What is aspartate transferase (AST)?
Aspartate transferase (AST), also known as aspartate aminotransferase, is an enzyme that exists in your liver, heart, brain, pancreas, kidneys, muscles and many tissues in your body. Although it can be found throughout your body, AST is most commonly associated with liver health.
An enzyme is a type of protein in a cell that acts as a catalyst and allows certain bodily processes to happen. There are thousands of different enzymes throughout your body that have important functions.
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What is an AST blood test?
An AST blood test measures the amount of aspartate transferase in your blood. In most cases, your healthcare provider uses an AST blood test to help assess the health of your liver, but it can provide insight into other health conditions as well.
When your cells get damaged, AST can leak into your bloodstream. Because of this, high levels of AST in a blood sample can be a sign of an underlying medical condition — most often (but not always), a liver condition.
As many types of liver conditions can cause AST levels in your blood to rise, healthcare providers don’t use the test alone to diagnose conditions. An AST blood test is most often included in a blood test panel, such as a liver enzyme panel (HFP) or a comprehensive metabolic panel (CMP). A blood panel measures several aspects of your blood with one sample and can provide more detailed information about your overall health.
Common names for an AST blood test include:
- Aspartate transferase (AST).
- Aspartate aminotransferase (AST).
- Serum glutamic-oxaloacetic transaminase.
- SGOT.
- Aspartate transaminase.
How is aspartate transferase (AST) different from alanine transferase (ALT)?
Alanine transferase (ALT) is an enzyme that’s commonly measured along with AST in a liver function panel or comprehensive metabolic panel (CMP). Both these enzymes can leak into your bloodstream when certain cells in your body are damaged.
While both are known as liver enzymes, AST is found in more parts of your body than ALT. For this reason, higher-than-normal levels of ALT tend to be a more specific indicator of liver conditions than higher-than-normal AST levels. However, your healthcare provider will usually review both these levels together when assessing the health of your liver.
Why do I need an AST blood test?
The purpose of an AST blood test is to detect damage to cells. If cells in your liver are damaged, it can cause AST to leak into your blood, so an AST blood test can help find liver issues. While your healthcare provider will most often use the test to help assess liver health, an AST test can also provide information for other medical conditions and cell damage elsewhere in your body.
Your healthcare provider may order a blood panel test that includes an AST test for you to help screen for, monitor or help diagnose liver conditions and other medical conditions.
Screening
Screening means checking for potential health issues before you experience symptoms. Your healthcare provider will likely recommend screening with a liver panel blood test that includes an AST test if you have risk factors for liver disease, including:
- Heavy alcohol use.
- Family history of liver disease.
- Diabetes.
- Obesity.
- Injecting drugs using shared needles.
Since AST tests are often included in routine blood panel tests that assess your general overall health, such as a comprehensive metabolic panel, you may get an AST test even if you don’t have risk factors for liver disease.
Monitoring
If you have a liver condition, your healthcare provider may order an AST test, often as part of a panel, to monitor your condition to see if it’s improving, worsening or staying the same with or without treatment. Your healthcare provider may also have you do an AST test and liver enzyme panel test if you’re taking a medication that can affect your liver.
Diagnosing
Your healthcare provider may use an AST test for diagnostic purposes when you’re experiencing signs and symptoms of possible liver problems. While healthcare providers can’t diagnose a condition based solely on AST levels, it can be an important part of the diagnostic process.
Signs and symptoms of liver conditions include:
- Nausea and/or vomiting.
- Belly (abdominal) pain.
- Itchy skin.
- Jaundice (a yellowing of your skin and the whites of your eyes).
- Tiredness (fatigue).
- Appetite loss.
FAQs
The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood. Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe.
What level of AST is concerning? ›
What level of AST and ALT is concerning? AST levels above 40 U/L can indicate liver inflammation, or damage to the heart, bones, or muscles. AST levels above 1,000 U/L may indicate liver injury or hepatitis. Doctors may consider ALT results high if they are above 33 U/L in males and above 25 U/L in females.
Why would a doctor order a AST test? ›
What is it used for? An AST blood test is often part of a routine blood screening to check the health of your liver. The test may help diagnose or monitor liver problems. It may also help diagnose other health conditions.
