2. Clinical Enzymology

3. INTRODUCTION
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 specific – Thrombin 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 processes so, its measurement is used for disease investigation.

4. Chemical Nature of Enzymes
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) .

5. Apoenzyme + Cofactor = Holoenzyme
Chemical Nature of Enzymes ……contd.
Apoenzyme + Cofactor = Holoenzyme
The Cofactor may be:
1 • A coenzyme - a non-protein organic substance which is dialyzable, thermostable and loosely attached to the protein part.
2 • A prosthetic group - an organic substance which is dialyzable and thermostable which is firmly attached to the protein or apoenzyme portion.
3 • A metal-ion-activator - these include K+, Fe++, Fe+++, Cu++, Co++, Zn++, Mn++, Mg++, Ca++, and Mo+++.

7. Classification of Enzymes :
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

8. Classification of Enzymes …… contd.
C.    Transfer of a radical:
    Transglycosidases - of monosaccharides
    Transphosphorylases and phosphomutases - of a phosphate group
    Transaminases - of amino group
    Transmethylases - of a methyl group
    Transacetylases - of an acetyl group
 D.   Splitting or forming a C-C bond:
   Desmolases
    Changing geometry or structure of a molecule
    3. Isomerases
   E. Joining two molecules through hydrolysis of pyrophosphate bond in ATP or other tri-phosphate
    1. Ligases

9. Specificity of Enzymes :
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:
Interpreting investigations in the light of clinical features
Test pattern recognition
Isoenzyme determination:
 AST may be due to MI or Hepatitis so, it makes
confusion in diagnosis to be confirmed by LDH levels.
-  ALP in Cholestasis & bone diseases :
- Differentiated by  bilirubin & transaminase levels in
Cholestasis .
- Confirmed by  GGT in Cholestasis.

10. Specificity of Enzymes ………contd.
In general, there are four distinct types of specificity:
Absolute specificity - the enzyme will catalyze only one reaction.
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 molecular structure.
Stereochemical specificity - the enzyme will act on a particular steric or optical isomer.

11. Factors affecting serum enzyme activity
Rate of synthesis
Tissue damage
Mass of enzyme
Producing tissue
Rate of entry into blood
Inhibition
Serum enzyme activity
Rate of removal
Inactivation
Clearance

12. Factors affecting Serum enzyme activities-1
I- Rate of entry of enzymes into blood is affected by:
a – Rate of synthesis of 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 , Paget’s disease.
        and in 3rd trimester pregnancy).
        -  acid phosphatase ( in cancer prostate).
c- Necrosis or Cell damage as in:
         - Hepatitis   transaminases
         - Myocardial infarction   CK
         - Stored blood   LDH

13. Factors affecting Serum enzyme activities-2
II- Enzyme inhibitors:
- Little effect on enzyme values determined in the lab.
- Organophosphorus poisoning  irreversible inhibition of
cholinesterase.
III- Clearance of enzymes:
- Breakdown by Proteases and removal by the reticuloendothelial
system.
- Renal excretion of small molecular enzymes e.g. Amylase

15. Schematic diagram showing the effect of temperature on rate of nonenzyme-catalyzed and enzyme catalyzed reactions.

16. How does an enzyme work? Enzymes have an active site- a cleft into
which substrate molecules fit
The active site contains amino acids that:
- Attract the substrate
- Assist in the chemical reactions that converts
substrate to product

19. Sequence of events in enzyme catalyzed reaction
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) EP ® E + P.
Product is released from active site.

