Test Quick Guide

Aspartate aminotransferase (AST) is an enzyme, a type of protein that enables most bodily processes. AST exists mostly in the liver, but it is found in numerous tissues in the body.

When cells become damaged, AST can be released into the bloodstream. For this reason, abnormal levels of AST in a blood sample can indicate an underlying problem.

Although AST can be measured alone, it is usually included with other enzymes as part of broader tests, such as a liver panel or comprehensive metabolic panel (CMP). When interpreted alongside other enzymes, an AST measurement can help identify liver disease and other health issues.

About the Test

Purpose of the test

A blood test measuring AST is used to detect damage to cells. Most often, it helps assess the condition of the liver, but it can provide insight into other health concerns as well.

Depending on the situation, AST testing, usually combined with other measurements in a panel test, can be used as a form of medical screening, diagnosis, or monitoring:

  • Screening is the medical term for testing when you don’t have any symptoms of a condition. A screening that includes AST may be prescribed if you have risk factors for liver disease such as obesity, diabetes, significant alcohol use, or a family history of liver problems. During routine health checkups, AST may also be tested on a CMP.
  • Diagnosis takes place after symptoms have occurred and is the process of finding the cause. For example, AST may be measured if you have had jaundice, fatigue, swelling, unexplained weight loss, itching, nausea and vomiting, or other symptoms associated with liver problems.
  • Monitoring describes the steps taken to see how your health situation evolves. Sometimes, you may have repeated tests that include AST at frequent intervals to track your liver health. AST can be measured to help determine how well treatment for liver problems works. A panel test with AST can also check for signs of liver damage if you start taking a medication that could potentially affect your liver.

What does the test measure?

This test measures the level of AST in your blood. AST is an enzyme normally present in the liver, heart, brain, pancreas, kidneys, and many other muscles and tissues in the body. Enzymes like AST help facilitate fundamental biological processes in these organs and tissues.

It is common for AST to be measured as part of a panel of other enzymes and proteins in the blood because it may give your doctor a better view of your overall condition compared to only evaluating the AST test result.

When should I get this test?

A measurement of AST in your blood may be beneficial in several different medical situations. If you have symptoms of liver disease, a panel test that includes AST can help assess the cause and determine the severity of the problem.

Tests that measure AST like the liver panel and the CMP are often used as diagnostic tests if you have to go to the emergency room or have general symptoms that could cause many health problems.

Testing your levels of AST can be appropriate as a form of screening, especially if you are at high risk of liver problems. Some doctors prescribe AST testing during normal checkups even if you don’t have risk factors for liver disease. Despite this, there is no clear medical evidence showing that this broad approach to screening generates more benefits than drawbacks, which can include increased costs and unnecessary follow-up tests.

An AST test may be utilized for monitoring if you have previously had an abnormal test result or a diagnosed liver disease. If you begin taking a new medication that can affect the liver, your doctor may prescribe a lipid panel with an AST measurement to monitor for possible side effects.

Finding an Aspartate Aminotransferase Test

How can I get an aspartate aminotransferase test?

Tests for AST are usually prescribed by a doctor and conducted in a doctor’s office, hospital, or laboratory, where blood is drawn from a vein in your arm. Results are determined through laboratory analysis of your blood sample.

Can I take the test at home?

While most AST testing is done with a blood draw in a medical setting, somas little as $29e at-home tests include a measurement of AST in a panel along with other enzymes and proteins. After taking a blood sample at home, you mail it to a laboratory. You then receive results by mail, with a smartphone app, or through an online portal.

How much does the test cost?

The cost of an AST test can vary depending on where the test sample is taken, whether other measurements are included, whether you have medical insurance, and whether your insurance covers the test.

Several charges may be associated with an AST test or a panel test that includes AST. For example, separate fees may be charged by the technician who draws your blood, the lab that does the analysis, and the doctor’s office which prescribes the test or reviews the results with you.

If your doctor recommends the test, many of these charges are partially paid for by insurance. But check with your doctor and insurance company to find out if your test will be covered and if you are responsible for any copayment or deductible.

At-home tests that include AST can vary in price based on how many different measurements are taken. Tests are often available for around $100, which includes the test kit, shipping, laboratory analysis, and results.

Taking an Aspartate Aminotransferase Test

Testing AST requires a sample of blood. Blood is obtained through a venipuncture procedure using a needle inserted into a vein in your arm.

