Liver Function Test (AST | P)

Question 1

What are the functions of the liver?

Answer 1

1) It the site of metabolism
- > bile production
2) It functions in detoxification
3) It acts as a storage of carbs and fats
- > carbs (e.g. glycogen)
- > fats (e.g. lipoproteins and TAGs)
4) It functions for the synthesis of proteins (e.g. albumin)

Question 2

What is the meaning of AST?

Answer 2

Aspartate Aminotransferase

Question 3

What is the meaning of SGOT?

Answer 3

Serum Glutamic Oxaloacetic Transaminase

Question 4

What is the other term for AST?

Answer 4

SGOT

Question 5

What is AST?

Answer 5

It is the 1st marker / enzyme to increase in cases of liver disease but it is not specific

Question 6

What are the tissue sources for AST?

Answer 6

Widely distributed

Question 7

Since AST is widely distributed, where is AST highly concentrated?

Answer 7

1) Cardiac tissue
2) Liver
3) Skeletal muscle

Question 8

Since AST is widely distributed, the smallest concentrations of AST is present where?

Answer 8

1) Kidney
2) Pancreas
3) RBCs

Question 9

What are the diagnostic significance of AST?

Answer 9

1) For the evaluation of acute myocardial infarction (AMI)
2) W/ regards to hepatocellular disorders
3) W/ regards to skeletal muscle involvement
4) It is used in monitoring therapy w/ potentially hepatotoxic drugs
5) W/ regards to pulmonary embolism
6) W/ regards to congestive heart failure
7) AST is the highest in cases of acute hepatocellular disorders (such as viral hepatitis and cirrhosis); w/ regards to skeletal muscle

Question 10

W/ regards to the values of AST, if a pt has AMI, when does it:

1) Rise
2) Peak
3) Return to normal

Answer 10

1) 6 - 8 hrs
2) 24 hrs
3) After 4 - 5 days

Question 11

What is the signal of cessation of therapy whereas the utilization of potentially hepatotoxic drugs is present?

Answer 11

If results are 3x > the upper border / limit of normal values

Question 12

What is the result of the values of AST if a pt has viral hepatitis?

Answer 12

100x the result

Question 13

What is the result of the values of AST if a pt has cirrhosis?

Answer 13

4x the result

Question 14

What is the result of the values of AST w/ regards to skeletal muscle (or if pt has conditions related to skeletal muscle)?

Answer 14

4 - 8x the result

Question 15

What is the method present for AST?

Answer 15

Karmen method

Question 16

What is the principle of rxn of Karmen method?

Answer 16

L- Aspartate + alpha(sign)-ketoglutarate (via the action of AST) -> oxaloacetate + L- glutamate

oxaloacetate + NADH + H^+ (via the action of MDH) -> L- malate + NAD^+

Question 17

What are the sources of error for AST?

Answer 17

1) Hemolysis: 10x
2) Stability: 3 - 4 days at ref temp
3) Heparin: may inhibit the act of AST

Question 18

What is the process (or steps) for AST?

Answer 18

1) Prep the rgnt kit (pre-warming)
2) Label test tubes accordingly (blank, standard, unknown)
3) For each tube, add 1,000 uL of AST working rgnt
4) Add 100 uL sx to each test tube
5) Mix the tubes
6) Incubate for 5 mins
7) Read and record the A at 340 nm
8) Feed on the semi-automated machine

Question 19

What are the tubes present for AST?

Answer 19

1) AST + Blank
2) AST + Standard
3) AST + Serum

Question 20

What is the normal reference range of AST?

Answer 20

8 - 33 U/L