Liver and Pancreas Clin Path

Question 1

what 2 things are necessary to globally determine liver health?

Answer 1

both hepatic enzymes AND indicators of liver function!!!

Question 2

what are the 2 types of hepatic enzymes?

Answer 2

1. those that indicate hepatocellular damage
2. those that indicate cholestasis

Question 3

what is cholestasis?

Answer 3

interruption or obstruction of bile flow or excretion, with the slow flow of bile, enzymes have time to chew on hepatocytes, so cause those hepatocytes to slough off into blood, taking the enzyme with them and increasing that enzyme level in blood

Question 4

describe hepatic enzymes that indicate liver damage (3) and give 3 examples

Answer 4

1. released with hepatocyte damage or necrosis
2. blood increases can be seen just hours after injury or damage
3. many species differences between species so panels vary

examples are: ALT, AST, SDH

Question 5

describe cholestatic enzymes (4) and give 2 examples

Answer 5

1. membrane bound
2. cholestatic enzymes are not the best name for these enzymes because other things can cause increases in these enzymes as well
3. increases in levels of these enzymes in blood take days, not hours
4. again, species differences so panels vary

examples are: ALP and GGT

Question 6

describe ALP (what is stands for and the sources)

Answer 6

1. stands for alkaline phosphatase
2. total ALP is comprised of sources from liver (the top contributor), bone, and also corticosteroid induced in dogs

Question 7

what do blood increases in ALP indicate? (3, plus a 4th for dogs only)

Answer 7

1. cholestasis
2. bone remodeling in young growing animals since panel values have reference intervals for adults
3. animal hit by car or with a bone tumor could also be a reason for bone remodeling
4. induction by steroidal drugs in dogs only!

Question 8

what could a blood increase in GGT indicate? what does GGT stand for?

Answer 8

GGT = gamma glutamyl transferase
1. cholestasis
2. steroids (dogs only and is minimal so not worth investigating
3. colostrum ingestion in DOGS, SHEEP, and CATTLE (neonates, 7-10 days old); NOT cats or horses so if see elevated GGT in kittens or foals, investigate!!

Question 9

do increases in liver enzymes indicated a loss of function? how is it best to measure these enzymes?

Answer 9

nope! remember, must evaluate both enzymes AND liver function!! and serial measurements are much more helpful to understand the full picture

Question 10

what kind of substances are indicators of liver function? (2)

Answer 10

substances that are
1. synthesized by the liver or
2. removed from the blood by the liver

Question 11

when are changes in the substances that indicate liver functions typically seen?

Answer 11

not until 60-70% of the functional liver mass is gone (AKA: liver is fucked)

Question 12

list the substances (5) and the change in the substance observed on a liver panel if liver function is compromised

Answer 12

1. albumin: decrease
2. cholesterol: decrease
3. urea nitrogen (BUN): decrease
4. glucose: decrease
5. bilirubin: INCREASE

Question 13

what is a systemic change observed if liver function is compromised?

Answer 13

decreased production in coagulation factors

Question 14

how does albumin reflect normal liver physiology?

Answer 14

all albumin is synthesized in the liver, so loss of 60-80% liver function leads to hypoalbuminemia

Question 15

how does urea nitrogen indicate liver function? (BUN)

Answer 15

hepatocytes convert ammonium to urea, so if there is liver dysfunction there is less synthesis of urea

Question 16

how does cholesterol indicate liver function? give exception with cholestasis

Answer 16

liver synthesizes cholesterol so liver dysfunction = lower cholesterol, but cholestasis blocks clearance of cholesterol and actually causes cholesterol to increase

Question 17

how does glucose indicate liver function?

Answer 17

the liver is important for gluconeogenesis, so decreased liver function would lead to a decrease in glucose, BUT more than 75% of liver mass must be lost before hypoglocemia occurs as it is one of the last changes to appear since glucose is so vital to the body

Question 18

how does bilirubin indicate liver function?

