clinical enzymology 231 k
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ClinicalEnzymology
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Enzymes are the protein catalysts that increase the rate of specific
chemical reaction in the body.
Enzymes are found in small amounts mainly within cells ,clotting
factors and digestive enzymes function naturally after secretion:
- Plasma specificThrombin- Secreted- Lipase, Amylase
- Intracellular- transaminases, creatine kinase
Injury or death of tissues can cause the release of tissue-specific
enzymes into the bloodstream.
Elevated enzyme levels are often indicators of tissue problems, and
are used in the diagnosis of diseases.
Enzyme activities in the body fluids are altered by pathological
rocesses so its measurement is used for disease investi ation.
INTRODUCTION
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All known enzymes are proteins.
They are high molecular weight compounds made up principally
of chains of amino acids linked together by peptide bonds.
Enzymes can be denatured and precipitated with salts, solvents
and other reagents.
They have molecular weights ranging from 10,000 to 2,000,000.
Many enzymes require the presence of other compounds -
cofactors - before their catalytic activity can be exerted.
This entire active complex is referred to as the HOLOENZYME;
i.e., APOENZYME (protein portion) plus the COFACTOR
(coenzyme, prosthetic group or metal-ion-activator) .
Chemical Nature of Enzymes
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Apoenzyme + Cofactor = Holoenzyme
The Cofactor may be:
1 A coenzyme - a non-protein organic substance
which is dialyzable, thermostable and looselyattached to the protein part.
2 A prosthetic group - an organic substance which
is dialyzable and thermostable which is firmlyattached to the protein or apoenzyme portion.
3 A metal-ion-activator - these include K+, Fe++,
Fe+++, Cu++, Co++, Zn++, Mn++, Mg++, Ca++, and
Chemical Nature of Enzymes contd.
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Enzymes can be classified by the kind of chemical reaction
catalyzed.A. Addition or removal of water :
1. Hydrolases - these include esterases, carbohydrases, nucleases,
deaminases, amidases, and proteases
2. Hydrases such as fumarase, enolase, aconitase and carbonic
anhydrase
B. Transfer of electrons :
1. Oxidases
2. Dehydrogenases
Classification of Enzymes :
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Classification of Enzymes contd. C. Transfer of a radical:
1. Transglycosidases - of monosaccharides
2. Transphosphorylases and phosphomutases - of a phosphategroup
3. Transaminases - of amino group
4. Transmethylases - of a methyl group
5. Transacetylases - of an acetyl group
D. Splitting or forming a C-C bond:
1. Desmolases
2. Changing geometry or structure of a molecule
3. Isomerases
E. Joining two molecules through hydrolysis ofpyrophosphate bond in ATP or other tri-phosphate
1. Ligases
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One of the properties of enzymes that makes them so
important as diagnostic and research tools is the specificity
they exhibit relative to the reactions they catalyze.
Greater specificity is achieved in three ways:
1. Interpreting investigations in the light of clinical features
2. Test pattern recognition
3. Isoenzyme determination:
- ASTmay be due toMIorHepatitis so, itmakesconfusion in diagnosis to be confirmed by LDH levels.
- ALP inCholestasis & bone diseases :- Differentiated by bilirubin & transaminase levels inCholestasis .
- Confirmed by GGT in Cholestasis.
Specificity of Enzymes :
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Specificity of Enzymes contd.In general, there are four distinct types of specificity:
Absolute specificity - the enzyme will catalyze only onereaction.
Group specificity - the enzyme will act only on molecules
that have specific functional groups, such as amino,phosphate and methyl groups.
Linkage specificity - the enzyme will act on a particular type
of chemical bond regardless of the rest of the molecularstructure.
Stereochemical specificity - the enzyme will act on a
particular steric or optical isomer.
