Laboratory diagnostics of liver disease

Question 1

What are the enzymes that indicate liver damage?

Answer 1

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

Question 2

Which liver enzymes are used in small and large animals?

Answer 2

ALT - dogs and cats

LA have low hepatic ALT so use SDH and GLDH instead

Question 3

How can liver damage vs. muscle damage be distinguished when AST is high?

Answer 3

Check creatine kinase which will be increased 1-2 hours after muscle injury but will decrease over the next 24-48 hours so if it is persistently elevated then it indicates the increase ALT/AST are from muscle.

Question 4

Which enzymes indicate cholestasis?

Answer 4

Alkaline phosphatase (ALP)
Gammaglutamyl transferase (GGT)

Question 5

What is the significance of increase ALP in:

a) dogs
b) cats

Answer 5

a) may be due to iatrogenic steroids or stressed animal

b) always significant

Question 6

If GGT is found in urine of LAs what does this indicate?

Answer 6

Renal tubular cell damage

Question 7

What is the significance of bilirubinuria in a:

a) dog
b) cat

Answer 7

a) normal if low levels in dog

b) significant finding in cats

Question 8

What does decreased urea + increased ammonia indicate?

Answer 8

Hepatic disease - as ammonia not being converted to urea

Question 9

What is the significance of fluctuations in cholesterol for liver pathology?

Answer 9

It normally fits a pattern but is not diagnositic.

Increases - cholestasis as decreased excretion
Decreases - hepatic failure due to decreased synthesis