21. ISOENZYMES Catalyze the same reaction Two or more polypeptide chains
Different polypeptide chains are products of different genes
Differ in AA sequence and physical properties
May be separable on the basis of charge
Are tissue specific

22. Isoenzymes and multiple forms
Aminotransferases:
ALT
AST
GGT
ALT and AST :
1.    Pyridoxal dependent
2.    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

23. Isoenzymes and multiple forms
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)

24. Diagram illustrating the origin of Isoenzymes

25. 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 80
Lung
500 45
Erythrocytes 15 7
Serum 1

26. Diagnostic Enzyme Analysis
Cellular/Plasma specific activities of various enzymes:
Tissue AST ALT LDH CK
(GOT) (GPT)
Heart
Liver <10
Skeletal
Muscle
RBC <1

28. LDH-Lactate Dehydrogenase in MI
LDH is a tetramer of two non-identical subunits (LDH5(M4), LDH4(M3H), LDH3(M2H2), LDH2(MH3), LDH1(H4)

29. ENZYMES OF CLINICAL INTEREST
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

30. Diagnostically Important Enzymes 1/3
Principle Clinical Applications
Principal Sources
Enzyme
Carcinoma of prostate
Prostate, erythrocytes
Acid
Phosphatase (ACP)
Hepatic parenchymal disease
Liver, Skeletal muscle, Heart
Alanine aminotransferase(ALT)
Muscle disease
Skeletal muscle, heart
Aldolase
Bone diseases, hepatobiliary diseases
Liver, bone, intestinal mucosa, placenta, kidney
Alkaline
Phosphatase (ALP)
Pancreatic diseases
Salivary glands, pancreas, ovaries
Amylase (AMS)
Myocardial infarction, hepatic parenchymal disease, muscle disease
Liver, skeletal muscle, heart, kidney, erythrocytes
Aspartate aminotransferase(AST)

31. Diagnostically Important Enzymes 2/3
Principle Clinical Applications
Principal Sources
Enzyme
Organophosphorus insecticide poisoning, suxamethonium sensitivity, hepatic parenchymal diseases
Liver
Cholinesterase
Myocardial infarction, muscle diseases
Skeletal muscle, brain, heart, smooth muscle
Creatine kinase (CK)
Hepatic parenchymal disease
Glutamate dehydrogenase
Hepatobiliary disease, alcoholism
Liver, kidney
gamma-GT (GGT)

32. Diagnostically Important Enzymes 3/3
Principle Clinical Applications
Principal Sources
Enzyme
Myocardial infarction, hemolysis, hepatic parenchymal disease
Heart, liver, skeletal muscle, erythrocytes, platelets, lymph nodes
Lactate dehydrogenase(LDH)
Hepatobiliary disease
Hepatobiliary tract
5’ Nucleosidase
Parenchymal hepatic disease
Liver
Sorbitol dehydrogenase
Pancreatic diseases
Pancreas
Trypsin(ogen)

33. Acid phosphatase (ACP)
Found in prostate, bone, liver, spleen, kidney, RBCs and platelets
Primarily used to diagnose prostate cancer .
 In other prostatic conditions e.g. prostatitis, benign prostatic hypertrophy.
In other non prostatic conditions e.g. hemolysis, Paget’s disease, metastatic carcinoma of the breast & Gaucher’s disease.
Prostate- Specific Antigen(PSA): an enzyme occurs in prostatic tissue and  in cases of metastatic carcinoma
Tartarate inhibits the prostatic ACP enzyme while Formaldehyde inhibits ACP from other sources

34. Alanine aminotransferase (ALT)
Widely distributed, although the largest amounts found in the liver.
Smaller amounts occur in the heart but usually remains normal after MI .
Congestive cardiac failure release from the liver
More specific for liver disease than AST.

35. Alkaline phosphatase (ALP)
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 , active growth and during the 3rd trimester of pregnancy.
 serum ALP activity in liver disease is mainly due to Cholestasis.
Decreased levels are found in the inherited condition “ Hypophosphatasia” which is caused by defective bone calcification

36. 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
- Paget’s disease of bone
- Osteomyelitis
- Hepatitis
- Cholestasis
- Cirrhosis
Carcinoma of the bronchus

37. Alkaline Phosphatase Bone Alkaline Phosphatase 4 8 12 16 20 (Years)
Males
Females
Alk. Phos.units
(Years)

38. Amylase (AMS) 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   

39. Amylase (AMS)
Clinical Significance : Diagnosis and monitoring of pancreatitis
1. Acute: - transient increase in activity within hours
- returns to normal in days
2. Extent of increase (typically fold) related to probability of acute pancreatitis.
3. Serum amylase activity may be falsely normal in presence of severe dyslipidaemia - check urinary amylase.
4. Serum amylase may be raised in biliary duct obstruction.
5. Serum amylase activity may be normal in chronic pancreatitis.
6. Amylase may be raised in pleural effusions and pseudocystic fluids secondary to pancreatitis.
7. Salivary gland diseases or trauma may raise serum amylase activity.

