A patient seated in the chair before a blood draw
In person

ALT

A liver enzyme that reflects stress on liver cells, from one draw.

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  • 2,000+ lab locations. Find one near you
  • Nothing due at the lab. FSA / HSA accepted
  • Ordered by a licensed clinician

At a glance

Collection
Blood draw
A standard blood draw at the lab.
Preparation
None
Nothing to do ahead of time. Water is fine.
Results
1 to 2 days
Typical turnaround after your visit.
Where
2,000+ lab locations
Nationwide, with nothing due at the lab.

About this test

ALT (alanine aminotransferase) is an enzyme found mainly in liver cells. When those cells are irritated or damaged, more ALT can leak into the blood. ALT is more specific to the liver than AST, so the two are often read together. It reflects stress on the liver, not how well it works.

For adults 18 and older. Test availability varies by lab location.

Who should take this test?

This test is for adults checking in on liver health, following up on a past ALT result, or tracking the liver while taking a medicine, with a healthcare provider’s input.

Ask about this test

Not sure this is the right test?

AI-generated. For information only, not medical advice. Call 911 for an emergency.

What does this test measure?

Your result shows how much ALT is in your blood, which can help you and a healthcare provider see whether your liver may be under stress and whether to look further.

Alanine aminotransferase (ALT)
ALT is an enzyme found mostly in your liver. When liver cells are inflamed or injured, more ALT moves into the blood, so it is one of the more liver-specific enzymes. Alcohol, some medicines, and fat in the liver can raise it, and a provider reads it with AST and other results.
Why it’s measured: One of the more liver-specific enzymes on a routine panel, read alongside AST.

How it works

  1. Step 1

    Order online

    Check out here. A licensed clinician in your state reviews your order and sends it to the lab.

  2. Step 2

    Visit a lab

    Bring a photo ID to any of 2,000+ lab locations. No fasting needed, and nothing is due at the lab.

  3. Step 3

    Get your results

    Results post to your account, usually in 1 to 2 days, each number next to the lab’s reference range.

Find a lab near you

Choose from 2,000+ lab locations nationwide. Your order works at any of them.

What your results tell you

ALT is reported as enzyme activity in units per liter (U/L) and shown next to the lab’s reference range for comparison.

  • Your number next to the lab’s reference range
  • Explained in plain language
  • A licensed clinician reviews your order and, if appropriate, orders the test.
  • A lab report you can download and share

A raised ALT has many possible causes. A healthcare provider can explain your result and whether a repeat or follow-up test makes sense.

Clinical-grade testing, from the comfort of home.

From the lab to your report, every step of our process meets the gold standard in medical testing.

  • CLIA-certified labs

    Every lab we partner with is certified under the Clinical Laboratory Improvement Amendments, meeting both state and federal standards with regular independent inspections.

  • We protect your health data

    We protect your health data with encryption and do not sell it. Some results must be reported to public health authorities by law. See our Privacy Notice.

  • Rigorous quality assurance

    All partner labs run regular internal quality checks, participate in proficiency testing, and comply with federal and state lab regulations.

  • Clinician-reviewed reports

    Results are reviewed by an independent, licensed clinician.

Questions

Common questions.

Anything else, our care team answers by phone, text, or email.

Both are enzymes that can rise when liver cells are stressed. ALT is found mostly in the liver, while AST is also found in the heart, muscles, and other tissues.

That makes ALT the more liver-⁠specific of the two. Reading them together helps a healthcare provider judge whether a high AST is likely coming from the liver or from somewhere else.

Many things can stress liver cells, including some medicines, alcohol, extra fat stored in the liver, and infections such as viral hepatitis. A result above the lab’s reference range does not say which of these applies.

A healthcare provider looks at your history and other results and may suggest a repeat test. Don’t stop or change any medicine without talking with your healthcare provider.

Not on its own. ALT reflects stress on liver cells around the time of the draw. Liver enzymes are markers of liver injury, not direct measures of how well the liver works. A healthcare provider reads ALT with your history and other results to decide whether anything else is needed.

Sulfasalazine, a medicine for some bowel and joint conditions, can make ALT read falsely low. If you take it, tell the healthcare provider who reads your results. Don’t stop or change any medicine without talking with your healthcare provider.

Lab tests are informational and don’t diagnose conditions on their own. Available to adults 18 and older; test availability varies by lab location. A licensed clinician reviews your order and, if appropriate, orders the test. All testing is performed at CLIA-certified laboratories. Not for emergencies: if you think you may be having a medical emergency, call 911.