This document discusses the use of clinical enzymology in the diagnosis and prognosis of diseases. It begins by explaining how measurements of enzyme activity in body fluids dates back to the early 1900s and measurements in serum began in the 1920s-1930s. A key development was the observation in 1955 that aspartate rises after acute myocardial infarction, marking the beginning of using changes in intracellular enzyme levels in plasma to detect tissue damage. The document then focuses on the clinical significance and diagnostic values of several heart function enzymes and liver enzymes. It provides details on normal levels, behaviors in different conditions, and diagnostic utilities of enzymes like CPK, AST, LDH, GGT, histaminase, and pseudocholinesterase for heart issues and AST

1. ENZYMES IN
DIAGNOSIS AND
PROGNOSIS
GEETA JAISWAL
M.L.N. MEDICAL
COLLEGE
ALLAHABAD

2. Clinical Enzymology
1. Clinical enzymology is the application
of the science of enzymes in the
treatment and diagnosis of diseases.
2. Measurements of the activity of
digestive enzymes in the body fluids
as an aid to diagnosis dates back to
the early 1900s (Amylase in urine was
first studied by Wohlgemuth in 1908)

3.  3.Measurements of enzymes
activity in serum began in the
1920s and 1930s.
 4. The scientists who began
these studies were Kay, King,
Bodansky and Roberts in their
work on Alkaline phosphatase.

4.  5. In 1955 La Due, Wroblewski
and Karmen reported the rise of
Asparate after acute myocardial
infarction → from this period a
great stimulus was received in
the measurement of cellular
enzyme released into the
plasma as a consequence of
tissue damage.

5. This observation marked the
beginning of the modern phase of
diagnostic enzymology.
Clinical chemists are principally
concerned with changes in the
activity in serum or plasma
enzymes that are predominantly
intracellular.

6. CLINICAL SIGNIFICANCE
OF SERUM ENZYME
 To investigate and interpret changes
in serum enzymes for diagnosis.
 This happens to be presently the
most advancing field in clinical
Biochemistry.
 Enzymes in circulation are divided
into two groups.

7. (A) PLASMA SPECIFIC OR
FUNCTIONAL ENZYMES
 (B) PLASMA NONSPECIFIC
OR NON-FUNCTIONAL
ENZYMES

8. (A) PLASMA SPECIFIC OR FUNCTIONAL
ENZYMES
 These are normally present in plasma
and have specific functions to perform.
 They are synthesized in the liver and
enter circulation.
 Their levels fall on impairment of liver
or genetic disorder.
e.g. Lipoprotein lipase
Plasmin
Choline esterase
Ceruloplasmin

9. (B) PLASMA NON SPECIFIC OR NON-
FUNCTIONAL ENZYMES
These enzymes are either totally
absent or in very low concentration
in the liver, eg:
 Digestive Enzymes
 Secretary Enzymes
 Enzymes associated with metabolism
Constitutive enzyme (LDH,Transaminases
etc)

10. Enzymes in Diagnosis and
Prognosis
 Estimation of the activity of non-plasma
specific enzymes is very important for
diagnosis and prognosis of the disease
 Normal serum levels indicate a balance
between its synthesis and release in
routine cell turnover.
 Serum enzymes are used as markers to
detect cellular damage, which helps in
diagnosis.

11. Raised levels may be due to
1) Cellular damage
2) Increased rate of cell turnover.
3) Proliferation of cells.
4) Increased synthesis of
enzymes.
5) Treating patients with protein
anabolic drugs.

12. DIAGNOSTIC
SIGNIFICANCEProvides information on the nature and
extent of the disease
Helps in diagnosis : e.g. assay of CPK
helps in confirming MI even when ECG
changes are doubtful.
e.g. SERUM
MI GOT ↑ LDH↑
Pulmonary GOT Normal LDH↑
Embolism

13. Helps in ascertaining prognosis :
The progress of enzyme changing
process helps to ascertain the
response of drugs to disease.
Helps in Early Diagnosis or Detection
: When tissue changes in a disease
are not pronounced enough.

