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Serum or plasma concentration of **aspartate aminotransferase (AST)**

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of an enzyme called aspartate aminotransferase (AST) in your blood. AST helps break down proteins and is found in both your liver and heart.

Quick summary

["AST helps doctors check for liver or heart damage."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
97535-9
Short code
Gas Pnl BldCV
Synonyms
Gas Pnl BldCV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What AST Measures

AST is an enzyme that plays a role in energy production in your cells. When your liver or heart is damaged, AST can leak into your bloodstream, raising its levels. This test helps identify conditions that may affect these organs.

Why It’s Done

Your doctor may order this test if you have symptoms like jaundice (yellow skin), fatigue, abdominal pain, or if you have a history of liver disease, heart problems, or recent injuries. It can also be part of routine check-ups or before certain treatments.

Common Conditions Linked to Elevated AST

High AST levels may suggest liver issues like hepatitis, fatty liver disease, or cirrhosis. It can also indicate heart problems, such as a heart attack, or other conditions like muscle damage or certain medications causing liver damage.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a liver function panel. Bring any medications you’re taking to your appointment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

AST levels alone don’t diagnose a condition, but they’re used alongside other tests and symptoms to guide further evaluation.

Short name

AST Level

Frequently asked questions

Will fasting affect my AST test?
Sometimes, fasting can influence liver enzyme tests, but AST specifically is less affected than other liver function tests like ALT. Your doctor will let you know if fasting is required for this test.
Can I take my usual medications before this test?
Yes, you can take your regular medications unless instructed otherwise. Some medications (like certain pain relievers or antibiotics) may affect liver enzymes, so always check with your doctor.
What does a normal AST level mean?
A normal AST level doesn’t mean there’s no liver or heart damage—it just means the enzyme is within a typical range. Doctors use AST along with other tests and symptoms to make a full assessment.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy