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Liver panel · AST

What does AST mean on your blood test?

AST is an enzyme found in the liver as well as in muscle and other tissues. It is used alongside ALT to check liver health. Here is how to read your AST result, in plain language.

Typical range
8–48
U/L

What AST is

AST stands for aspartate aminotransferase, an enzyme that helps cells produce energy. Unlike ALT, which sits mostly in the liver, AST is also present in the heart, muscles, and other organs. When any of these tissues are injured, AST can rise in the blood, so the test is less specific to the liver on its own.

How to read your AST result

AST is reported in units per litre (U/L), and normal ranges vary between laboratories, so read your result against the range on your own report. A commonly cited range is around 8 to 48 U/L. Because AST comes from several tissues, a raised value is most useful when read together with ALT and the rest of the liver panel.

What a high AST can mean

A high AST can reflect liver-cell injury, but it can also follow strenuous exercise or muscle injury because of AST in muscle. The pattern between AST and ALT, and the ratio between them, helps a clinician judge whether the liver, muscle, or another tissue is the more likely source.

What usually happens next

See your own AST explained

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Common questions

Can exercise raise my AST?
Yes. Because AST is present in muscle as well as the liver, strenuous exercise or a muscle injury can temporarily raise it. This is one reason AST is interpreted alongside ALT, which is more specific to the liver, rather than on its own.
What is a normal AST level?
Normal AST ranges vary between laboratories, so compare your result to the reference range on your own report. A commonly cited range is around 8 to 48 U/L, and the specific method and your individual factors can shift it.
Why are ALT and AST always tested together?
Reading the two enzymes together, along with the ratio between them, gives more information than either alone. It helps a clinician judge whether a raised result is more likely coming from the liver or from another tissue such as muscle.

Related guides

ALT, explained
The more liver-specific enzyme
Understand your labs
Browse every marker, explained
C-reactive protein, explained
A marker of inflammation

Sources

  1. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); AST Test; [cited 2026 Jul 14]. Available from: https://medlineplus.gov/lab-tests/ast-test/
  2. MedlinePlus Medical Encyclopedia [Internet]. Bethesda (MD): National Library of Medicine (US); AST blood test; [cited 2026 Jul 14]. Available from: https://medlineplus.gov/ency/article/003472.htm
  3. MedlinePlus [Internet]. Bethesda (MD): National Library of Medicine (US); Liver Function Tests; [cited 2026 Jul 9]. Available from: https://medlineplus.gov/lab-tests/liver-function-tests/

Content last reviewed 9 July 2026. Reference ranges vary by laboratory; always read your results against the range printed on your own report.

This page explains a common lab marker in general terms using public information from the U.S. National Library of Medicine and other NIH sources. It is educational and is not a diagnosis or medical advice. Reference ranges differ between laboratories and the meaning of a result depends on your age, sex, medications, and overall health. Always discuss your own results with the clinician who ordered them.