At-home tests for AST also rely on a blood sample; however, they utilize a fingerstick instead of venipuncture. This means that you prick your finger to obtain a drop of blood. This sample is then mailed to a laboratory where it can be tested for its level of AST.

Before the test

Because AST is usually measured with other enzymes and compounds, you typically need to fast before your blood is drawn. This means that you consume no food and no beverages other than water. You may need to fast up to 12 hours before the test, but check with your doctor’s office for specific instructions.

If you are being tested for only AST, you usually do not need to fast or take other special precautions before the test.

Various types of medications can influence levels of AST and other liver enzymes, so talk with your doctor before the test about any prescription drugs, over-the-counter medications, or dietary supplements you take regularly.

During the test

When you go for a blood draw, you will be seated, and a stretchy band will be tied tightly around the upper part of one arm so that there is greater blood flow in that arm. The technician will use an antiseptic to clean the puncture site and then insert a needle into your vein to withdraw a vial of blood.

Once the necessary amount of blood is drawn, the needle is removed. The whole process is usually over within a few minutes. You may experience a sting or other pain from the needle puncture.

You will need to read and follow the instructions in your test kit for an at-home test. In most cases, you will use an antiseptic to clean your fingertip and then use a small needle included in the kit to lightly prick your finger. A drop of blood is placed on a special test paper, which you then seal and put in the mail.

After the test

After a blood draw, a small bandage will be placed on your arm to apply pressure and stop further bleeding. You may have some bruising or discomfort, but it is rare for there to be any serious side effects.

If you were instructed to fast before the test, you may want to bring a snack to eat once the test is over. After the test, you can return to most normal activities, including driving.

Side effects are also uncommon after an at-home test. If needed, you can use a bandage to stop continued bleeding from your fingertip.

Aspartate Aminotransferase Test Results

Receiving test results

You should receive results with your AST levels within a few business days after your blood draw. A test report may be available to access electronically or sent to you by mail. Your doctor’s office may also call you to provide results.

And if you take an at-home AST test, the kit must be sent by mail to a laboratory to analyze it. As a result, it may take an extra few days to get results, which are usually provided electronically.

Interpreting test results

AST levels are usually listed on your test report in units per liter (U/L) or international units per liter (IU/L). Next to the level found in your blood, the test report should list the laboratory’s reference range.

It is important to look closely at the range for the specific lab that analyzed your sample because there is no universal reference range for AST. Ranges can vary because not all labs use the same methods, and studies have not demonstrated a precise healthy range.

In addition, no AST level is normal for all people. Instead, a healthy AST level can change depending on your age, sex, race, weight, and other factors that your doctor can consider when interpreting your test result.

To understand the significance of your results, your doctor often looks at AST and the levels of other enzymes included in a liver panel test. Patterns in which enzymes are normal or abnormal can offer meaningful clues about an underlying problem.

Because AST levels in the blood can rise when cells are damaged, elevated AST can reflect health conditions, including liver diseases like cirrhosis or hepatitis. To determine the cause of an abnormal result, the doctor may consider how high the AST level is and how it compares to the levels of other liver enzymes.

Very high levels of AST often reflect short-term liver damage, while smaller but persistent elevations in AST over time can be tied to chronic conditions. However, because AST is found in other body parts, it can be elevated in the blood due to cell damage outside the liver.

For this reason, the doctor may look at the levels of both AST and the enzyme alanine aminotransferase (ALT) side by side. ALT is more concentrated in the liver, so if AST is high while ALT is normal, it can indicate a problem outside the liver. In other cases, though, having a much higher level of AST than ALT can be a sign of alcohol-induced damage to the liver.

It is also important to note that having elevated AST is not proof of a medical problem. If you are healthy with proper liver function, you may still have an AST level outside the normal range, which can occur based on individual factors like age, sex, race, diet, exercise, or having taken medications that can affect AST.

Because of the complexity of interpreting AST levels, including their relationship to other measurements on a panel test, always discuss your test result with a doctor who can explain what the test means and how it reflects your overall health.

To best understand the meaning and interpretation of your AST test, you can ask some of the following questions when discussing your test with your doctor:

  • What is the reference range for AST for the laboratory that did my test?
  • Were my AST levels normal or abnormal?
  • Did the test measure anything in addition to AST? Were any of those levels abnormal?
  • What is the most likely explanation for my AST level?
  • Should I repeat this test or take other tests as a follow-up?


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