AST Test

An AST blood test measures the amount of AST in your blood. This test is commonly used to help diagnose liver damage or disease. AST (aspartate aminotransferase) is an enzyme, a protein that speeds up certain chemical reactions in your body.

It is found mainly in your liver but also in your heart, muscles, and other tissues. Usually, you will have low levels of AST in your blood. When your liver or other cells that contain AST are damaged, they release AST into your blood.

This can lead to high AST levels in your blood. An AST test may be ordered by itself but is often ordered as part of a group of liver function tests.

Why this test is done

You may get an AST blood test as part of your routine checkup or to monitor the treatment of a liver problem. You may also need a test if you have symptoms of liver damage, which may include:

• Nausea and vomiting
• Lack of appetite
• Fatigue
• Weakness
• Jaundice, a condition that causes your skin and eyes to turn yellow
• Swelling and/or pain in your abdomen (belly)
• Swelling in your ankles and legs
• Dark-colored urine (pee) and/or light-colored stool (poop)
• Frequent itching

Even if you don't have symptoms, your health care provider may order an AST blood test if you're more likely to develop liver disease because of:

• A family history of liver disease
• Alcohol use disorder (AUD)
• Obesity
• Diabetes
• Taking certain medicines that can cause liver damage
• Hepatitis or exposure to hepatitis

How to prepare

You may need to stop taking certain medicines before the test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

An AST test is usually ordered with other blood tests. You usually need to fast (not eat or drink) for up to 12 hours before these tests. Your provider will let you know if there are any special instructions.

Sample type

Blood

Other names for this test

SGOT test, serum glutamic oxaloacetic transaminase test; aspartate transaminase test