Hepatobiliary - bile salts and ammonia Flashcards
What AA does cholesterol conjugate with in dogs and cats? Humans?
Dogs and cats – taurine
Humans – glycine
What are most reference values based off of?
12 hour fast
What is more sensitive, fasting or post-prandial testing?
Post prandial
When is a post prandial sample taken?
2 hours
What should we feed the animals we are doing a bile acids test? Why?
Science A/D
1-2 tsp for animals < 10lb
1-2 tbsp for animals > 10lb
Provides uniform gall bladder stimulation, GI motility
What would cause a pre prandial value to be higher than a post prandial bile acid value?
Unexpected gall bladder contraction: maybe the animal smelled food being prepared
What kind of sample should be taken for a bile salts assay?
serum
For what assay do you need to specify taurine measurement?
Radioimmuno assay
What type of assay measures total bile salts?
Spectrophotometry
What interferes with bile acid tests and ammonia tests?
lipemia and hemolysis
What are three ways we can test bile acids?
Fasting
Fasting + post prandial
Post prandial
Why would fasting + post prandial provide greater sensitivity?
some affected animals with have normal resting levels.
Why would we do a bile acids test? Is this a specific test?
Confirm suspicion of decreased functional mass of the liver
NOT specific for decreased functional mass!
What are bile acid salts sensitive for?
Hepatobiliary disease
NOT specific for various types though!
What are some conditions that may give abnormal results for bile acids and give you a reason NOT to use bile acid test?
Evidence for significant cholestasis
Evidence for significant hepatocellular injury
+/- significant GI dz
What are some aberrant patterns/atypical findings for bile acids?
- poor reabsorption of BA may cause suppress resting BA in animals that should have increase
- Post BA </= fasted value – test is not of diagnostic value (retest!)
- Hemolysis is a negative interferent in the assay
What does post-BA > or equal to fasted value suggest?
- spontaneous gall bladder contraction
2. poor CCK response (didn’t eat food, other)
What are three additional dx modalities you can use to differentiate b/w shunt and hepatic insufficiency? These are follow ups taken for both bile acids and ammonia
- Aspiration cytology and/or biopsy
- Imaging
- Surgery
Why would we do an ammonia or ammonia tolerance test?
confirm presence of decreased functional mass
What tow types of conditions present as decreased functional mass?
- reduced liver parenchyma
2. vascular shunts
What are 3 sample handling considerations for ammonia testing?
- blood must be drawn into ammonia free heparin
- blood must be put on ice immediately
- plasma must be separated from the RBC within 20 minutes
When should the ammonia sample be run by?
within 30 minutes (60 max)
if quick frozen – run within 2 days
When should you run resting ammonia levels first, before running ATT?
- debilitated animals
- those showing CNS symptoms
DO NOT run ATT if resting levels are high!!!
When can you run resting ammonia levels at the same time as ATT?
clinical symptoms are not severe