Should I worry about a low AST level? ›
Doctors suggest an AST blood test to assess liver health. Also this test provides other insight of other body parts too. Elevated AST levels affect other organs in the body like myocardial infarction, acute pancreatitis, acute renal disease etc. Lower levels of AST mean that the person has good health.
How do you fix AST levels? ›
The treatment for high AST levels depends on the underlying cause. If liver disease is identified, lifestyle changes such as alcohol cessation, weight management, and dietary modifications may be recommended. Medications and interventions specific to the diagnosed condition may also be prescribed.
Should I be worried if my AST and ALT are high? ›
There are many causes of mildly elevated ALT and AST levels. The most common causes are nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease. In NAFLD, the liver has more fatty tissue in it than normal. Regular or heavy alcohol use can also hurt the liver and increase liver enzymes.
Is 70 a high AST level? ›
Typically the range for normal AST is reported between 10 to 40 units per liter and ALT between 7 to 56 units per liter. Mild elevations are generally considered to be 2-3 times higher than the normal range. In some conditions, these enzymes can be severely elevated, in the 1000s range.
What will happen if AST is high? ›
A high AST level often means there is some liver damage, but it is not necessarily caused by hepatitis C. A high AST with a normal ALT may mean that the AST is coming from a different part of the body. It is important to realize that the AST level in most patients with hepatitis C goes up and down.
Is ALT 90 need for concern? ›
An ALT test result of >100 IU/l is a clear indicator of serious liver disease, but a mildly elevated ALT result (30–100 IU/l) is often ascribed to the use of medication (for example statins) or alcohol, obesity, or, for lower ALT levels (<50 IU/l), considered as part of the normal distribution of test results.
When to worry about ALT levels? ›
High levels of ALT in your blood can be due to damage or injury to the cells in your liver. An increased ALT level may indicate the following conditions: Alcohol-induced liver injury. Fatty liver disease (too much fat in your liver).
Causes of low AST: uremia, vitamin B6 deficiency (this can be corrected), metronidazole, trifluoperazine. Causes of high AST: chronic alcohol ingestion, not limited to overt chronic alcoholism; cirrhosis. In alcoholic hepatitis, AST values usually are <300 units/L.
Why would AST levels drop? ›
But there are cases when low AST levels can be caused by: Uremia (urinary waste in your blood) Vitamin B6 deficiency. Some medications, including metronidazole (Flagyl) and trifluoperazine (Stelazine)
What causes liver enzymes to be low? ›
There's only one major clinical scenario where low liver enzymes is a concern, and that's in end stage liver disease or liver cirrhosis, where the liver has become so filled with scar tissue that there's no longer really enough liver cells to produce any of those enzymes.
What should I eat if my AST is high? ›
AST and ALT levels can be lowered by consuming certain foods that promote liver health. These include garlic, turmeric, leafy greens, cruciferous vegetables, and berries, which contain specific compounds or antioxidants that support liver function.
What is the normal range of AST by age? ›
Adults: 0-35 units/L or 0-0.58 μKat/L (SI units) (Values tend to be slightly lower in females than males.) Elderly: Values are slightly higher than those of other adults. Children : 0-5 days: 35-140 units/L.
What is a critical high AST? ›
Very high AST levels (greater than 500 units/L) can be caused by: Acute viral hepatitis. Large liver tumors. Severe liver damage from drugs or toxins. Shock liver (damage from lack of oxygen or blood flow)
What is an alarming ALT level? ›
An ALT test result of >100 IU/l is a clear indicator of serious liver disease, but a mildly elevated ALT result (30–100 IU/l) is often ascribed to the use of medication (for example statins) or alcohol, obesity, or, for lower ALT levels (<50 IU/l), considered as part of the normal distribution of test results.
Is ALT 70 need for concern? ›
Usually, the upper limit of ALT is 35 - 40 U/L. Moderate increase in ALT (such as 70 U/L) is seen in chronic hepatitis, chronic obstruction of bile ducts, heart damage, alcohol abuse, liver tumor, skeletal muscle damage. In any acute liver conditions, ALT is much more elevated.
What is the ALT AST ratio for cirrhosis? ›
2.1 AST/ALT ratio
Subsequently, a number of studies found that the ratio > 1.00 suggested cirrhosis in patients with chronic viral hepatitis, non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD) and primary biliary cirrhosis (PBC) [10–14].
