Glutamate Oxaloacetate Transaminase (GOT) is an enzyme, a type of protein that facilitates chemical reactions within the body, though it is now more commonly called Aspartate Aminotransferase (AST). An AST test measures the quantity of this enzyme in the bloodstream. While small amounts of AST are normally found in the blood, if tissues containing the enzyme are damaged, AST is released, leading to higher concentrations.
The Role of GOT in the Body
Glutamate Oxaloacetate Transaminase, or GOT, is involved in the metabolism of amino acids, the building blocks of proteins. The enzyme helps synthesize and break down these molecules, a process that allows the body to generate energy and build new proteins as needed.
This enzyme is present in various tissues throughout the body. The highest concentrations are found in the liver, with significant amounts also located in the heart, muscles, kidneys, and brain. The widespread distribution of this enzyme means its presence in the bloodstream can signal issues across different organ systems, though it is most closely associated with liver health.
The GOT Blood Test
A physician may order a GOT/AST test as part of a routine comprehensive metabolic panel (CMP) or a more targeted liver function test (LFT). The test may also be ordered if a person shows symptoms of a liver condition, such as jaundice, fatigue, or abdominal swelling. It serves as a tool to help diagnose, monitor, or assess the severity of liver diseases.
Generally, no special preparation is needed for the test, though a healthcare provider might instruct a patient to fast for a certain period before the blood draw. It is also important for patients to inform their doctor of any medications or supplements they are taking, as some substances can influence the test results.
Interpreting Test Results
Interpreting AST test results involves comparing the measured enzyme level to a standard reference range. Elevated levels are a general indicator that cells in an organ have been damaged. Since the liver contains the highest concentration of AST, high levels frequently point toward liver injury or disease, such as hepatitis, cirrhosis, or liver damage from toxins.
What is considered a “normal” range can vary between laboratories due to different equipment and testing methods. For example, one common reference range is 8 to 33 units per liter (U/L), but this is not universal. Patients should always refer to the specific range on their lab report and discuss the findings with their healthcare provider for an accurate interpretation.
Low levels of GOT/AST are uncommon and not a cause for medical concern. In some rare cases, they might be associated with conditions like a vitamin B6 deficiency or certain kidney diseases, but this is not a primary diagnostic use of the test.
Medical Conditions Associated with Abnormal Levels
A variety of medical conditions can cause elevated AST levels, with liver-related issues being the most common, including:
- Viral hepatitis
- Alcoholic liver disease
- Non-alcoholic fatty liver disease
- Cirrhosis
Conditions that reduce blood flow to the liver or the presence of a liver tumor can also raise AST levels. Extremely high levels, sometimes over 1,000 IU/L, might suggest acute conditions like drug-induced liver injury from a paracetamol overdose.
Beyond the liver, other conditions can also lead to abnormal results. A heart attack can cause a spike in AST as heart muscle cells are damaged. Muscle injuries, including trauma or diseases like muscular dystrophy, are also known to increase AST levels. Other less common causes include pancreatitis, deep burns, and recent seizures or surgery.
To better pinpoint the source of the damage, doctors often analyze the AST level in conjunction with another liver enzyme, Alanine Aminotransferase (ALT). The AST/ALT ratio can offer diagnostic clues. For instance, an AST/ALT ratio greater than 2:1 is highly suggestive of alcoholic liver disease, while most other forms of liver injury are associated with a higher ALT level compared to AST.