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