14. Units of Enzyme Activity
Enzyme units are never
expressed in terms of their
concentration (as mg or µg ) but
are expressed as activity.
To maintain uniformity world
over enzyme activity as units is
expressed according to the
I.U.B system as:-

15. International Unit (IU)
 I.U or System International SI is
The activity of enzyme which
transforms one micromole of
substrate per minute under optimal
conditions and at a defined
temperature is IU ml
IU / L = when one milli micro mole
of substrate is transformed

16. Katal Unit
 Katal Unit is a new unit.
 Abbreviation is KAT
It is the conversion of 1 mole
substrate per second
1 IU = 60 µ katal

17. CLINICAL SIGNIFICANCE
OF HEART FUNCTION
ENZYMES
Normal
serum level
Creatinine Phosphokinase (CK or
CPK)
4 –60 IU/L
Aspartate Transaminase (AST,
SGOT)
4 –17 IU/L
Lactate Dehydrogenase (LDH) 60 –250
IU/L

18. OTHER ENZYMES NOT SO
COMMONLY DONE FOR HEART
FUNCTIONS
γ glutamyl
Transpeptidase
10 –47 IU/L
Histaminase 0.12 –0.76
PU/ml

19. CREATININE
PHOSPHOKINASE (4 – 60
IU/L)
Creatine – P + ADP Creatine + ATP
CPK
Found in high concentration in
skeletal muscles, myocardia and
brain.
Sensitive measure for MI and Muscle
diseases.
Normal in liver disease

20. Behavior in MI
In MI serum values rise after
6 hrs.
Peak is reached between 24
– 30 hrs.
Magnitude of elevation,
greater than GOT and LDH.

21. SERUM GLUTAMATE
OXALDACETATE TRANSAMINASE
(SGOT OR AST. (4 – 17 IU/L)
OXALOACETATE + GLUTAMATE ASPARTATE + αKETOGLUTARATE
• Present in high concentrations in the myocardium
• Behaviour in MI
• Rises sharply in the first 12 hrs.
• Peak at 24 hrs.
• Normal within 3 – 5 days.

22. ASSESSMENT OF MI
THROUGH SGOT
LEVELS
350 IU/L → Fatal (Massive infarction)
150 IU/L → Associated with high mortality
50 IU/L → Low Mortality
• Abnormal level highest on the 2nd
Day.
• Elevated also in → Muscle disease and
Hepatic Diseases.

23. LACTATE DEHYDROGENASE
(60 – 250 IU/L)
Catalyzes the reversible conversion
of Pyruvic Acid Lactic Acid.
In acute MI, serum activity rises
within 12-24 hrs.
Peak at 48 hrs.
Normal from 8 – 14th
Day.
LDH levels persist even after CPK
and SGOT normalize.

24. LACTATE DEHYDROGENASE
(60 – 250 IU/L)
Acute MI, LDH levels may rise as high
as 1500 IU/L.
Enzyme in non-specific for myocardial
tissues as LDH is widely distributed in
body cells.
Co-existing disease process in other
organs may cause elevation e.g. :
Pulmonary infarction and renal
necrosis

25. ENZYME RISE BEGINS PEAK NORMAL
CPK 6 hrs. 24 – 30 hrs. 72 hrs (3 days)
SGOT
Rises sharply
1st
12 hrs.
24 hrs. 3 – 5 days
LDH Rise 12 – 24 hrs 24 – 48 hrs. 8 – 14 days

26. γ GLUTAMYL
TRANSPEPTIDASE
(10 – 4 IU/L MEN : 7 – 30 IU/L
WOMEN)
Transfer glutamyl group from one
peptide to the other.
Highest Tissue Activity → in kidneys
Relatively High Activity → in liver,
lungs, pancreas.
Heart normally has very little YGT.
Raised serum levels in Acute MI found
later between day 7 – 11.

27. Useful in detecting MI in later stages
Elevated levels also seen in
 Heaptobilliary disorders.
 Alcoholics, alcoholic cirrhosis.
 Pancreatic diseases.
 In Epileptic patients.
Not elevated in any form of bone
disorders.
Used to distinguish raised Alkaline
phosphatase – associated with either
bone or hepatic dysfunctions.

