ALT blood test
Alanine aminotransferase
In short
A typical adult ALT result is 7 to 45 U/L for women and 7 to 55 U/L for men. A small rise is common and often settles on its own. The size of the rise, whether it lasts, and the other liver tests matter more than one number. Always read your result against the range printed on your own report.
An enzyme that lives mostly inside liver cells.
When liver cells are irritated or hurt, ALT leaks into the blood and the level goes up. Because most ALT comes from the liver, doctors use it as a first check on liver health. A mild rise is one of the most common reasons a routine test comes back flagged.
Is my ALT high or low?
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Typical range
| For | Range | Unit |
|---|---|---|
| Female | 7–45 | U/L |
| Male | 7–55 | U/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your ALT is high
A small rise is common and often settles on its own. The size of the rise, whether it lasts, and the other liver tests matter more than one number.
Common reasons
- Extra fat stored in the liver, often with weight gain or high blood sugar
- Alcohol in the days before the test
- Hard exercise, especially weight training, in the days before
- Some medicines and supplements, such as some pain relievers or cholesterol medicines
- A recent viral infection, such as mono (mononucleosis)
- Less often: liver inflammation (hepatitis) from a virus or the immune system
- Less often: other liver conditions, such as iron overload or liver scarring (cirrhosis)
If your ALT is low
A low ALT is rarely a concern, and doctors usually don't act on it.
Common reasons
- Normal variation between people
- Low vitamin B6, which ALT needs to work
- Long-term kidney disease or dialysis
What can throw it off
Hard exercise, alcohol and some supplements in the days before the test can raise ALT for a while.
Questions to take to your appointment
- 1Is this rise small enough to just repeat the test?
- 2Could my medicines, supplements or recent exercise explain it?
- 3Do my other liver results point the same way?
Read together with
Doctors rarely read ALT alone. These usually sit next to it.
Quick answers
What is the ALT blood test?
ALT (Alanine aminotransferase): An enzyme that lives mostly inside liver cells. When liver cells are irritated or hurt, ALT leaks into the blood and the level goes up. Because most ALT comes from the liver, doctors use it as a first check on liver health. A mild rise is one of the most common reasons a routine test comes back flagged.
What is a normal ALT level?
For most adults, ALT is typically 7 to 45 U/L for women and 7 to 55 U/L for men. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high ALT mean?
A small rise is common and often settles on its own. The size of the rise, whether it lasts, and the other liver tests matter more than one number. Common reasons include extra fat stored in the liver, often with weight gain or high blood sugar; alcohol in the days before the test; hard exercise, especially weight training, in the days before; and some medicines and supplements, such as some pain relievers or cholesterol medicines. A doctor reads it together with your other results and how you feel.
What does a low ALT mean?
A low ALT is rarely a concern, and doctors usually don't act on it. Common reasons include normal variation between people; low vitamin B6, which ALT needs to work; and long-term kidney disease or dialysis.
What can affect my ALT result?
Hard exercise, alcohol and some supplements in the days before the test can raise ALT for a while.
What should I ask my doctor about my ALT?
Questions worth taking to the appointment: Is this rise small enough to just repeat the test? Could my medicines, supplements or recent exercise explain it? Do my other liver results point the same way?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
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