10. Enzymology - Clinical Enzymes & Cardiac Markers Flashcards

Terms Definitions
What is the difference between intra and extracellular enzymes?
Intracellular = inside organs/cells, have no function in plasma.Extracellular = function in plasma.
What is the diagnostic level of extracellular enzymes?
When plasma level is decreased; they should normally be measurable in the plasma.
What are the 2 types of intracellular enzymes?
1. Secreted2. Metabolic
What are the diagnostic levels of secreted enzymes?
Increased - when mode of secretion (excretion) is blockedOR Decreased - when tissue is damaged.
What are the diagnostic levels of metabolic enzymes?
Increase - shows that cell damage has occured.
Give 4 examples of Enzymes of secretion:
1. Amylase2. Lipase3. Acid phosphatase4. Alkaline phosphatase
Give 4 examples of Metabolic enzymes:
1. CK2. LD3. AST4. ALT
Where are EXTRACELLULAR enzymes made?
In the liver
What are examples of extracellular enzymes?
Blood coagulation enzymes
Give 2 examples of enzymes that are tumor markers:
PAP and CK
What would be the diagnostic level of enzymes as tumor markers?
Increased - from tumor growth.
What is the tissue source of LD1?
Heart and RBCs
What is the tissue source of LD2?
Renal
What is the tissue source of LD3?
Lung, spleen and pancreas
What is the tissue source of LD4 and LD5?
Liver and skeletal muscle
What are 5 analytical methods for measuring isoenzymes?
1. Ion exchange chromatography2. Immunoinhibition3. RIA4. Heat fractionation5. Electrophoresis
What type of enzyme is LD?
Oxidoreductase
What 2 preanalytic variables alter LD measurement?
-Gross hemolysis -Temp of storage - should be 25C or less.
How is LD activity measured?
By monitoring absorbance at 340 nm via oxidoreduction of NADH - but the ref ranges are different depending on direction of reaction.
In what 5 diseases are LD levels clinically significant? What isotypes in each disease?
Heart disease - LD1>LD2 (flip)Anemia: Increased LD1Pulmonary: Increased LD3Malignancy: Increased LD3Liver: increased LD4/LD5
What does a normal LD electrophoresis show for levels?
2>1>3>4>5
What effect does MI (heart dis) have on LD electrophoresis?
1>2>3>4>5 --- LD flip
What is a faster way to measure LD-1 than the time consuming electrophoresis?
Antibody against M-subunit precipitates all but LD1
What type of enzyme is CREATININE KINASE?
Transferase
What method is used for measuring CK on automated analyzers?
Reaction inhibition
What preanalytic variables must be controlled for CK samples?
1. Hemolysis2. Store in dark or CK levels will decrease
What are the 3 isotypes of CK?
1. CK-MM2. CK-MB3. CK-BB
What tissue is each CK isotype specific for?
CKMM = Mostly MuscleCKMB = Heart and MuscleCKBB = Brain, bladder, etc.
Which CK isotype is elevated in:-Myocardial infarct?-Brain damage/tumor?-Injections/exercise/injury?
Injections/injury = CK-MMMI = CK-MBBrain dmg = CK-BB
What are ALT/AST clinical markers of?
Liver disorders
Generally which is higher in hepatic damage, AST or ALT?
ALT is usually higher than AST.
What does AST >> ALT indicate?
Poor prognosis and massive cell necrosis.
What can alter ALT and AST measurements?
hemolysis
what type of enzymes are ALT and AST?
Transferases
What type of enzyme is ALP?
hydrolase
What are 3 preanalytic variables of ALP measurement?
-Needs pH of 10-12-Needs Mg2+-hemolysis greatly increases levels falsely
What is the clinical significance of ALP measurement?
Bone and Liver
What type of liver disease does increased ALP indicate?
Biliary tract obstruction
What is the clinical significance of 5' Nucleotidase?
Liver: Increased in hepatobiliary disorders
What is the clinical significance of GGT?
Liver - ALCOHOLISM
What 3 enzymes are clinically significant indicators of Pancreatic disease?
Amylase, Lipase, and Aldolase
What is the clinical significance of ACP?
(acid phosphatase)-Can be used to detect prostate cancer that is metastesized (but the PSA is better method now).
What is the clinical significance of Cholinesterase?
Used as an indicator of poisoning with anesthesia or organic pesticides.
What are important Cardiac markers? Which is elevated first after MI?
1. Myoglobin (first)2. Troponin (more sensitive)3. CK-MB
What enzyme will not be affected by hemolysis?
GGT - it is NOT in RBCs
Regarding ALP, where are each isoform found? (1, 2, 3)
ALP1 = liverALP2 = boneALP3 = intestine
How can ALP1 and 2 be seperated?
Liver lives, bone burns - susceptible to heat denaturation
How can 5-nucleotidase aid in ruling out liver disease?
If ALP is increased but 5-nucleotidase is normal, then you could suspect bone disease. To confirm, run an AST.
What type of liver disease would 5-nucleotidase be elevated in?
hepatobiliary disease
What type of enzyme is 5-nucleotidase?
hydrolase, like ALP
So what are all the hydrolases?(7)
-ALP/ACP-5'nucleotidase-Amylase/lipase-Cholinesterase-Aldolase
which enzyme will NOT be affected by hemolysis?
GGT
Which enzymes can aid in differentiating ALP bone from liver disease?
5-nucleotidaseGGT
GGT is more specific for ___ than for ___
Alcoholism than for cirrhosis
which enzymes are specific for pancreas?
Amylase, Lipase, Aldolase
Which enzyme is specific for prostate?
Acid phosphatase - ACP
Which pancreatic enzyme remains elevated longer?
Lipase longer than amylase
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