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Rate of entry into blood
Serum enzyme activity
Rate of removal
Inhibition
Rate of synthesisMass of enzymeProducing tissue
Tissue damage
ClearanceInactivation
Factors affecting serum enzyme activity
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I- Rate of entry of enzymes into blood is affected by:
aRate of synthesisof enzyme:- Biliary obstruction hepatobiliary tree enzymes- Drugs:Anticonvulsant drugs ( Phenobarbital & phenytoin) synthesis of enzymes by the hepatocytes
b- Mass of enzyme producing cells as in:
- alkaline phosphatase: ( in active growth , Pagets disease.and in 3rd trimester pregnancy).
- acid phosphatase ( in cancer prostate).c- Necrosis orCell damage as in:
- Hepatitis transaminases- Myocardial infarction CK- Stored blood LDH
Factors affecting Serum enzyme activities-1
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II-Enzyme inhibitors:- Little effect on enzyme values determined in the lab.
- Organophosphorus poisoning irreversible inhibition ofcholinesterase.
III- Clearance of enzymes:
- Breakdown by Proteases and removal by the reticuloendothelial
system.
- Renal excretion of small molecular enzymes e.g.Amylase
Factors affecting Serum enzyme activities-2
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Schematic diagram showing the effect of temperature on rate
of nonenzyme-catalyzed and enzyme catalyzed reactions.
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Enzymes have anactive site- a cleft into
which substrate molecules fit
The active sitecontains amino acids that:
- Attract the substrate
-
Assist in the chemical reactions that convertssubstrate to product
How does an enzyme work?
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1) E + S ES. Enzyme and Substrate collide.
Substrate binds to active site of enzyme.
A transition state forms where the structure of the substrate is
altered.
2) ES EP. Enzyme catalyses the conversion of substrate to Product.
Both substrate and product remain in active site.
3) EPE + P. Product is released from active site.
Sequence of events in enzyme catalyzed reaction
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ISOENZYMES
Catalyze the same reaction
Two or more polypeptide chains
Different polypeptide chains are products ofdifferent genes
Differ in AA sequence and physical properties
May be separable on the basis of charge Are tissue specific
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Aminotransferases:
ALT
AST
GGT
ALT and AST :
1. Pyridoxal dependent2. Indicates Hepatitis, Myocardial infarction:
- Elevations take > 4 hours to develop, last 4 days
- ALT elevation lasts longer than AST
- AST elevations are higher than ALT
- Elevations occur in most definite infarctions
3. Skeletal muscle damage
4. Hemolysis
5. Pancreatitis
Isoenzymes and multiple forms
i f
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GGT
Hepatobiliary enzyme - highly inducible in 75% of the
population
Highest increases in intra or posthepatic biliary
obstruction
Higher and more persistent increases than AlP (Alkaline
Phosphatase)
Isoenzymes and multiple forms
Di ill i h i i f I
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Diagram illustrating the origin of Isoenzymes
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Transaminase activities in human tissues,
relative to serum as unity
AST ALT
Heart 7800 450
Liver 7100 2850
Skeletal Muscle 5000 300
Kidney 4500 1200
Pancreas 1400 130
Spleen 700 80Lung 500 45
Erythrocytes 15 7
Serum 1 1
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Diagnostic Enzyme Analysis
Cellular/Plasma specific activities of various enzymes:
Tissue AST ALT LDH CK
(GOT) (GPT)
Heart 8000 400 1000 10000
Liver 7000 3000 1500
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LDH-Lactate Dehydrogenase in MI
LDH is a tetramer of two non-identical subunits (LDH5(M4),LDH4(M3H), LDH3(M2H2), LDH2(MH3), LDH1(H4)
ENZYMES OF CLINICAL INTEREST
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Acid phosphatase (ACP)