28. HISTAMINASE
(0.12 TO 0.76 P.U
/ml)
Found raised in heart muscles.
Rises within 6 hrs of MI.
Helps in early diagnosis of MI
when ECG changes do not reveal
anything.
0.8 p.u/ml is raised, 3.4 to 4
→fatal.

29. PSEUDOCHOLINESTERASE
(2.17 TO 5.17 IU/ml)
• They hydrolyze cholinesters → choline.
• Two types of cholinesterases are present.
(a) True cholinerterase → Muscular tissue,
nerve tissue,RBC.
(b) Pseudo cholinesterase → Heart, Intestine,
Plasma.
• Provide a sensitive index for determining cellular
necrosis in the myocardium.
• Raised levels as early as 3 hrs and within 12 hrs.
• Levels decrease in Hepatitis and
Organophosphorus Poisoning.

30. SERUM ENZYMES IN LIVER
DISEASES
Liver functions can be ascertained by a
large numbers of enzymes.
They are divided into 2 groups
I) Most commonly and routinely done in
the laboratory.
II) Not routinely done in the laboratory.

31. Most commonly and
routinely done in the
laboratory.
a) Serum Transaminases
b) Serum Alkaline
Phosphatase

32. II) Other enzymes not done
routinely
a) Serum 5' nucleotidases
b) Serum LDH
c) Serum Isocitrate dehydrogenase
d) Serum Cholinesterase
e) Ser Ornithine Transcarbamylase
f) Serum Leucine Amino peptidase
g) Ser Hydroxybutyrate Dehydrogenase
η) γ Glutamyl Transpeptidase

33. SERUM ENZYMES IN
LIVER DISEASES
SERUM TRANSAMINASES
SGOT – 4 - 17 IU/L
SGPT – 3 - 15 IU/L
SERUM ALKALINE PHOSPHATASE
3 to 13 K.A/100ml
or 23 to 93 IU/L
SERUM 5’ NUCLEOTIDASES 2 – 17 IU/L
SERUM LDH 60 – 250 IU/L

34. SERUM TRANSAMINASE
Both the enzymes are present in
most tissues but relative amounts
vary.
Heart Muscles are rich in SGOT.
SGOT (AST) → 4 to 17 IU/L (7-35 units /ml)
SGPT (ALT) → 3 to 15 IU/L (6-32 units /ml)

35.  Liver Tissues are rich in SGPT.
 In liver disease both
transaminases are raised but
SGPT shows much higher values.
 Their determination is of extreme
use in assessing the severity and
prognosis of parenchymal liver
diseases

36.  It is the most sensitive diagnostic
index.
 The increase can even be such in the
prodromal stage, when jaundice has
not clinically appeared.
 In infective hepatitis values as high as
1000 units have been observed.
SGPT IS Used as screening test in the
outbreak of infective hepatitis viral
hepatitis.

37.  High values of SGPT are also
obtained in, though the increase is
comparatively less.
i. Toxic hepatitis – due to CCl4 poisoning
II. Hepatitis due to drugs – Chlorpromazine
 In obstructive Jaundice
(extra hepatic) – values increase
not above 200 –300 IU/L.
 Determination is effective in
differential diagnosis of Jaundice.

38. SERUM ALKALINE
PHOSPHATASE (3 –13
KAU/100 ml ; 23 –92 IU/L)
Found in a number of organs; Most
plentiful in Bones and Liver.
Present also in small intestine, kidney
placenta.
 Used for many years in the differential
diagnosis of Jaundice.
Raised levels are seen in both –
infectious hepatitis (viral); Post hepatic
Jaundice (extra hepatic obstruction).

39.  In obstructive Jaundice raised ALK
phosphatase level is much higher.
 Values higher than 35 KA units are
suggestive of obstructive Jaundice,
where ALP rises up to 200 KAU.
 35 KAU is the dividing line on the basis
of which by the assay of ALP differential
diagnosis between infectious hepatitis
and obstructive Jaundice can be made.

