Hepatic, intestinal and pancreatic function

Question 1

what can be tested for relating to the liver?

Answer 1

hepatocellular injury
cholestasis
hepatocellular function
hepatic portal circulation

Question 2

what is hepatocellular injury and how is it tested?

Answer 2

damage to hepatocytes leading to enzyme leakage

Question 3

what is cholestasis and how is it tested for?

Answer 3

reduced/blocked bile excretion leading to enzyme release through pressure being exerted onto cells

Question 4

what is actually being measured when looking for liver enzymes?

Answer 4

activity of enzyme (rather than the concentration)

Question 5

what are the liver “leakage” enzymes?

Answer 5

ALT, AST, LDH, SDH, GLDH

Question 6

what is a liver “leakage” enzyme?

Answer 6

enzymes that can be found in blood after hepatocellular damage or death

Question 7

is ALT liver specific?

Answer 7

largely liver specific but also found in muscle

Question 8

is AST liver specific?

Answer 8

no, found in liver and muscle

Question 9

is LDH liver specific?

Answer 9

no, found in liver and muscle

Question 10

is SDH liver specific?

Answer 10

yes

Question 11

is GLDH liver specific?

Answer 11

yes

Question 12

what does increased liver enzymes suggest?

Answer 12

hepatocellular damage

Question 13

what does the magnitude of increase in liver “leakage” enzymes correlate to?

Answer 13

degree of hepatocellular damage

Question 14

why are even small increases in liver “leakage” enzymes in cats significant?

Answer 14

they have a very short half life (hours)

Question 15

what enzymes are released due to cholestasis?

Answer 15

ALP and GGT

Question 16

what is ALT?

Answer 16

alanine aminotransferase

Question 17

what is AST?

Answer 17

aspartate aminotransferase

Question 18

what is LDH?

Answer 18

lactic dehydrogenase

Question 19

what are the main liver leakage enzymes used in small animals?

Answer 19

ALT and AST

Question 20

other than hepatocellular damage what can cause increased liver “leakage” enzymes?

Answer 20

myocyte damage can cause mild increase of AST and LDH
haemolysis can increase AST and LDH

Question 21

what can be used to validate whether raised AST/LDH is due to muscle damage?

Answer 21

creatinine kinase (increased would indicate myocyte damage)

Question 22

does magnitude of liver “leakage” enzymes correlate with prognosis?

Answer 22

no - magnitude of enzymes only correlates with degree of damage

Question 23

what are the cholestatic enzymes?

Answer 23

ALP and GGT

Question 24

where are cholestatic enzymes found?

Answer 24

on the cell membrane (pressure from cholestasis causes them to fall off)

Question 25

what is ALP?

Answer 25

alkaline phosphatase

Question 26

what can increase ALP other than cholestasis?

Answer 26

corticosteroids or phenobarbital Scottish terriers predisposed to vacuolar hepatopathy and hence higher ALP

Question 27

what is the most specific enzyme marker for cholestasis?

Answer 27

GGT

Question 28

what bile components can increase due to cholestasis?

Answer 28

bilirubin bile salts cholesterol

Question 29

what are the two isoenzymes of ALP?

Answer 29

intestinal and non-tissue specific

Question 30

where does unconjugated bilirubin come from?

Answer 30

breakdown of RBCs

Question 31

where does bilirubin become conjugated?

Answer 31

liver

Question 32

what are the types of hyperbilirubinaemia?

Answer 32

pre-hepatic hepatic post-hepatic

Question 33

what causes pre-heptic hyperbilirubinaemia?

Answer 33

haemolysis (check anaemia)

Question 34

what causes hepatic hyperbilirubinaemia?

Answer 34

decreased bilirubin uptake, conjugation or excretion (hepatocyte dysfunction)

Question 35

what causes post-hepatic hyperbilirubinaemia?

Answer 35

obstruction of extra hepatic bile ducts

Question 36

what forms can bilirubin be measured directly as?

Answer 36

total or conjugated

Question 37

what form of bilirubin can't be measured directly?

Answer 37

unconjugated (total minus conjugated)

Question 38

what are some clinical signs of hyperbilirubinaemia?

Answer 38

jaundice (icterus)

Question 39

why can jaundice persist even after the livers function returns to normal?

Answer 39

some bilirubin binds to albumin (delta-albumin) which persists in circulation

Question 40

how can you determine if jaundice is due to delta-albumin or not?

Answer 40

if it is due to delta-bilirubin there will be no biliruburia

Question 41

what are the functions of the liver?

Answer 41

detoxification cholesterol and bile acid synthesis plasma protein synthesis RBC breakdown carbohydrate, lipid and amino acid metabolism removal of bacteria clotting factor production glycogen, iron, copper, vitamin storage

Question 42

what ways can we test for hepatocellular function?

Answer 42

decreased uptake/excretion of bilirubin and blue acids decreased conversion of ammonia to urea decreased synthesis of metabolites decreased synthesis of coagulation proteins decreased immunologic function

Question 43

what metabolites of the liver will decrease if hepatocellular function is impaired?

Answer 43

albumin, cholesterol, coagulation factors, glucose

Question 44

what is the main coagulation protein tested for in cases of suspected decreased hepatocellar function?

Answer 44

fibrinogen

Question 45

if blood supply to the liver is decreased (portosystemic shunts) what changes can be tested for?

Answer 45

decreased uptake/excretion of bile acids decreased conversion of ammonia to urea decreased immunologic function

Question 46

where is ammonia produced?

Answer 46

by protein digestion of bacteria metabolism in the gastrointestinal tract

Question 47

how is ammonia metabolised?

Answer 47

enters the liver via the portal vein and is taken up by hepatocytes to synthesise urea, amino acids and proteins

Question 48

how are bile acids metabolised?

Answer 48

bile salts are produced by hepatocytes and released into the biliary system and then the intestines to allow fat absorption/digestion

Question 49

what happens to the majority of bile salts released into the intestine?

Answer 49

reabsorbed from the ileum into the portal vein and return to the liver (rest is lost in faeces)

Question 50

why may bile acids be increased?

Answer 50

reduced uptake/excretion by hepatocytes disruption of enterohepatic circulation (shunts/cholestasis) reactive hepatopathies

Question 51

what values of fasting serum bile acids indicate hepatobiliary pathology?

Answer 51

>25-30 mmol/L

Question 52

how are post prandial serum bile acids (bile acid stimualtion) tests carried out?

Answer 52

take resting serum bile acid feed animal a fatty meal sample 2 hours after feeding

Question 53

what are some possible extra hepatic diseases that lead to elevated liver enzymes?

Answer 53

hypoxia GI and pancreatic disease endocrine diseases sepsis

Question 54

what are extrahepatic disease that cause elevated liver enzymes sometimes referred to as?

Answer 54

reactive hepatopathies

Question 55

how are bile acid levels effected by reactive hepatopathies?

Answer 55

usually normal or mildly elevated

Question 56

what are some abnormalities that may be seen on haematology of liver disease cases?

Answer 56

microcytosis in portosytemic shunts or severe liver insufficiency due to altered iron transport/metabolism) ovalocytes in cats with hepatic lipidosis acanthocytes due to disruption of normal vasculature

Question 57

what may be seen on urinalysis of liver disease cases?

Answer 57

isothenuria or low USG bilirubinaemia ammonium biurate crystals or uroliths (portosystemic shunts)