Amylase (AMS) Alanine aminotransferase (ALT)
Alkaline phosphatase (ALP)
Aspartate aminotransferase (AST)
Creatine kinase (CK)
Gamma-glutamyltransferase (GGT)
Glucose 6-phosphate dehydrogenase (G6PD)
Lactate dehydrogenase (LDH or LD)
Lipase (LPS)
Plasma cholinesterase
ENZYMES OF CLINICAL INTEREST
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Diagnostically Important Enzymes 1/3
Principle Clinical
Applications
Principal SourcesEnzyme
Carcinoma of prostateProstate, erythrocytesAcid
Phosphatase (ACP)
Hepatic parenchymal
disease
Liver, Skeletal muscle,
Heart
Alanine
aminotransferase(ALT)
Muscle diseaseSkeletal muscle, heartAldolase
Bone diseases,
hepatobiliary diseases
Liver, bone, intestinal
mucosa, placenta,kidney
Alkaline
Phosphatase (ALP)
Pancreatic diseasesSalivary glands,
pancreas, ovariesAmylase(AMS)
Myocardial infarction,
hepatic parenchymal
Liver, skeletal muscle,
heart, kidney,Aspartate
aminotransferase(AST)
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Diagnostically Important Enzymes 2/3
Principle Clinical
Applications
Principal SourcesEnzyme
Organophosphorus
insecticide poisoning,
suxamethonium
sensitivity, hepaticparenchymal diseases
LiverCholinesterase
Myocardial
infarction, muscle
diseases
Skeletal muscle,
brain, heart, smooth
muscle
Creatine kinase(CK)
Hepatic parenchymal
disease
LiverGlutamate
dehydrogenase
Hepatobiliary
disease, alcoholism
Liver, kidneygamma-GT(GGT)
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Diagnostically Important Enzymes 3/3
Principle Clinical
Applications
Principal SourcesEnzyme
Myocardial
infarction, hemolysis,
hepatic parenchymal
disease
Heart, liver, skeletal
muscle, erythrocytes,
platelets, lymph
nodes
Lactate
dehydrogenase(LDH)
Hepatobiliary diseaseHepatobiliary tract5 Nucleosidase
Parenchymal hepaticdisease
LiverSorbitoldehydrogenase
Pancreatic diseasesPancreasTrypsin(ogen)
A id h h t (ACP)
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Found in prostate, bone, liver, spleen, kidney, RBCs
and platelets
Primarily used to diagnose prostate cancer . In other prostatic conditions e.g. prostatitis, benignprostatic hypertrophy.
In other non prostatic conditions e.g. hemolysis, Pagets
disease, metastatic carcinoma of the breast & Gauchers
disease.
Prostate- Specific Antigen(PSA):an enzyme occurs in prostatic
tissue andin cases of metastatic carcinomaTartarate inhibits the prostatic ACP enzyme while
Acid phosphatase (ACP)
Al i i t f (ALT)
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Alanine aminotransferase (ALT)
Widely distributed, although the largest amountsfound in the liver.
Smaller amounts occur in the heart but usually
remains normal after MI .
Congestive cardiac failure release from the liverMore specific for liver disease than AST.
Alk li h h t (ALP)
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Widely distributed, high concentrations in intestines,
liver, bone, spleen, placenta and kidney.
The main sources of serum ALP are the hepatobiliary
tree and bone disorders.
Elevated levels during healing of fractures , activegrowth and during the 3rd trimester of pregnancy.
serum ALP activity in liver disease is mainly due toCholestasis.
Decreased levels are found in the inherited condition
Hypophosphatasia which is caused by defective bone
calcification
Alkaline phosphatase (ALP)
Alk li h h t (ALP)
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Alkaline phosphatase (ALP)Causes of increased serum alkaline phosphatase enzyme activity:
Physiological :
Bone disease:
Hepatobiliary disease:
Others:
- Infancy- Puberty
- Pregnancy
- Intestinal isoenzymes
- Hyperparathyroidism- Osteomalacia, rickets
- Pagets disease of bone
- Osteomyelitis
- Hepatitis
- Cholestasis
- Cirrhosis
Carcinoma of the bronchus
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Alkaline Phosphatase
Bone Alkaline Phosphatase
Males
Females
4 8 12 16 20 (Years)
Alk.Phos.units
A l (AMS)
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Hydrolases that split complex Polysaccharides.
