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59 Cards in this Set
- Front
- Back
What does a measurement of an enzyme indicate?
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Its activity, not quantity present
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What are enzyme tests called?
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Kinetic assays
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Where in the body do enzymes normally not function?
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Blood stream
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5 reasons for increased enzyme levels
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- Increased release from damaged cells
- Increased synthesis - Increased levels from hyperplastic or neoplastic cells - Decreased enzyme clearance - Increased from ingestion or absorbance (such as passive transfer) |
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Diagnostic value of enzyme levels in blood that are below reference intervals
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No diagnostic value since it's not associated with a defined pathology
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What fold elevation cut off is most clinically relevant?
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> 3 fold increase
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Pre-hepatic factor that affects liver tests
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Anemia
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Hepatic factor that affects liver tests
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Primary liver disease
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Post-hepatic factor that affects liver tests
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Gall bladder or bile duct issues
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What is there a correlation between in terms of concentration of enzymes released from the liver?
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Amount of hepatic cells damaged
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How much of the liver must be damaged for hepatic insufficiency?
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70 - 80%
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5 substances that are reduced in hepatic insufficiency
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- Glucose
- Albumin - Urea - Coagulation factors - Cholesterol |
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2 species that ALT is indicative of liver damage in
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- Cats
- Dogs |
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4 hepatocellular enzymes
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- ALT
- AST - GLD - SDH |
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2 extrahepatocellular enzymes
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- ALP
- GGT |
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Two liver values used to assess hepatic injury in large animals
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- AST
- SDH |
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What species has a unique ALP, and what induces it?
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Canine
- Induced by Corticosteroids |
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What type of ALP do most instruments measure?
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No specific one, just total ALP in general
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6 causes for ALP elevation
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- Cholestasis
- Phenobarbitol - Young, growing animals - Osteosarcoma - Mammary neoplasms (dogs only) - Corticosteroids |
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How long does it take after administration of corticosteroids in dogs for ALP levels to rise?
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One week
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What does a rise in ALP indicate in cats? (2)
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- Cholestasis
- Decreased enzyme clearance |
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3 common causes of increased ALP levels in cats
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- Cholestasis
- Decreased enzyme clearance - Hyperthyroidism |
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What is the most common cause of increased ALP levels in cats?
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Hepatic lipidosis
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What is GGT primarily associated with?
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The membranes of biliary epithelial cells
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What will increase urine GGT but not blood GGT?
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Renal tubular damage
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Two good indicators of cholestasis in dogs and cats
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- GGT
- ALP |
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5 causes of increased GGT in cats
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- Cholangiohepatitis
- Cholangitis - Bile duct obstruction - Hepatic lipidosis - Hepatic neoplasia |
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What's best for detecting cholestasis in cattle and horses?
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GGT
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Two things GGT is used to assess in large animals
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- Hepatic damage
- Cholestasis |
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What transports billirubin to the liver?
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Albumin
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Source of billirubin
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By-product of hemoglobin break down and conversion from heme
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Two methods of conjugated bilirubin elimination
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- Bile
- Urine |
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At what level of billirubinemia does the plasma become icteric?
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> 1.5 mg/dl
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At what level of billirubinemia do the tissues become icteric?
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> 2 - 3 mg/dl
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What precedes bilirubinemia in dogs and why?
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Bilirubinuria
- Has bilirubin conjugation ability in kidneys |
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What bilirubin form increases due to severe hemolysis?
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Unconjugated
- Conjugated can increase too with chronicity |
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Prehepatic cause for hyperbilirubinemia
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Hemolysis
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Hepatic cause for hyperbilirubinemia
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Intrahepatic cholestasis
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Post-hepatic cause for hyperbilirubinemia
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Extrahepatic cholestasis
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What bilirubin form increases due to extrahepatic cholestasis?
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Conjugated
- Unconjugated can increase with severity of damage |
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What causes a marked elevation in TBIL in horses?
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Anorexia for more than 24 hours
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What is bile acid produced from?
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Cholesterol
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How long should dogs and cats be fasted for a bile acid test?
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Overnight
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What species does not require fasting for a bile acid test, and why?
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Horses
- Continually secrete bile |
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What disease process provides the highest increase in serum bile acids?
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Portosystemic shunts
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What disease process provides a moderate increase in bile acid levels? (2)
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- Acute hepatitis
- Hepatic neoplasia |
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Bile acid level trend in a suspected hepatic insufficiency
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Increased
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Albumin level trend in a suspected hepatic insufficiency
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Decreased
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BUN level trend in a suspected hepatic insufficiency
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Decreased
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Ammonia level trend in a suspected hepatic insufficiency
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Increased
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Glucose level trend in a suspected hepatic insufficiency
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Decreased
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What liver value is the most important to test for in hepatic insufficiency?
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Ammonia
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What enzyme is highly specific and sensitive for muscle damage?
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Creatinine kinase
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What should CK always be evaluated in conjunction with?
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AST
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Two types of CK isoenzymes found in skeletal and cardiac muscle
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CK-2
CK-3 |
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What does an increased ALT greater than AST increase with no CK increase indicate in dogs and cats?
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Liver injury
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What does an increased AST greater than ALT increase with CK increase indicate dogs and cats?
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Skeletal muscle injury
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What does an increased AST with no CK increase indicate in large animals?
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Liver injury
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What does an increased AST with CK increase indicate in large animals?
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Skeletal muscle injury
- or - Skeletal muscle injury with concurrent liver injury |