Hepatobiliary (dilini)

Question 1

Which enzymes are associated with cholestasis?

Answer 1

Alkaline phosphatase (ALP)
Gama glutamyl transferase (GGT)

Question 2

What is glutamate dehydrogenase (GLDH) an indicator of and is it specific?

Answer 2

Hepatocellular damage.

Liver specific.

Question 3

What is sorbitol dehydrogenase (SDH) an indicator of and how useful is it?

Answer 3

Indicator of hepatocellular injury. It is unstable in vitro - impractical to measure unless a lab is close by. However, it is liver specific which is helpful in horses and ruminants.

Question 4

What is Aspartate Aminotransferase (AST) an indicator of and how specific is it?

Answer 4

Indicator of hepatocellular injury.

Is not specific - found in liver and in muscle. Also in erythrocytes.

Question 5

What is Alanine Aminotransferase (ALT) an indicator of and is it specific?

Answer 5

Hepatocellular injury.

Not specific - small amounts in muscle.

Question 6

In which animals in measurement of ALT not useful?

Answer 6

Horses and ruminants - little ALT in hepatocytes.

Question 7

Where does intra-hepatic cholestasis occur and what may cause it?

Answer 7

Within the bile canaliculi and bile ducts within the liver.

Caused by processes that cause significant hepatocytes swelling (lipidosis, glycogen deposition, inflammation)

Question 8

Where does extra-hepatic cholestasis occur and what can cause it?

Answer 8

Outside the liver - gall bladder or common bile duct.

Caused by a physical obstruction of bile flow (inflammation, infection, cholethiasis, neoplasia)

Question 9

Retention of bile with cholestasis increases serum concentrations of what?

Answer 9

Bilirubin and bile acids.

The enzymes GGT and ALP.

Question 10

Increased serum Alkaline phosphatase (ALP) may be associated with many things, including:

Answer 10

Cholestasis, bone lysis/remodelling, corticosteroid treatment, colic in horses, hyperthyroidism in cats

Question 11

Increased activity of gama glutamyl transferase (GGT) in serum can indicate:

Answer 11

Cholestasis
Severe hepatic necrosis in horses/cattle

Induced by steroids in dogs

Question 12

Which enzymes is the best indicator of cholestasis?

Answer 12

Gama glutamyl transferase (GGT)

Question 13

Which enzymes are released from damaged hepatocytes?

Answer 13

Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Sorbitol dehydrogenase (SDH) 
Glutamate dehydrogenase (GLDH)

Question 14

What is bilirubin?

Answer 14

Pigment produced by the breakdown of the heme portion of haemoglobin by macrophages

Question 15

What is the difference between hyperbilirubinaemia and icterus?

Answer 15

Hyperbilirubinaemia is increased bilirubin in the blood.

Icterus is increased bilirubin in tissue.

Question 16

What causes pre-hepatic hyperbilirubinaemia?

Answer 16

Increased red blood cell breakdown (haemolysis)

Question 17

What are the hepatic causes of hyperbilirubinaemia?

Answer 17

Decreased hepatic uptake/conjugation (decreased functional mass)
Functional cholestasis
Anorexia/fasting (horses and cats)

Question 18

What causes post-hepatic bilirubinaemia?

Answer 18

Extra-hepatic disruption of bile flow causing partial/complete blockage.

Question 19

Is trace bilirubinuria normal?

Answer 19

Normal in dogs with concentrated urine.

Always significant in cats and reflects hyperbilirubinaemia.

Question 20

What are bile acids synthesised from?

Answer 20

Cholesterol

Question 21

When do you measure bile acids in small animals?

Answer 21

Measure when fasted and then 2hrs after a meal.

Question 22

Is measurement of bile acids useful in large animals?

Answer 22

Horses lack a gall bladder - fairly random bile acid concentration but will see marked increase with hepatobiliary disease.
Cattle have extremely variable serum bile acid concentration.

Question 23

What is important to remember when testing for ammonia?

Answer 23

Sample should be collected into a heparinised tube and plasma should be separated immediately and analysed.

Question 24

What are the causes of increased ammonia?

Answer 24

Physiological (high protein meals, extreme exercise)
Disease (hepatic insufficiency, toxicities, inherited disorder in urea cycle)
GI lesions in horses
Lack of urea cycle intermediates (arginine def. in cats)

Question 25

Which tests are affected by alterations in hepatic synthesis?

Answer 25

``` Glucose Albumin Urea Cholesterol Vit K dependant clotting factors ```

Question 26

What might increased amylase indicate?

Answer 26

Pancreatitis, renal disease

Question 27

What might increased lipase indicate?

Answer 27

Pancreatitis, renal disease, GI disease

Question 28

Which cells is gama glutamyl transferase associated with?

Answer 28

Brush border / microvilli of hepatocytes, billiary epithelial cells, renal tubular epithelial cells. Also mammary secretions.