- alpha-amylases (1-4 alpha links attacked at random)
- MW 40,000 - filtered by kidney
- Ca+2 requiring metalloenzyme
Sources :
1. Pancreas (p-type)
2. Salivary glands (s-type)
3. Intestinal malignancy
Amylase (AMS)
A l (AMS)
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Clinical Significance : Diagnosis and monitoring of
pancreatitis1. Acute: - transient increase in activity within 2 - 12 hours
- returns to normal in 3 - 4 days
2.Extent of increase (typically 4 - 6 fold) related to probability ofacute pancreatitis.
3. Serum amylase activitymay be falsely normalin presence ofsevere dyslipidaemia - check urinary amylase.
4. Serum amylasemay be raised in biliary duct obstruction.
5. Serum amylase activitymay be normal in chronic pancreatitis.
6. Amylasemay be raised in pleural effusions and pseudocysticfluids secondary to pancreatitis.
7. Salivary gland diseases or traumamay raise serum amylaseactivity.
Amylase (AMS)
S li E i N l F ti d
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Salivary Enzymes in Normal Function and
Abnormal Pathology
-Amylasenormally present in salivaimportant in digestion
______________________________________________
Lysozyme Hyaluronidase
Chondrosulfatase
Aryl Sulfatase
Neutral Protease
Collagenases
Specific activities are increased in
gingivitis and periodontal disease
Causes of Hyperamylasemia and Hyperamylasuria
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1. Pancreatic disease (P-type):
Pancreatitis:
- Acute
- Chronic
- Complications: Pseudocyst
Ascites and pleural effusion
Abcess Pancreatic Trauma, including investigative maneuvers
Pancreatic carcinoma
Causes of Hyperamylasemia and Hyperamylasuria
Causes of Hyperamylasemia and Hyperamylasuria
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2. Disorders of non-pancreatic origin
(mechanism unknown) :a-Renal insufficiency (mixed)
b-Neoplastic hyperamylasemia - usually bronchogenic
or ovarian (usually S-type)
c-Salivary gland lesions, e.g. mumps, calculus disease
(S-type)d-Macroamylasemia (predominantly S-type)
Causes of Hyperamylasemia and Hyperamylasuria
Causes of Hyperamylasemia and Hyperamylasuria
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3. Disorders of complex origin (mechanism unknown or uncertain)
o Biliary tract disease
o Intra-abdominal disease (other than pancreatic diseases):
o Perforated peptic ulcer (P-type)
o Intestinal obstruction (P-type)
o Mesenteric infarction (P-type)
o Peritonitis (mixed; depends on cause)
o Acute appendicitiso Ruptured ectopic pregnancy (S-type)
o Aortic aneurysm with dissection
o Cerebral trauma (type depends on other organ damage)
o Burns and traumatic shock
o Postoperative hyperamylasemia (usually S-type)
o Diabetic ketoacidosis (mixed)
o Renal transplantation (S-type)
o Acute alcoholism (mixed)
o Drugs: - Medicinal opiates (P-type) - Heroin addiction (S-type)
Causes of Hyperamylasemia and Hyperamylasuria
A t t i t f (AST)
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This enzyme is widely distributed in the body.
Main sources: Heart, liver, skeletal muscle, and kidney.
Useful in the diagnosis of MI, liver disorders and muscle damage.
Causes ofserum AST levels:Physiological : Neonates.
Liver diseases: Hepatitis, hepatic necrosis , cholestasis
Cardiac disease:Myocardial Infarction.
Diseases of skeletal muscle:Crush injury,trauma,myopathy
From Erythrocytes:Hemolysis
Aspartate aminotransferase (AST)
C ti ki s (CK)
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Creatine kinase is associated with ATP regeneration in
muscle and nervous tissue. Elevated blood levels of CK are used as indicators of MI,
muscular dystrophy, and stroke.
CK occurs as a dimer of 2 different subunits, M and B.
- CK-BB: Brain type.
- CK-MB: Hybrid type.
- CK-MM: Muscle type.
These can be separated by electrophoresis.
