Approach to incidental liver enzyme elevation Flashcards
What are the markers of hepatocellular injury?
ALT, AST
-increase due to hepatocellular necrosis or degeneration (the more cells damaged, the higher the ALT)
-half-life of ALT is 2.5 days in dogs and even shorter in cats meaning that persistent increases means continued damage to the liver cells
What are the markers of cholestasis/enzyme induction?
ALP, GGT
- induced with decreased bile flow (cholestasis)
- ALP isoenzymes can be produced by liver, induced by corticosteroids (common in dogs- cushings), or induced through the breakdown of bone (only common in young growing dogs)
-half-life of 70 hrs in dogs, 6 hrs in cats
-induced by phenobarbital
What are the markers of impaired liver function?
Bilirubin, albumin, glucose, cholesterol, BUN
-bilirubin also increases with hemolysis and bile tract disease
-albumin is made exclusively in liver, so low albumin indicates liver dysfunction as long as loss through kidneys or GI tract has been ruled out
-glucose becomes decreased when there is >75% liver function lost
-cholesterol can be very variable
-BUN can decrease from portosystemic shunts or chronic liver disease, but must also rule out low dietary protein or starvation
T/F: cats with hepatic lipidosis typically have ALP quite high and GGT normal or only slightly elevated
True
T/F: elevated ALP is a negative prognostic indicator in cases of osteosarcoma
True- indicates a lot of bone lysis
Why are prolonged clotting times (PT/PTT) potentially an indicator of significant hepatic disease or factor consumption?
The liver produces most clotting factors
When should you perform a bile acids test?
-it is the most sensitive liver function test readily available for use in small animals
-indicated for screening for loss of hepatic function or PSS
-DO NOT USE IF HYPERBILIRUBINEMIC (wont be accurate)
->25-30% is abnormal, if >50% more likely to be PSS
-best for patients with incidental liver enzyme elevations, wont help us with patients with obvious liver dysfunction (these need ultrasounds/biopsies)
What is the next step in a case where elevated liver enzymes are seen?
Rule out other causes:
- drug or toxin (NSAIDS-specifically carprofen, acetaminophen, anticonvulsants, CBD and other supplements, antifungals, TMS, azathioprine, and methimazole)
-endocrine disorders (diabetes mellitus, hypothyroidism, hyperthyroidism, hyperadrenocorticism)
-dental disease
-GI disease (IBD, pancreatitis)
-metastatic neoplasia
-nutritional abnormalities (raw diet)
-cardiovascular disease (hypoxia, hypotension)
-sepsis/infection
T/F: it is ok to wait and monitor if there is an incidental liver enzyme elevation on BW
true, just be sure owners know to what for watch for
- although non-clinical patients should have a recheck bloodwork prior to doing expensive or invasive testing
What breed is liver toxicity due to carprofen most common in?
Labradors
When should you investigate incidental liver enzyme elevations further?
-ALT greater than twice normal over several months
-unexplained liver enzyme elevations persisting over 6-8 weeks
-non-hepatic causes have been ruled out
What breeds are the most predisposed to copper associated hepatopathy?
Dobermans, cocker spaniels, english springer spaniels, westies
What breeds are the most predisposed to portal vein hypoplasia?
-cairn terriers, yorkies, papillons, toy poodles
What is one of the most common causes of incidental increased liver enzymes in older dogs?
Vacuolar hepatopathy
What breeds are the most predisposed to chronic hepatitis?
Labs, cocker spaniels, dobermans, west highland terriers
