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Enz mes in dia nosis
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Most clinical enzyme measurements using serum
(plasma), occasionally other fluids, such as urine
and gut secretions, are investigated.
Blood lasma contains man enz mes which are
classified into:
1. Functional plasma enzymes
2. Non functional plasma enzyme
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Differences between functionaland non functional enzymes
Functional plasma
enzymes
Non functional
plasma enzymes
Concentration in
plasma
Present in plasma in higher
concentrations in comparison to
tissue
Normally, Present in plasma in
very low concentrations in
comparison to tissue
Functionave nown unct ons o nown unct ons
Substrate Their substrates are alwayspresent in plasma
Their substrates are absent from
plasma
Site of synthesisliver Different organs .g. liver heart,
skeletal muscles and brain
Effect of disease Decrease in liver disease Increase in
different organdiseases
Examples Clotting factors e.g. Prothrombin
Lipoprotein lipase,Pseudocholinesterase
ALT, AST, CK, LDH, alkaline
phosphatase, acid phosphataseand lipase
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Source of non functionalenzymes Cell damage with the release of
its content of enzymes
into blood e.g. Myocardial infarction and viral hepatitis
Obstruction of normal pathways e.g. Obstruction of
e uct ncreases a a ne p osp atase
Increase of the enzyme synthesis e.g. bilirubinincreases the
rate of synthesis of alkaline phosphatase
in obstructive liver disease
Increased permeability of cell membrane as in hypoxia
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Medical importance of non functionalenzymes
Measurement of non functional enzymes isimportant for:
. different organs cause elevation ofdifferent plasma
enzymes
2. Prognosis of the diseasewe canfollow up of the treatment by
measuringplasma enzymes before and after
treatment
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Diagnostically Important EnzymesName of the enzyme
Conditions in which level of activityin serum is elevated
Aspartate Amino transferase (AST)
Serum glutamate-oxaloacetate transaminase(SGOT)
Myocardial infarction, Liver disease especially with
liver cell damage
Alanine Amino transferase (ALT)
Serum glutamate-pyruvate transaminase
Liver disease especially with liver cell damage
Alkaline Phosphatase (ALP) Liver disease- biliary
obstruction
Osteoblastic bone disease-rickets
Acid Phosphatase (ACP) Prostatic carcinoma
glutamyl Transferase (GT) Liver disorder like liver
cirrhosis
Creatine kinase (CK) Myocardial infarction and skeletal
muscledisease(muscular dystrophy
Lactate Dehydrogenase (LDH) Myocardial infarction, other
diseases like liverdisease.some blood diseases
Amylase Acute pancreatitis
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Levels of enzymes in diseases involvingliver damageIn viral
hepatitis
Rapid rise intransaminases (AST &ALT) in serum occurseven
before bilirubin rise
is seen
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AST and CKrise in 6 hours
following acute myocardialinfarction
Levels of enzymes in myocardial
infarction
CK
CK-MB
AST
LDH
-
dehydrogenase) and LDHare elevated much later andremains high
for a longerperiod of days