40. Salivary Enzymes in Normal Function and Abnormal Pathology
α-Amylase—normally present in saliva—important in digestion
______________________________________________
Lysozyme
Hyaluronidase
Chondrosulfatase
Aryl Sulfatase
Neutral Protease
Collagenases
Specific activities are increased in gingivitis and periodontal disease

41. Causes of Hyperamylasemia and Hyperamylasuria
1.   Pancreatic disease (P-type):
Pancreatitis:
- Acute
- Chronic
- Complications:
Pseudocyst
Ascites and pleural effusion
Abcess
Pancreatic Trauma, including investigative maneuvers
Pancreatic carcinoma

42. Causes of Hyperamylasemia and Hyperamylasuria
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)

43. Causes of Hyperamylasemia and Hyperamylasuria
 3. Disorders of complex origin (mechanism unknown or uncertain)
Biliary tract disease
Intra-abdominal disease (other than pancreatic diseases):
Perforated peptic ulcer (P-type)
Intestinal obstruction (P-type)
Mesenteric infarction (P-type)
Peritonitis (mixed; depends on cause)
Acute appendicitis
Ruptured ectopic pregnancy (S-type)
Aortic aneurysm with dissection
Cerebral trauma (type depends on other organ damage)
Burns and traumatic shock
Postoperative hyperamylasemia (usually S-type)
Diabetic ketoacidosis (mixed)
Renal transplantation (S-type)
Acute alcoholism (mixed)
Drugs: - Medicinal opiates (P-type) - Heroin addiction (S-type)

44. Aspartate aminotransferase (AST)
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 of serum 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

45. Creatine kinase (CK)
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.

46. Creatine kinase (CK) BB % MB % MM %
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
BB %
MB %
MM %
< 1
<20
> 80
MM - skeletal muscle
> 40
> 60
MB - cardiac muscle
> 95
< 3
BB - brain

47. Gamma-glutamyltransferase (GGT)
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 GGT activity sometimes following MI or congestive cardiac failure.

48. Glucose 6-phosphate dehydrogenase (G6PD)
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 a high frequency of G6PD deficiency.
If given antimalarial drugs, or fava beans, they develop hemolytic anemia.

49. Lactate dehydrogenase (LDH or LD)
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 liver and skeletal muscle:
Elevated in injury to liver or skeletal muscle.

50. Control
LDH Isoenzymes

51. Lipase (LPS) Pancreatic lipases :
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 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.

52. Plasma cholinesterase
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.

53. Low Plasma Cholinesterase
Examples
Category of cause
Infancy, 3rd Trimester of pregnancy
Physiological reasons
Scoline sensitivity
(ChE variants)
Inherited abnormality
Acquired abnormality:
Impaired protein synthesis
A) Liver disease
Organophosphorus insecticides
B) Industrial poisoning
Oral contraceptives, MAO inhibitors, Cytotoxic drugs
C) Drug effects

54. Pancreatic Trypsin
 A Serine Protease (hydrolyses peptide bonds formed 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.

55. Serum Enzymes
in Disease

56. Myocardial Infarction

57. 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 h.
In uncomplicated cases, CK returns to normal within 3 days.
Serum AST  more slowly ( maximum activity within 48 h) and returns 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.

58. 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 be  due 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:
Atypical clinical presentation (absence of chest pain)
If the patient presents some time after a suspected event.
Difficulty in interpreting ECG (Arrhythmia or previous MI).
If further MI is suspected few days of a previous one.