CK-MB is released from cardiac muscle cells after MI.
Creatine kinase (CK)
Creatine kinase (CK)
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BB %MB %MM %
< 1 80
MM - skeletal
muscle
< 1> 40> 60MB - cardiac
muscle
> 95< 30BB - brain
Creatine kinase (CK)
A dimer - M and B protein strands which are the products of
different genes - true isoenzymes.
5% cutoff by general agreement
2 of 3 - history, ECG, enzymes
Gamma glutamyltransferase (GGT)
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A microsomal enzyme its synthesis induced by ethanol
and anticonvulsant drugs .
Found mainly in the kidney and significant amounts in
liver, brain, prostate, and pancreas .
Used primarily for diagnosis of hepatobiliary problems . ALT, AST and GGT are the main liver function tests .
Marked elevation of serum GGT level is seen in
alcoholic liver disease.
serum GGTactivity sometimes following MI orcongestive cardiac failure.
Gamma-glutamyltransferase (GGT)
Gl cose 6 phosphate deh drogenase (G6PD)
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First (and control) enzyme for pentose phosphate
pathway (P.P.P.). Important in production of NADPH + H+, especially in
RBC.
NADPH + H+ keeps glutathione reduced.
Antimalarial drugs are oxidants, and adversely affect
this system in RBCs.
Some populations, especially African-Americans, have ahigh frequency of G6PD deficiency.
If given antimalarial drugs, or fava beans, they develop
hemolytic anemia.
Glucose 6-phosphate dehydrogenase (G6PD)
Lactate dehydrogenase (LDH or LD)
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Converts pyruvate to lactate (and vice versa) during and
after anaerobic metabolism.
LDH occurs as a tetramer of 2 different subunits:
LD-1 (HHHH) from the heart:
Elevated after MI.
LD-2 (HHHM) from the kidney:
Elevated after renal infarction.
LD-3 (HHMM) from the lung, spleen and pancreas:Elevated in pulmonary embolism.
LD-4 (HMMM) and LD-5 (MMMM), both from the liverand skeletal muscle:
Elevated in injury to liver or skeletal muscle.
Lactate dehydrogenase (LDH or LD)
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Lipase (LPS)
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Breaks down fat into monoacylglycerol and free fatty acids.
Primarily from the pancreas.
Used to diagnose acute pancreatitis.
Pancreatic lipases :
- A group of enzymes that hydrolyze glycerol esters of long
chain fatty acids.- Some substrate specificity e.g. LPL (Lipoprotein Lipase).
- Bile salts are necessary for activity.
-Almost exclusively used clinically in the investigation of
pancreatitis.- Increase within 2 - 12 hours of acute attack.
- May remain elevated for many days .
- More specific to acute pancreatitis than amylase.
- Less sensitive to acute exacerbations in chronic pancreatitis.
Lipase (LPS)
Plasma cholinesterase
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Similar to cholinesterase in nervous system, degrades
acetylcholine (neurotransmitter and hormone).
Elevated in hepatitis and cirrhosis.
Also elevated in organophosphate (pesticide) poisoning.
Degrades succinylcholine, a muscle relaxant given
during general anesthesia in surgery.
Some people are deficient in plasma cholinesterase, so
the normal dose of succinylcholine would kill them
Therefore, a determination of plasma cholinesterase is
made prior to major surgery.
Plasma cholinesterase
Low Plasma Cholinesterase
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Low Plasma Cholinesterase
ExamplesCategory of cause
Infancy, 3rd Trimester of
pregnancyPhysiological reasons
Scoline sensitivity
(ChE variants)Inherited abnormality
Acquired abnormality:
Impaired protein synthesisA) Liver disease
Organophosphorusinsecticides
B) Industrial poisoning
Oral contraceptives, MAO
inhibitors, Cytotoxic drugsC) Drug effects
Pancreatic Trypsin
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A Serine Protease (hydrolyses peptide bondsformed by the carboxyl groups of
lysine/arginine).