Answer 18

bilirubin is a pigment produced by the degradation of heme, which occurs in the liver, and total bilirubin is comprised of unconjugated and conjugated bilirubin

Question 19

give the 3 types of hyperbilirubinemia and their causes

Answer 19

hyperbilirubinemia can be pre-hepatic (due to increased hemolysis)

hepatic (due to anorexia in horses and cattle, decreased functional liver mass, or intrahepatic blockages)

or post-hepatic (due to decreased secretion into biliary system or post-hepatic cholestasis/pancreatic disease)

Question 20

describe how evaluation of serum bile acid and ammonia levels reflect the health of the liver and enterohepatic circulation

Answer 20

bile acid: the liver makes bile acids, which are then secreted into bile and transported to the duodenum, most are then reabsorbed into portal blood or excreted via feces; so normally there will be a peak in bile acids post meal that will return to healthy levels in 2+ hours, but liver dysfunction will lead to prolonged blood increases in bile acids (this test can be affected by cholestasis, spontaneous gall bladder contraction pre-sample, and concurrent intestinal disease)

ammonium: derived from dietary proteins; decreased clearance of ammonia due to liver damage, leading to hyperammonemia; not affected by cholestasis but the drawback is the sample must stay on ice and be processed super quickly so if live far from lab, will not be able to run this test

Question 21

identify how amylase is used to assess exocrine pancreatic health

Answer 21

amylase: can come from the pancreas, or from small intestine, liver, and even salivary ducts in pigs and humans (multiple sources = less accurate picture of pancreatic health); cleared by kidneys majorly and some by the liver (clearance by other organs also affects picture of pancreatic health)

increase amylase could indicate (3):
1. pancreatic acinar cell damage due to inflammation or neoplasia
2. decreased clearance due to decreased glomerular filtration rate or liver disease
3. intestinal disease/obstruction

decreased amylase is not clinically significant

Question 22

identify how lipase is used to assess exocrine pancreatic health

Answer 22

lipase is produced by the pancreas but also by the stomach, liver, and endothelium (hard to determine pancreatic health due to multiple sources) and cleared by the kidneys (clearance by other organs also means hard to use to assess pancreatic function)

increased lipase could indicate (3):
1. pancreatic acinar cell damage due to inflammation or neoplasia
2. decreased clearance due to decreased glomerular filtration rate
3. corticosteroids: in dogs

decrease lipase is often an artifactual finding

Question 23

describe how pancreatic lipase immunoreactivity indicates exocrine pancreatic health

Answer 23

this is an immunoassay that determines that concentration of pancreatic lipase, not the enzymatic activity, so the pancreas is the only source being evaluated and a much more specific test that is not affected by renal function or corticosteroids in dogs!!

increased PLI is indicative of pancreatitis when correlated with clinical signs and imaging

decreased PLI is associated with reduced functional pancreatic acinar tissue mass, as a result of chronic pancreatitis or exocrine pancreatic insufficiency (there is a better test for EPI though hold please)

Question 24

how is trypsin-like immunoreactivity indicative of exocrine pancreatic health?

Answer 24

measures trypsin and trypsinogen concentration, where the pancreas is the predominant source, so is the test of choice to diagnose exocrine pancreatic insufficiency!

however, trypsin is cleared by the kidney so renal function could affect this test

increased TLI is indicative of (3)
1. pancreatitis (inconsistent bc renal interference)
2. decreased glomerular filtration rate
3. postprandial (after a meal, animal ate recently)

decreased TLI could indicate:
1. maldigestion/malabsorption due to exocrine pancreatic insufficiency!! or intestinal disease
2. decreased release from pancreatic cells due to chronic pancreatitis or pancreatic acinar atrophy

Question 25

how is the endocrine pancreatic health evaluated?

Answer 25

hyperglycemia can indicated transient acute pancreatitis; pancreas plays a role in glucose homeostasis