Chapter 12 Flashcards
What is a possible cause of liver enzyme elevation in the absence of functional and histopathological change?
Macroenzyme formation - large antibody-bound complexes of enzymes, slowly cleared from the circulation
ALT - location in cell?
Cytosolic
What is the liver enzyme of choice for hepatocellular damage?
ALT
Where is ALT found?
Liver
(Heart, kidney, muscle)
What drugs can be associated with ALT elevation?
Phenobarbital, doxycycline, methimazole/carbimazole, prednisolone, azathioprine, ketoconazole, sulphonamides, paracetamol
AST - location in cell?
Hepatocellular - cytosol and mitochondria
Where is AST found?
Liver, cardiac and skeletal muscle
What may an advantage of AST over ALT measurement?
Because AST is mitochondrial bound as well as in the cytoplasm, AST elevation may indicate more severe liver injury. Also shorter half life - suggests persistent liver injury
Less likely to be increased in secondary hepatopathies
ALKP - location in cell?
Microsomal and biliary canalicular membranes
What is the difference between ALKP in dogs and cats?
Cats have no steroid-induced isoenzymes
What ALKP isoenzymes exist?
Bone
(Intestine)
(Kidney)
Placenta
What causes ALP elevation in cholestasis?
Regurgitation from within hepatocytes
Solubilisation of ALKP from membranes by accumulation of bile salts
De novo synthesis
Where is GGT found?
Liver, kidney, pancreas, intestine, heart, lungs, muscle, RBCs, milk
In dogs, how do the sensitivities and specificities of ALKP and GGT compare?
GGT more specific but less sensitive
In cats, how do the sensitivities and specificities of ALKP and GGT compare?
ALKP more specific but less sensitive
What SPE changes would be expected in severe liver disease?
Reduction in all except gamma globulins (not produced in liver)
Albumin most affected
What is the half life of albumin in dogs?
1-3 weeks
How is bilirubin produced and processed?
pg 246
What is deltabilirubin?
Biliprotein - bilirubin covalently bound to albumin
Turnover same speed as albumin
How can abdominal fluid analysis determine the cause of ascites in liver disease?
Transudate - hypoalbuminaemia or pre hepatic portal hypertension
Modified transudate - hepatic or pre hepatic portal hypertension (hepatic sinusoids highly permeable - hepatic lymph contains 80% serum proteins)
What are bile acids formed from?
Cholesterol and taurine
Where are bile acids absorbed?
Ileum
Describe bile acid processing
Pg 250
How high can secondary hepatopathies increase SBA by?
Often up to 50, occasionally up to 100
What could cause elevated ammonia and normal BAST?
Abnormal urea cycle
Cobalamin deficiency
What is the reported sensitivity and specificity for PSS diagnosis of a) BAST and b) ammonia?
a) D - 93/67%
C - 100/71%
b) D - 85/86%
C - 83/76%
