Liver Enzymes

Question 1

What are the functions of the liver? (4)

Answer 1

1. metabolism of carbohydrates, fats
2. synthesis of albumin, clotting factors
3. secretion of bilirubin
4. metabolism and elimination of toxins and drugs

Question 2

What are the enzymes associated with hepatocellular injury? (3)

Answer 2

1. Alanine Aminotransferase (ALT)
2. Aspartate Aminotransferase (AST)
3. Sorbitol Dehydrogenase

Question 3

Alanine Aminotransferase (ALT) 
(What is it good for?) (2)

Answer 3

• Liver specific in dogs and cats

- Not liver specific in horses, cattle, swine

Question 4

Aspartate Aminotransferase (AST) 
(What is it good for?)

Answer 4

• Not liver specific but best for horses

Question 5

Sorbitol Dehydrogenase

What is it?) (2

Answer 5

• liver specific in all species

- not routinely measured

Question 6

What are the enzymes associated with obstruction of bile flow?(4)

Answer 6

1. Alkaline Phosphatase (Alk Phos)
2. Gamma Glutamyltranspeptitase/Gluamyltransferase (GGT)
3. Bilirubin
4. Bile Acids

Question 7

Alkaline Phosphatase (Alk Phos) 
(What is it?) (3)

Answer 7

• Not liver specific
• useful in dogs and cats
• not useful in horses, cattle

Question 8

Gamma Glutamyltranspeptitase/Gluamyltransferase (GGT)

What is it?) (3

Answer 8

• liver is primary source
• works well in small, large animal species
• use of glucocorticoids and anticonvulsants may increase levels

Question 9

What is Bilirubin?

Answer 9

• derived from hemoglobin released by lysed RBC

Question 10

Bile Acids 
(What is it and what does it do?) (2)

Answer 10

• substances produced by the liver and secreted in bile to promote the digestion and absorption of fat from the small intestine
• bile acids are reabsorbed from the small intestine and removed from circulation by the liver

Question 11

What do increased levels of Bile Acids tell us?

Answer 11

may be increased in portosystemic shunts (young animals), chronic liver disease

Question 12

What do increased levels of Bilirubin tell us?

Answer 12

Increased levels associated with increased RBC destruction or liver disease

Question 13

What do increased levels of Alk Phos tell us?

Answer 13

increased levels often seen with bone marrow injury, rapidly growing animals, use of glucocorticoids and anticonvulsants

Question 14

What do increased levels of Alanine Aminotransferase (ALT) indicate?

Answer 14

Increased levels may also be due to drug administration (glucocorticoids, anticonvulsants)

Question 15

What do increased levels of Aspartate Aminotransferase (AST) indicate?

Answer 15

increased levels seen with muscle inflammation, hemolysis of blood sample

Question 16

Alkaline Phosphatase (Alk Phos) is it an early warning sign for what?

Answer 16

Cushing’s Disease

Question 17

What causes an false increase in Bilirubin? (2)

Answer 17

• avoid exposure of blood sample to light

- lipemia and hemolysis of blood sample may lead to falsely elevated readings

Question 18

What causes an increase in Gamma Glutamyltranspeptitase/Gluamyltransferase (GGT)?

Answer 18

use of glucocorticoids and anticonvulsants may increase levels