AST

What it is

AST (aspartate aminotransferase) is an enzyme found in the liver and also in muscle and other tissues.

Why it matters

Together with ALT, AST helps detect liver injury, though it is less liver-specific.

What high values can mean

A higher value can reflect liver injury, but also muscle strain or other tissue stress.

What low values can mean

A lower value is generally not a concern.

How to improve it

For liver-related rises, the same habits help as for ALT — weight, alcohol, activity and diet.

Food & lifestyle

Limiting alcohol and reducing fatty-liver risk factors supports a healthy AST; intense exercise can raise it temporarily.

Preparing for the test

Often part of a liver panel; fasting is not specifically required — follow your lab.

When to talk to a doctor

An abnormal AST is interpreted by a doctor with ALT to tell liver from muscle causes.

Related markers

• ALT
• GGT
• LDH

Sources

• MedlinePlus (NIH)
• Testing.com (AACC)

Content reviewed on June 26, 2026