid level in circulation caused by what 4 things?
3. what is the basic bile acid cycle?

Answer 8

1. fasting and postprandial
2. PSS, hepatic microvascular dysplasia, intrahepatic cholestatic dz, extrahepatic bile duct obstruction
3. made in liver -> secreted into duodenum via bile duct -> reabsorbed later at ileum -> portal vein back to liver

Question 9

(liver fx - ammonia)

1. ^ when?
2. ammonia levels increase in the blood when the liver is not able to do what?

Answer 9

1. PSS or 60% liver mass lost
2. convert ammonia to urea

Question 10

albumin decreases when what % of liver fx is lost?

Answer 10

60 to 80%

Question 11

(glucose)

1. liver converts glucose into what?
2. glucose may be increased when?
3. glucose may be decreased when?

Answer 11

1. glycogen
2. decreased glucose uptake by liver
3. if there is decreased gluconeogenesis or glycogenolysis

Question 12

(urea is synthesized in the liver from ammonia)

1. what happens to BUN w/ liver failure?
2. blood ammonia?

Answer 12

1. decrease
2. increase

Question 13

(cholesterol)

1. can be decreased when?
2. can be increased when?

Answer 13

1. decreased synth in liver failure
2. cholestasis (prevents excretion of cholesterol in bile)