Alt and AST role in liver disorder

ALT is an enzyme present in liver, heart skeletal muscles, highest concentration is present in Liver. it value increases when there is abnormality in liver, ALT is an amino transferase which transfer one amino group from an amino acid and transfer to another substance for production of non essential amino acid

1. Muhammad Asif Zeb
Lecturer MLT
IPMS,KMU

2. Measurements of the activity of enzymes in plasma
are of value in the diagnosis and management of a
wide variety of diseases.

4. Small amounts of intracellular enzymes are present
in the blood as a result of normal cell turnover.
When damage to cells occurs, increased amounts of
enzymes will be released and their concentrations
in the blood will rise.

5. However, such increases are not always due to
tissue damage.
Other possible causes include:
increased cell turnover
cellular proliferation (E.g. neoplasia)
increased enzyme synthesis (enzymes induction)
obstruction to secretion

6. Enzyme assays usually depend on the measurement
the catalytic activity of the enzyme, rather than the
concentration of the enzyme protein itself.
One international unit is the amount of enzyme that
will convert one micromole of substrate per minute
per litre of sample and is abbreviated as U/L.

7. A major disadvantage in the use of enzymes for the
diagnosis of tissue damage is their lack of specificity to
a particular tissue or cell type.
 Many enzymes are common to more than one tissue.

9. Alanine transaminase or ALT is a transaminase enzyme (EC
2.6.1.2).
 It is also called serum glutamic pyruvic transaminase (SGPT)
or alanine aminotransferase (ALT).
ALT is found in serum and in various body tissues, but is most
commonly associated with the liver.

10. It is the reaction between an amino acid and an alpha-keto acid.

The amino group is transferred from the former to the latter;
this results in the amino acid being converted to the
corresponding α-keto acid, while the reactant α-keto acid is
converted to the corresponding amino acid.
 Transamination in biochemistry is accomplished by enzymes
called transaminases or aminotransferases.
This process is an important step in the synthesis of some non-
essential amino acids (amino acids that are not supplied from
the diet).

11. More specifically, AST, ALT, and alkaline phosphatase
are called the liver enzymes and they typically are
used to detect damage or injury to the liver (not its
function).

12. ALT is exclusively in cytoplasm of many tissue like
liver, heart, kidney, lungs.
But highest concentration is present in liver.

14. It is commonly measured clinically as a part of a
diagnostic liver function test, to determine liver health.

Diagnostically, it is almost always measured in units/liter
(U/L).
Normal level in serum:
ALT < 45 units/ml

15. Elevated levels:
 Viral or autoimmune hepatitis.
Cirrhosis.
Lack of blood flow to the liver (liver ischemia).
Death of liver tissue (liver necrosis).
Liver tumor.
Use of drugs that are poisonous to the liver.
Biliary duct problems.
For this reason, ALT is commonly used as a way of screening
for liver problems.

16.  When elevated ALT levels are found in the blood, the
possible underlying causes can be further narrowed down by
measuring other enzymes.
For example, elevated ALT levels due to liver-cell damage can
be distinguished from biliary duct problems by measuring
alkaline phosphatase.

17. The Alanine Transaminase (ALT) spectrophotometric assay
uses enzymatic reaction:
GPT
L-Alanine + α-ketoglutaric acid L-Glutamic acid + Pyruvic
LDH
Pyruvic acid + NADH + H+ L-Lactic acid + NAD+
The absorbance is measured at 505 nm, is proportional
to the level of ALT enzyme in the sample.

18. Why Get Tested?
To screen for liver damage and/or to help diagnose
liver disease.
Sample Required?
Serum.
When is it ordered?
To evaluate a person who has symptoms of a liver disorder:
 Weakness, fatigue, Loss of appetite
Nausea, vomiting
Abdominal swelling and/or pain
Jaundice
Dark urine, light colored stool
Itching (pruritus)

19. What does the test result mean?
Very high levels of ALT (more than 10 times the
highest normal level) are usually due to acute
hepatitis, often due to a virus infection.
In acute hepatitis, ALT levels usually stay high
for about 1–2 months but can take as long as 3–
6 months to return to normal.
ALT levels are usually not as high in chronic
hepatitis, often less than 4 times the highest
normal level.

20. Other causes of moderate increases in ALT
include obstruction of bile ducts, cirrhosis and with
tumors in the liver.
In most types of liver diseases, the ALT level is
higher than AST.

21. Aspartate transaminase (AST) also called
serum glutamic oxaloacetic transaminase
(SGOT) (EC 2.6.1.1) is similar to alanine
transaminase (ALT) in that it is another enzyme
associated with liver parenchymal cells.

23. Two isoenzymes are present in humans.
GOT1, the cytosolic isoenzyme derives mainly
from red blood cells and heart.
GOT2, the mitochondrial isoenzyme is
predominantly present in liver.
Normal Level:
AST <40 units/ml

24. It is raised in acute liver damage. It is also
present in red blood cells and cardiac muscle,
skeletal muscle and may be elevated due to
damage to those sources as well.
AST was defined as a biochemical marker for
the diagnosis of acute myocardial infarction
in 1954. However the use of AST for such a
diagnosis is now redundant and has been
superseded by the cardiac troponins.
AST (SGOT) is commonly measured clinically
as a part of diagnostic liver function tests, to
determine liver health.

25. Glutamic-Pyruvic Transaminase (GPT) is found in
significant quantities in liver, kidney, and skeletal
muscle, in decreasing order.
When liver cells are damaged, GOT and GPT levels
rise especially early in the disease.
In hepatitis, transaminase levels rise several days
before jaundice begins.
The enzyme levels are especially useful in assessing
subtle and early changes in biliary obstruction and
active cirrhosis.

26. Principle:
GOT
L-Aspartate + α-ketoglutarate L-Glutamate + Oxaloacetate
The oxaloacetate obtained is measured in its derative from
2,4 dinitropheny hydrazone.
The absorbance is measured at 505 nm, is proportional to
the level of ALT enzyme in the sample.

Sample:
Serum.

27. Glutamic-Oxaloacetic Transaminase (GOT) occurs
in large concentrations in the heart and liver with
moderate amounts in skeletal muscle, kidneys, and
pancreas.
GOT levels can be used to diagnose myocardial
infarction within 10-48 hours. Other conditions with
elevated GOT include arrhythmias and severe
angina of the heart, and liver damage.