Inactive Zymogens secreted (Type 1 and 2)
under the influence of vagus nerve . alpha1-antitrypsin and alpha2-macroglobulin
protect serum proteins (consider alpha-1 AT
deficiency).
Little clinical application in modern practice.
Pancreatic Trypsin
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Serum Enzymesin Disease
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Myocardial Infarction
Myocardial Infarction ( MI )
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Myocardial Infarction ( MI ) Necrosis of the myocardium, but not angina pectoris release of
CK, AST and LDH (HBD) into the circulation.
CK is the first to rise (activity within 6 h of MI ). Total CK reaches a peak at 24-36 h.
In uncomplicated cases, CK returns to normal within 3 days.
Serum AST more slowly ( maximum activity within 48 h) andreturns to normal in 4-5 days.
No significant elevation in HBD seen for the 1st 24 h (reaches
maximum at about 3 days & remain for up to 8 days). It is important to consider the timing of sample when interpreting
test results.
CK & HBD are useful as early and late indicators of MI, and more
specific than AST.
Myocardial Infarction ( MI )
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Myocardial Infarction ( MI ) CK from skeletal muscle may be following intramuscular
injection, chest compression for resuscitation or electrical
defibrillator.
CK specificity is by measuring CK-MB. HBD activity may bedue to non cardiac factors (hemolysis). Cardiac enzyme measurements are very sensitive indicators of
MI because it is in over 95% of cases. They are of particular value in the following conditions:
1. Atypical clinical presentation (absence of chest pain)
2. If the patient presents some time after a suspected event.
3. Difficulty in interpreting ECG (Arrhythmia or previous MI).
4. If further MI is suspected few days of a previous one.
CK-2 & CK-3 in normal subject and in patient
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CK 2 & CK 3 in normal subject and in patient
24 hrs after Myocardial Infarction
Creatine Kinase isoenzymes in blood
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Plasma levels following myocardial infarction
CPK---Creatine Kinase
LDH---Lactate Dehydrogenase
HBDH-Hydroxybutyrate
dehydrogenase
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Myocardial Infarction :
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Myocardial Infarction :
Plasma Enzymes Changes
Duration ofabnormality
(days)
Peak value of
abnormality(h)
Abnormalactivity
detectable(h)
Enzyme
1.5 - 312 - 243 - 10CK-MB isoenzyme
2 - 518 - 305 - 12Total CK
2 - 620 - 306 - 12AST
5 - 1430 - 488 - 16Heart-specific LD
Myocardial Infarction : Plasma enzymes
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Myocardial Infarction : Plasma enzymes
vs ECG
Specificity %Sensitivity %
10070ECG
9095PlasmaEnzymes
Troponin
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Troponin
Troponins are a complex ofI, T and C subunits
uniquely present in striated muscle and regulate thecalcium mediated interaction of actin and myosin.
Troponin-I has three isoforms:
sTnI (for fast twitch muscle);
TnI (for slow twitch muscle) and
cTnI (for cardiac muscle).
cTnI levels are elevated in plasma within 4 hr afterinfarction.
Better test than LDH and CKMB.
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Muscle DiseasesMuscular Dystrophy
Toxic Myopathy
Malignant Hyperpyrexia
Traumatic Myopathy
Muscular Dystrophy
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y p y
Genetically determined degenerative disorders.
Duchenne muscular dystrophy is an X-linked recessivedisorder caused by an abnormal dystrophin gene
(progressive weakness of muscles).
CK activitiesbefore the onset of clinical symptoms(values >10 times the normal upper level). Serum CK is in 75 % of female carriers.
Beckers muscular dystrophy is a benign form ofDuchenne MD.
CK elevated pattern similar to that of Duchenne MD.
Toxic Myopathy
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y p y
Causes:
- Drugs & chemicals (Alcohol, D-penicillamine, ..etc) generalized myopathy
- IM injections ( Trauma & Chemical irritation)
CK activity by narcotic analgesics given in MI. Rapid in body temp, shock& convulsions.(in general Anesthesia Serum CK activity during attacks . Pre-operative CK should be measured in patients with a
family history of malignant hyperpyrexia.