40.  Very high levels of ALP are also found
in : -
i) Xanthomatous biliary cirrhosis (in
which there is no extra-hepatic
obstruction.
ii) Space occupying lesions of liver.
a) Abscess
b) Primary carcinoma (Hepatoma)
c) Metastatic carcinoma
d) Infiltrative lesion, Like lymphoma
e) Granuloma and amylodotis

41. ALP assays differentiate
Cholestatic Jaundice is
Characterized by High ALP low
amino Transferase.
 Non-Cholestatic Jaundice →
converse occurs.

42. II . OTHER ENZYMES (not
done routinely)
I. Serum 5' Nucleotidases ( 2 –
17 IU/L)
 This enzyme hydrolyses nucleotides
with a phosphate group on carbon
atom 5' of ribose.
 Raised along with serum ALP in Liver
disease.
 Post hepatic jaundice raised up to 100
units.
 In bone diseases nucleotidases are
normal where as SALP is raised e.g.
Paget’s diseases.

43. II. Serum Lactate
Dehydrogenase (LDH) 70 – 240
IU/L
 Increased activity is found
particularly in infectious hepatitis.
 The increase is not as great as the
transaminase and its behaviour is
less predictable as the enzyme
increases in other diseases as well,
like leukemia, pernicious anemia,
megaloblastic and haemolytic
anemia in renal diseases and

44. III. Serum Iso-citrate Dehydrogenase
(ICD) (Normal range 0.9 to 4.0 IU/L)
In liver diseases – A marked increase in ICD
activity whether it is inflammatory like
infectious hepatitis, malignancy or from
drugs.
Large increase in infectious hepatitis –
Serum activity normal on 3rd
day.
In obstructive Jaundice – Normal value.
Liver Cirrhosis – Serum activity normal or
slightly raised.

45. IV. Serum Cholinesterases
(Normal value 2.17 to 5.17 IU/mL)
 They are enzymes which hydrolyze esters of
choline.
To give Choline and acetyl units
They are of two types
1. True cholinesterases (present in nerve
tissue and RBC)
2.Pseudocholinesterases (present in liver, heart,
muscles, intestine).

46. Pseudocholinesterases
Formed in the Liver
Serum activity is reduced in liver
cell damage and advanced cases
of liver cirrhosis.
Normal activity in obstructive
Jaundice

47.  First enzyme of Urea cycle catalyzing
Ornithine + Carbonyl P ⇔ Citrulline + PO4
Elevated markedly in viral hepatitis (10 –
200 fold), depending on the severity.
Slight elevation in Obstructive Jaundice.
V. Serum Ornithine Carbamyl
Transferase (OCT) (8 – 20IU/L)

48. It is a Proteolytic enzyme which splits N –
terminal residues from certain L –
peptides.
Viral Hepatitis –
mild to moderate increase – 30 –130 m
IU.
Obstructive Jaundice –
Marked increase, more in malignant
obstruction than benign.
- Benign obstruction – 75 to 184 IU
- Malignant obstruction – 67 to 340 IU
VI. Serum Leucine amino peptidase
(LAP 15 – 56 m IU

49. VII. Serum Hydroxy Butyrate
Dehydrogenase (SHBD – 56 –125 IU/L)
• This enzyme acts on α -OH Butyric
Acid.
• Elevated levels in acute viral hepatitis.

50. VIII. Serum γ Glutamyl Transferase (γ
GI) Normal – 10 –47 IU/L
• Recently the importance of this enzyme in
alcohol abuse has been stressed.
• The activity of this microsomal enzyme has
been found to increase in heaptobilliary
diseases, but unlike aminotransferases
elevated levels do not necessarily indicate
liver cells disruption, but may be due to
enzyme induction by drugs such as
phenobarbitons, phenytoin and alcohol

51. • Severe limitations have meant that this
test now has only two practical uses.
(a) An elevated γ GT implies, that elevated
ALP is of hepatic origin
(b) Useful in screening alcohol – Sudden
increase in γ GT in chronic alcoholics
suggest recent drinking bout of drinking
alcohol.