Enzymes (part two) Flashcards
What are the 5 major liver enzymes
- Aspartate aminotransferase
- Alanine aminotrasferase
- Alkaline phosphatase
- Gamma-glutamyl transerase
- Cholinesterase
Aspartate Amiontransferase (AST) - Three biological sources
- Heart
- Skeletal Muscle
- Liver
(4. Kidney)
Aspartate Amiontransferase (AST) - typical appearance, peak, and return to normal after myocardial infarction
Rises within 12 hours after onset of chest pain; peaks at 18-24 hours; normal within 4-5 days
Aspartate Amiontransferase (AST) -Two liver diseases that give rise to the greatest elevations
Liver (hepatocellular) Disease
- Viral Hepatitis
- Liver carcinoma
Aspartate Amiontransferase (AST) - One muscular disease in which AST is elevated
- Skelatal Muscle Disease (Muscular Dystrophy)
Aspartate Amiontransferase (AST) -If hemolyzed specimens are unacceptable
UNACCEPTABLE
-due to high intracellular concentration of AST
Principle biological source of ALT
Liver
alanine aminotransferase (ALT) -relative use in the diagnosis of liver disease, compared to AST
useful in the diagnosis of acute and chronic liver disease; parallels the rise in AST activity
alanine aminotransferase (ALT) -liver diseases in which it is elevated
ALT higher and persists longer than AST in hepatitis
alanine aminotransferase (ALT) -Hemolysis acceptibility?
NO HEMOLYSIS
Alkaline Phosphatase (ALP) - four principal biological sources of total ALP
liver, bone, intestine, placenta
Alkaline Phosphatase (ALP) - Hepatobiliary diseases in which ALP is increased
biliary obstruction, hepatitis, cirrhosis, infectious mono, and metastic carcinoma
Alkaline Phosphatase (ALP) - The hepatobiliary disease which gives rise to ALP's highest elevations
Biliary Obstruction
Alkaline Phosphatase (ALP) - Bone diseases in which ALP is increased
Bone tumors, Paget’s Disease, Rickets, osteomalacia, hyperparathyroidism, and healing fractures
Alkaline Phosphatase (ALP) - Two bone diseases which tie rise to ALP's highest elevations
Bone tumors and Paget’s Disease
Alkaline Phosphatase (ALP) - If hemolyzed specimens are unacceptable
Gross hemolysis NOT acceptable (slight ok but must be documented)
Alkaline Phosphatase (ALP) - Principle of the Bowers and McComb procedure using p-nitrophenylphosphate
reference method; kinetic method that uses pNPP as substrate and measures the rate of p-nitrophenoxide release in AMP buffer
Which specific isoenzymes may be distinguished using the heat stability, urea denaturation, amino acid inhibition, and electrophoretic techniques
Alkaline Phosphatase (ALP)
Alkaline Phosphatase (ALP) - Why the reference range is higher in children than in adults
due to rapid bone growth
gamma-glutamyltransferase (GGT)
-two principle biological sources
primarily liver, also kidney
gamma-glutamyltransferase (GGT)
-degree of elevation used in the differential diagnosis of hepatocellular VS biliary tract disease
Elevation up to 5X ULN in biliary tract disorders; lesser elevation (2-5X) in viral hepatitis or active cirrhosis
gamma-glutamyltransferase (GGT)
-clinical usefulness in the diagnosis and monitoring of chronic alcoholism
GGT is induced by alcohol and other drugs; used as a marker to check for abstinence from alcohol
cholinesterase (ChE) in vivo reaction it catalyzes
Both enzymes hydrolyze choline esters to form choline and the corresponding fatty acid at the neuromuscular junction
Three clinical applications of measuring ChE activity
1 assess exposure to organophospahtes found in insecticides and nerve gas
2 check how patient will react to general anesthesia
3 assess presence of cirrhosis, hepatitis, liver carcinoma (due to decreased production)
Sources of AChE (acetylcholinesterase)
Red blood cells and central nervous system
Sources of cholinesterase (ChE)
Liver, white matter of brain, serum