AST (aspartate transaminase): reference ranges

In shortA common adult reference range is 8–33 U/L. AST rises with liver injury, but also with heart or muscle damage; low values are usually normal.

Reference ranges

Group	Reference range
Adults	8–33 U/L

Normal value ranges vary slightly among laboratories, and some labs use different measurements or test different samples. Use the reference range printed on your report.

Check your value

Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.

A rough comparison with a typical range, not a diagnosis. Reference ranges vary between laboratories — check the range on your own report and let a clinician interpret the result.

What this marker is

AST (aspartate aminotransferase) is an enzyme found in high levels in the liver, the heart, and the muscles, and in smaller amounts in other tissues. When cells that contain AST are injured, the enzyme is released into the blood, and the measured level climbs. The result is reported in units per liter (U/L).

Because AST lives in several organs, a raised value is less specific to the liver than ALT. That is why the test is mainly ordered alongside ALT, alkaline phosphatase, and bilirubin: the pattern across the group points much more precisely at the source than any single enzyme.

The test uses a standard blood sample from a vein and takes a few minutes. No special preparation is needed. As with other enzymes, it is worth telling the provider about the medicines you take and about recent intense exercise or medical procedures.

Low AST values are generally considered normal and rarely attract attention. The clinical weight sits on the high side: how high the value is, which other tests moved with it, and whether the rise is new or long-standing.

When it is high

Hepatitis and cirrhosisA swollen, inflamed, or scarred liver releases AST from injured cells, just as it releases ALT.

Heart attack and heart proceduresThe heart muscle is rich in AST, so a heart attack or a heart procedure can raise the level without any liver problem.

Muscle disease or traumaInjured skeletal muscle releases AST. Deep burns, seizures, and surgery can push the level up for the same reason.

Alcohol and liver-toxic medicinesDrugs that are toxic to the liver — above all alcohol and acetaminophen — injure liver cells and raise AST.

Mononucleosis, pancreatitis, hemochromatosisInfectious mononucleosis, an inflamed pancreas, and too much iron in the body are further reasons for a high AST.

Reduced blood flow or liver tumorsLiver ischemia, liver tissue death, and liver cancer or tumors also appear on the list of causes.

When it is low

Usually a normal findingLow levels of AST in the blood are usually considered normal and are not treated as a sign of disease.

What can skew the result

These factors can shift the value without any disease — worth considering before a retest:

Strenuous exercisePregnancyCertain medicinesAge and sex

How to prepare

No special preparation is needed. Tell your provider about the medicines you take; pregnancy, exercise, age, and sex can also influence the result.

When a retest makes sense

A high value is read together with ALT and the other liver tests. If muscle or heart damage is possible, the provider adds the tests that separate those sources before repeating AST.

Who usually reviews this result

A result outside the reference range is usually reviewed by: your GP or primary care doctor; a gastroenterologist or hepatologist if liver disease is suspected. Bring your lab report and any previous results to the appointment.

Names used on lab reports

Your report may use any of these names:
ASTAspartate aminotransferaseAspartate transaminaseSGOTSerum glutamic-oxaloacetic transaminase

Units

Measured in: U/L

Several markers on your report?

See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.

Get your results explained See an example

Frequently asked questions

Can AST be high without liver disease?

Yes. AST is also stored in the heart and skeletal muscles, so a heart attack, muscle trauma, deep burns, seizures, or recent surgery can raise it with a perfectly healthy liver. This is exactly why AST is read together with ALT.

Is low AST a problem?

Usually not. Low AST values are generally considered normal and do not, on their own, point to disease.

Do I need to fast for an AST test?

No special preparation is needed for AST itself. If your blood draw includes other tests that require fasting, your provider will tell you in advance.

Sources

AST Test: MedlinePlus Medical Test — MedlinePlus, National Library of Medicine. Accessed: August 29, 2026.
Aspartate aminotransferase (AST) blood test: MedlinePlus Medical Encyclopedia — MedlinePlus, National Library of Medicine. Accessed: August 29, 2026.

AST (aspartate transaminase)