Plasma Enzymes And iso Enzymes In Diagnosis Flashcards
Clinical Enzymology is defined as the _______ in body fluids and the use of this information to _______ or to _________
assay of enzymes
make a diagnosis
monitor a clinical condition.
An isoenzyme refers to ___________ but from __________
multiple forms of an enzyme
the same genetic origin.
Isoenzymes have the same ________ but different ______ such as electrophoretic mobility, solubility or resistance to inactivation
catalytic function
physical properties
A macroenzyme is a _________ form of the native enzyme which is often ________
high molecular weight
complexed with immunoglobulins
Macroenzymes are more commonly seen in individuals with ________ and they often times present a source of ________
autoimmune disease
diagnostic confusion.
Causes of increased Plasma enzyme levels
Specific Causes
High plasma enzyme activities are seen in situations of
•Increased ________ eg in cancer
•Increase in _______ eg in viral hepatitis
•Increase in _______ (eg in microsomal enzyme induction)
•Decreased _______ eg amylase in renal impairment.
proliferation of cells
cell damage
enzyme synthesis
clearance from the plasma
Non specific causes of raised plasma enzyme activity
Mild increases in ______ are seen in many illnesses
Increase in ____ is seen in moderate exercise and IM injection
Increase in ____ seen in phenytoin use
Increase in ______ seen in renal impairment or macroamylsaemia
AST
CK
GGT
amylase
Physiological factors that affect plasma enzyme assays
Age eg ____
Sex –_____ and ____ activity are higher in men than women
ALP
GGT and CK
Physiological factors that affect plasma enzyme assays
Race and ethinicity - plasma ____ is higher in the negroid race than in caucasians
Physiological conditions – high _____ in pregnancy.
CK
ALP
Creatine Kinase
CK is an enzyme with a molecular weight of approximately 82,000 that is generally associated with _____ in the ______
ATP regeneration
muscle
Creatine Kinase
Tissue Source
CK is widely distributed in tissue, with highest activities found in _______,________, and ______.
skeletal muscle, heart muscle, and brain tissue
Creatine Kinase
Diagnostic Significance
Because of the high concentrations of CK in ____ tissue, CK levels are frequently elevated in disorders of _____ and ____ muscle.
The CK level is considered a sensitive indicator of ___________ and ________.
muscle
cardiac and skeletal
acute myocardial infarction (AMI) and muscular dystrophy
________________ (AMI)
acute myocardial infarction
Creatine Kinase
Because enzyme elevation is found in numerous disorders, the separation of total CK into its various isoenzyme fractions is considered a more specific indicator of various disorders than total levels.
T/F
T
Creatine kinase
CK occurs as a _____ consisting of two subunits that can be separated readily into three distinct molecular forms.
The three isoenzymes have been designated as _______,_________, and_________
dimer
CK-BB (brain type), CK-MB (hybrid type), and CK- MM
(muscle type).
Based on electrophoretic mobility, the iso enzymes of creatine kinase are also designated thus:
CK-1 (_____) – migrates fastest to the anode
CK-2 (_____)
CK-3 (______)
CKBB
CKMB
CKMM
Creatine Kinase
Reference Range
Total CK:
Male, ______ U/L (37°C)
Female,______ U/L (37°C)
CK-MB: __% total CK
15–160
15–130
6
Creatine kinase
The higher values in males are attributed to _________
increased muscle mass.
Aspartate aminotransferase
Aspartate aminotransferase (AST) is involved in the transfer of an ____ between ______ and _____
amino group
aspartate and -keto acids.
Aspartate aminotransferase
The older terminology, ____________________ may also be used.
________ functions as a coenzyme. The reaction proceeds thus:
serum glutamic- oxaloacetic transaminase (SGOT, or GOT),
Pyridoxal phosphate
Aspartate aminotransferase
Aspartate + α – ketoglutarate → ________ + _________
oxaloacetate + glutamate
Aspartate aminotransferase
The transamination reaction is important in intermediary metabolism because of its function in the synthesis and degradation of amino acids. The ketoacids formed by the reaction are ultimately ___ by the ______ cycle to provide a source of energy.
oxidized
tricarboxylic acid
Aspartate aminotransferase
Tissue Source
The highest concentrations are found in ______,________, and _______ , with smaller amounts found in the ____,____, and _____
cardiac tissue, liver, and skeletal muscle
kidney, pancreas, and erythrocytes.
AST is widely distributed in human tissue.
T/F
T
Aspartate aminotransferase
Diagnostic Significance
The clinical use of AST is limited mainly to the evaluation of ______ disorders and ___________ involvement.
hepatocellular
skeletal muscle
In AMI, AST levels begin to ___________, then it _______, and generally _______________
rise within 6 to 8 hours
peaks at 24 hours
return to normal within 5 days.
AST levels are useful in the diagnosis of AMI.
T/F
F
because of the wide tissue distribution,
AST levels are highest in ________ disorders.
acute hepatocellular
In viral hepatitis, AST levels may reach _____ times ULN. In cirrhosis, , levels may reach ___ times ULN
100
4
Aspartate aminotransferase
Source of Error
_______ should be avoided because it can dramatically increase serum AST concentration.
Reference Range
AST, 5 to 30 U/L (37°C)
Hemolysis
Alanine aminotransferase
Alanine + α ketoglutarate → _____ + ______
_________ is the co factor for the reaction
Pyruvate + Glutamate
Pyridoxal phosphate