59. CK-2 & CK-3 in normal subject and in patient
24 hrs after Myocardial Infarction
Creatine Kinase isoenzymes in blood

60. Plasma levels following myocardial infarction
CPK---Creatine Kinase
LDH---Lactate Dehydrogenase
HBDH—α-Hydroxybutyrate dehydrogenase

62. Myocardial Infarction : Plasma Enzymes Changes
Duration of abnormality (days)
Peak value of abnormality(h)
Abnormal activity detectable(h)
Enzyme
3 - 10
CK-MB isoenzyme
2 - 5
5 - 12
Total CK
2 - 6
6 - 12
AST
5 - 14
8 - 16
Heart-specific’ LD

63. Myocardial Infarction : Plasma enzymes vs ECG
Specificity %
Sensitivity %
100 70
ECG 90 95
Plasma Enzymes

64. Troponin
Troponins are a complex of I, T and C subunits uniquely present in striated muscle and regulate the calcium 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 after infarction.
Better test than LDH and CKMB.

65. Malignant Hyperpyrexia
Muscle Diseases
Muscular Dystrophy
Toxic Myopathy
Malignant Hyperpyrexia
Traumatic Myopathy

66. Muscular Dystrophy Genetically determined degenerative disorders.
Duchenne muscular dystrophy is an X-linked recessive disorder caused by an abnormal dystrophin gene (progressive weakness of muscles).
CK activities before the onset of clinical symptoms (values >10 times the normal upper level).
Serum CK is in 75 % of female carriers.
Becker’s muscular dystrophy is a benign form of Duchenne MD.
CK elevated pattern similar to that of Duchenne MD.

67. Malignant Hyperpyrexia
Toxic Myopathy
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

68. Traumatic Myopathies
Muscle trauma (surgery, I.M. injection, etc..)  release of enzymes
High serum CK values occurs post-operatively .
If MI suspected, CK-MB should be measured.
Serum CK usually return to normal within 48 h of a single intramuscular injection.
Vigorous exercise of short duration and prolonged moderate exercise  serum CK

69. Liver Diseases Hepatic Necrosis Hepatitis Cholestasis Jaundice
Hepatocellular Damage

70. Liver Enzymes ( ALT, AST, GGT, ALP, LDH)
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 to  synthesis ( the values are 5-10 times the upper normal level) .

71. Bone Diseases
- Osteoporosis
- Osteomalacia
- Tumors
- Paget’s Disease

72. Bone Enzymes - ( Alkaline Phosphatase) ALP
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 Paget’s disease of bone    of ALP (10 times)
1ry & 2ry bone tumors   of ALP (5 times normal)

73. Enzymes in Urine Enzymes 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)

74. Enzymes in Hematological Disorders
Inherited or acquired diseases 
- Hemolytic diseases
- Spherocytosis
- Methemoglobinemia
 G-6-PD deficiency  Hemolysis on exposure to oxidant drugs as antimalarial drugs (Primaquine) or ingestion of fava beans
 Pyruvate kinase , Glutathione synthetase, Hexokinase Defects  Hemolysis

75. شكرًا لحسن المتابعة

76. Thank you

78. Enzymes Proteins. Increase reaction rates by lowering activation
energy.
Increase rates by
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 DG.

90. Some other Enzymes of Diagnostic Value
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

92. Factors affecting serum enzyme concentrations
1.    Rate of entry
         - tissue damage   enzyme synthesis
         - extent of tissue damage
         - concentration gradient
        - rate of production
 2.   Rate of clearance
        - breakdown by proteases
         - removal by reticuloendothelial system
        - renal excretion only for amylase (small molecular weight)
 3.   Induction
 4.   Proliferation

94. Functions of Released Enzymes
Components of bone—Collagen, Hyaluronic acid, Sulfated glycoproteins, Hydroxyapatite
Hyaluronic Acid NAG + Glucuronic Acid HU
Sulfated Glycoproteins NAG sulfate + Glucuronic
AS, CS Acid
Acids produced breakdown the hydroxyapatite crystal lattice

95. Bone Resorption Bone Collagen type I Abnormal Hydroxyapatite Crystal
lattice
Collagenase type I
¾ and ¼ Chains
Neutral Proteinase
Amino acids and peptides