Lecture 13 Laboratory evaluation of the liver

Question 1

what are the most common hepatic function tests?

Answer 1

billirubin,
bile acida,
ammonia

Question 2

what are the two main types of bilirubin?

Answer 2

unconjugated (indirect)
bilirubin that is escorted to the liver by proteins like albumin as it is other wise insoluble;

conjugated (direct)
in the liver, it is conjugated to glucuronide (and glucose in horses) and is then water soluble. It is transported by another saturable protein into the bile, some escapes into the blood and is excreted into the urine (urobilinogen)

Question 3

what form of bilirubin is transported into bile

Answer 3

Conjugated

Question 4

what form of bilirubin at times will escape into the urine? and what is that term?

Answer 4

conjugated bilirubin,

urobilinogen

Question 5

define hyperbilirubinemia, its cause, and what are the 3 forms

Answer 5

Increased levels of bilirubin, the rate of bilirubin production exceeds the rate of uptake by hepatocytes, rate or conjugation, or rate of excretion.

Pre-hepatic,
increased destruction of erythrocytes,
Hepatic,
decreased uptake of bilirubin by hepatocytes ,
Post-hepatic,
impaired bile flow

Question 6

why would you see bilirubin in the urine before the plasma?

Answer 6

this is due the the low threshold in the kidneys

Question 7

T or F

bilirubinuria found on a urinalysis in a cat is ok in small amounts

Answer 7

FALSE

any amount of bilirubin excreted in a cat is a red flag

Question 8

if your patient is icteric at presentation and you are concerned about liver function would you measure bile acids? why or why not?

Answer 8

No

it is a waste of time and money, the patient is already icteric, the bile acids are already up.

Question 9

why does a blood ammonia test need to be preformed within 30 min of collection?

Answer 9

the production of protein and amino acid metabolism continues which causes ammonia to continually leak from the erythrocytes causing artificially increased values.
Keeping the sample on ice will help keep those values closer to actual numbers

Question 10

what is a congenital Dz that puppy’s can get where you might need to utilize a blood ammonia test, when you suspect they might be hyperammonemic?

Answer 10

Portosystemic shunt

Question 11

if your worried about liver failure, what test would be lower?

Answer 11

Colesterol
Albumin
Urea (BUN)
Glucose

Question 12

if you suspect that your patient is in liver failure, and you need a biposy, what test might you consider running before taking your sample?

Answer 12

coagulation test to ensure that that they can form clots correctly. The liver is responsible for many factors needed for homeostasis, it is likely that they are affected and may be low.

Question 13

In the wake of liver failure, what RBC morphology might you see on a blood smear

Answer 13

Acanthoctes
target cells (codocytes)
microcytosis

Question 14

In the wake of liver failure, what might you see on a urinalysis?

Answer 14

Bilirubinuria

bilirubin crystals

Question 15

why is ascites a feature of liver failure

Answer 15

the liver is responsible for the production on many of the proteins that circulate within the plasma (mainly alb), with hypoprotenemia fluid will escape from the vasculature causing ascites.