liver function 2: liver enzymes

Question 1

causes of increased ammonia in the blood

Answer 1

• impaired liver function
  
  • decreased urea production
  • peracute liver failure
  • liver cirrhosis or neoplasia
  • PSS
  • hepatic lipidosis
  • lipid mobilisation disease
• Ruminal alkalosis
• intestinal disbacteriosis of ammonia producing bacteria (mainly Ru/Eq)
• cogenital enzomopathies

Question 2

liver cell enzymes used in diagnostics

Answer 2

• AST (aspartate - aminotransferase)
• ALT (Alanine - amino transferase)
• GLDH ( glutamate - dehydrogenase)

Question 3

describe AST

Answer 3

• Location
  
  • mitochondria of liver cells
  • liver specific in herbivores
  • muscles and RBCs (false positive)

Question 4

causes of increased AST activity

Answer 4

• from muscle cells
  
  • intense excercise
  • training
  • muscle necrosis
  • muscle inflammation
  • muscle injury
  • myocarditis
  • neoplasm or muscle cells
• from the liver cells
  
  • ethanol consumption
  • hepatopathy (in herbivores)
  • severe parenchymal damage
    
    • in Ca: lipotic degradation, hepatitis, toxic liver damage
  • Copper syndrome
• From the RBCs
  
  • Haemolysis

Question 5

Describe ALT

Answer 5

• routine enzyme for cats and dogs
• liver specific in cats and dogs
• not liver specific in herbivores
• found in cytoplasm (less severe cell damage may cause increased activity)

Question 6

causes of increased activity of ALT

Answer 6

• Produced in the event of liver damage
  
  • chronic active hepatitis (CAH), cholangiohepatitis (CH)
    
    • viral hepatitis
    • hepatic lipidosis
  • cirrhosis
  • bile duct obstruction
  • liver neoplasm (AST/ALT)
• pancreatitis
• septicaemia
• neoplasm
• drugs
  
  • salicylates
  • barbiturates
  • glucocorticoids
  • as a result of cell damage
• copper storage disorder
  
  • west highland terriers
  • dobermand
  • bedlington terriers

Question 7

Describe GLDH

Answer 7

• usually used in herbivores
• liver specific
• small amount found in nerves and muscles (mitochondria only)

Question 8

causes of increased GLDH

Answer 8

severe liver necrosis that leads to mitochondrial membrane damage

Question 9

Name the bile duct obstruction enzymes?

Answer 9

AKLP (Alkaline phosphatase)

GGT (gamma glutamyl - transferase)

Question 10

describe ALKP

Answer 10

• potentially appears in every cell membrane
• only hepatic and bone ALKP appears in the blood
• not liver specific in cats
• tubular cell damage causes increase in activity

Question 11

causes of increased activity of ALKP

Answer 11

• Bone originated
  
  • young dogs (> 8 months)
  • newborn animals
  • pregnant animals
  • bone tumours
  • osteomyelitis
  • bone fractures
  • healing of fractures (callus formation)
  • paraneoplastic processes
    
    • lumphoid, lung and hepatic tumours
• liver originated
  
  • cholestasis
  • Bile acids ( increased ALKP synthesis, helps liberate it from membranes)
  • acute hepatic necrosis
  • liver cirrhosis
  • intra-, extra hepatic biliary obstruction
  • cholangitis
  • hepatic lipidosis - in cats
  • Barbiturates (Increase ALKP synthesis)
  • Salicilates
• In connection with SIAP
  
  • hyperadrenocorticism
  • nitrogenous or endrogenous (cushing’s)
  • chronic stress
• activity will decease in very severe cirrhosis

Question 12

describe GGT

Answer 12

• produced in different organs
• endothelial cells of the bile duct concentrate it
• GGT of the liver origin appear in the blood
• liver specific in horses and cats

Question 13

causes of increased GGT activity

Answer 13

• biliary stasis
• cholangiohepatitis
• cirrhosis
• neoplasm
  
  • hepatic
  • pancreatic
• hepatic lipidosis
• barbiturates
• ethanol specifically exaggerates GGT in humans