Aspartate Aminotransferase (AST)

To sum it up, picture AST as a builder that removes pieces from one structure to help create another

structure. AST levels are measured alongside of alanine aminotransferase (ALT; another type of enzyme)

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

pulmonary elbolism.

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

sample.

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.