Malignant Hyperpyrexia
Traumatic Myopathies
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y p
Muscle trauma (surgery, I.M. injection, etc..) release of enzymes
High serum CK values occurspost-operatively .
If MI suspected, CK-MB should be measured.
Serum CK usuallyreturn to normal within 48 h of
a single intramuscular injection.
Vigorous exercise of short duration and prolonged
moderate exercise serum CK
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Liver DiseasesHepatic Necrosis
Hepatitis
CholestasisJaundice
Hepatocellular Damage
Liver Enzymes ( ALT, AST, GGT, ALP, LDH)
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Measurement of serum enzyme activities for :
a - Differential Diagnosis of Jaundice.
b - Monitoring of drug toxicity.
ALT is more specific than AST.
Hepatocellular disease has only modest effect on ALP &
GGT (up to 3 times the upper limit of normal)
In Cholestasis, Higher values of ALP & GGT due tosynthesis ( the values are 5-10 times the upper normal
level) .
y ( , , , , )
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Bone Diseases- Osteoporosis
- Osteomalacia
- Tumors
- Pagets Disease
Bone Enzymes - ( Alkaline Phosphatase) ALP
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ALP enzyme is usually normal in Osteoporosis as
osteoblastic activity is not increased
Modest of ALP in Osteomalacia and Rickets Healing fractures Transient of ALP 1ry & 2ry Hyperparathyroidism of ALP
In Pagets disease of bone of ALP (10 times) 1ry & 2ry bone tumors of ALP (5 times normal)
y ( p )
Enzymes in Urine
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Enzymes in UrineEnzymes appear in Urine from 2 sources:
- Filtration of plasma
- Leaking from cells lining the urinary tract
Amylase is normally detected in urine (small size).
Indicators of tubular damage:
- Alkaline phosphatase
- N-acetyl--glucosaminindase (NAG)
Enzymes in Hematological
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Enzymes in Hematological
Disorders
Inherited or acquired diseases - Hemolytic diseases
- Spherocytosis
- Methemoglobinemia
G-6-PD deficiency Hemolysison exposure tooxidant drugs as antimalarial drugs (Primaquine) oringestion of fava beans
Pyruvate kinase , Glutathione synthetase,Hexokinase Defects Hemolysis
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Thankyou
Enzymes
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Enzymes
Proteins.
Increase reaction rates by lowering activation
energy.
Increase rates by 10
6
-10
12
. Allow reactions to occur under much milder
conditions (low temperature, atmospheric
pressure, around neutral pH).
Enzymes do not affect the thermodynamic
properties of a reaction- they do not alter G.
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Some other Enzymes of Diagnostic Value
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y g
Plasma AST in:
Liver Disease Acute Renal Disease
Acute Pancreatitis
Alkaline Phosphatase Liver isoenzyme in:
Liver cancer and fatty liver
Bone isoenzyme in: Osteoblastic bone tumors
Maternal plasma AP up in the third trimester of
pregnancy
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Factors affecting serum enzyme concentrations
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1. Rate of entry
- tissue damage enzyme synthesis- extent of tissue damage
- concentration gradient
- rate of production
2. Rate of clearance
- breakdown by proteases
- removalby reticuloendothelial system
- renal excretion only foramylase(small molecular weight)
3. Induction
4. Proliferation
Functions of Released Enzymes
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Functions of Released Enzymes
Components of boneCollagen, Hyaluronic acid,
Sulfated glycoproteins, Hydroxyapatite
Hyaluronic Acid NAG + Glucuronic Acid
HU
Sulfated Glycoproteins NAG sulfate + GlucuronicAS, CS Acid
Acids produced breakdown the hydroxyapatite crystallattice
Bone Resorption
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p
Bone
Collagen type I Abnormal Hydroxyapatite Crystal
lattice
Collagenase type I
and Chains
Neutral Proteinase
Amino acids and peptides
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