AST is also found in certain body tissues, especially the heart and the liver. The liver is
the largest organ in the body and is responsible for filtering (removing) harmful chemical
substances, producing important chemicals for the body, and other important functions.
AST is also found in the pancreas (a long organ at the back of the belly) and muscle
WHAT DOES ASPARTATE AMINOTRANSFERASE SPECIFICALLY DO?
AST helps to form an acid known as oxaloacetic acid and an amino acid known as
glutamic acid. Amino acids are groups of chemical substances that form proteins.
Proteins are extremely complex, naturally occurring substances made of amino acids that
are essential to the body's structure and function.
HOW DOES AST DO ITS JOB?
AST helps create the substances mentioned in the previous section
by causing a chemical reaction. The chemical reaction is caused by
moving molecules from aspartic acid (a type of amino acid) to alpha-
ketoglutaric acid (a type of acid). This reaction is reversible,
however. Molecules are the smallest naturally occurring particles of
a substance. See the previous section for a definition of amino
acid. The molecules that AST move are called amino groups. Amino
groups are part of amino acids. They are made up of one part
nitrogen and two parts hydrogen. Nitrogen and hydrogen are both
To sum it up, picture AST as a builder that removes pieces from one structure to help create another
levels to assess liver functioning.
WHAT IS THE NORMAL LEVEL OF ASPARTATE AMINOTRANSFERASE IN THE BLOOD?
The normal range of AST on blood work tests is 8 to 35 units per liter (U/L) or 5 to 40 International Units
per liter (IU/L). However, it is important to keep in mind that these ranges will be different depending on the
machine used to do the blood test. Always use the normal range printed on the lab report to decide what
range is normal. Regarding the way in which these ranges are measured, a unit is a specific amount of a
substance that is needed to produce a desired effect. A unit's value will differ for each type of substance.
An International Unit is very similar to a unit but is based on a different type of scale. The value of an
International Unit will also differ for each type of substance. A liter is a measurement of the amount of
space that a liquid takes up in a container, which is equal to 1.056688 quarts. To understand this better,
picture a gallon of milk. It takes 4 quarts of milk to make up one gallon of milk. Since one liter is a little bit
more than one quart, 4 liters of milk is a little bit more than one gallon of milk.
WHAT CAN CAUSE THE LEVEL OF ASPARTATE AMINOTRANSFERASE TO BE TOO HIGH?
To begin with, since there are many reasons why AST levels can be high it is important that additional
testing is done to determine the exact cause. When an organ or body tissue is injured, increased levels of
AST are released into the blood. The greater the degree of tissue damage, the greater the degree of AST
that is released. Thus, liver damage, heart attack, heart surgery, or inserting a catheter into the heart can
cause levels of AST to increase. A catheter is a flexible, hollow tube that is inserted into an opening or
blood vessel in the body, with the main purpose of allowing fluid to pass from or into these areas. The liver
is the largest organ in the body and is responsible for filtering (removing) harmful chemical substances,
producing important chemicals for the body, and other important functions.
If the AST levels are 10 to 20 times higher than the normal range, chances are that the cause is a severe
heart attack, recent or severe liver damage, shock, or a large decaying tumor (a type of abnormal tissue).
Recent liver damage can be caused by a drug overdose. Severe liver damage can be caused by viral
hepatitis (an infection of the liver that causes liver inflammation). The liver is the largest organ in the body
and is responsible for filtering (removing) harmful chemical substances, producing important chemicals for
the body, and other important functions.
If the AST levels are 5 to 10 times higher than normal, this can also indicate a heart attack, heart failure,
lung damage, kidney damage, a long-term liver disease, cancer, inflammation of muscle tissue, or
Duchenne's muscular dystrophy. Duchenne's muscular dystrophy is a condition present in childhood in
which leg and hip muscles continuously waste away. If the AST levels are 2 to 5 times higher than normal
this can indicate a heart attack, heart damage, liver damage due to too much alcohol, inflammation of the
pancreas (a long organ in the back of the belly), and hemolytic anemia. Hemolytic anemia is a condition in
which the red blood cells are destroyed earlier than they should be. A cell is the smallest, most basic unit
of life, that is capable of existing by itself. Red blood cells help carry oxygen to the blood.
When a disease first develops, AST levels can be high because this is when tissue damage is the most
severe. This is why decreasing levels of AST can indicate recovery from a disease. Other conditions that
can cause AST levels to be high are traumatic injuries, severe burns, heat exhaustion, heat stroke, and
Heat stroke is a severe and sometimes-deadly condition caused by failure of the body to regulate
temperature due to long exposure to the sun or heat. A pulmonary embolism is a blockage of an artery (a
type of blood vessel that carries blood away from the heart) that goes from the heart to the lungs (two
organs in the body that help people breathe). The blockage is due to a mass of blood, known as a blood
clot. The condition can be life threatening because it can lead to the inability to breathe.
Stressful exercise, muscle injuries, or muscle injections can cause increased AST levels. Eating
poisonous mushrooms can also cause AST levels to be high. Medications that can cause liver damage
may also lead to raised AST levels. Examples of such medications would be erythromycin (an antibiotic)
and birth control pills. Medications that lower cholesterol levels (such as Zocor and Pravachol) can
increase AST levels as well. Cholesterol is a waxy, fatty substance found only in animal tissues. Large
amounts of aspirin and vitamin A can cause AST levels to be too high. A vitamin is one of a group of
substances made up partly of carbon (an element) that are essential in small amounts for normal bodily
functioning and chemical processes in the body to take place.
HOW LONG DOES ASPARTATE AMINOTRANSFERASE REMAIN AT A HIGH LEVEL?
AST levels will rise 6 to 10 hours after severe damage to an organ or tissues. They typically remain high
for 6 days.
WHAT CAN CAUSE THE LEVEL OF ASPARTATE AMINOTRANSFERASE TO BE TOO LOW?
A low AST level can be caused by a deficiency in vitamin B6. A vitamin is one of a group of substances
made up partly of carbon (an element) that are essential in small amounts for normal bodily functioning and
chemical processes in the body to take place. A low AST level may also be due to long-term kidney
dialysis. Dialysis is a technique in which one is hooked up to a machine that performs the functions of the
kidneys, removing wastes and extra water from the blood. The kidneys are two organs located on each
side of the spine, behind the stomach. The kidneys filter (remove) wastes from the blood. Certain
medications can lower the AST level, such as trifluoperazine (also known as Stelazine, an anti-psychotic
drug) and metronidazole (also known as Flagyl, an antibiotic). Anti-psychotic drugs treat psychosis (a
mental disorder characterized by an impairment in the ability to understand reality). Antibiotics are
medications that treat infections.
WHAT CAN CAUSE ASPARTATE AMINOTRANSFERASE LEVELS TO BE INACCURATE?
Sometimes, there are factors that do not involve the patient that can cause the test results to be
inaccurate. These factors include rough handling, improper refrigeration, or contamination of the blood
WHAT ELSE IS ASPARTATE AMINOTRANSFERASE CALLED?
Aspartate aminotransferase is also known as glutamic-oxaloacetic transferase (GOT), serum glutamic-
oxaloacetic transferase (SGOT), aspartate transaminase, and glutamic-aspartic transaminase.