ALT (Alanine Aminotransferase)
Also known as: ALT, SGPT, Alanine transaminase
ALT (alanine aminotransferase) is an enzyme found mainly in your liver. When liver cells are stressed or injured, more ALT can be released into the blood, which is why it is used to look at liver health.
Why it's measured
ALT is part of a liver panel and is usually interpreted alongside other liver enzymes and tests rather than on its own. Several everyday factors can nudge it up or down.
Typical range
Reference ranges vary by lab and may differ by sex. Because mild changes are common and have many causes, doctors read ALT together with the rest of the liver panel.
What high values can mean
A higher ALT is one signal doctors consider when evaluating the liver, alongside other enzymes, your history, and sometimes repeat testing. It is not a diagnosis by itself.
What low values can mean
Lower ALT values are generally not a concern on their own and are interpreted in context.
Questions to ask your doctor
- How does my ALT fit with the rest of my liver panel?
- Could anything I took or did recently have affected it?
- Should this be rechecked?
Want your full report explained?
Upload a lab PDF and Plain Lab walks you through every value in plain English.
Try the explainerEducational information only — not medical advice, diagnosis, or treatment. Reference ranges vary by lab; always use your own lab's range and discuss results with a qualified clinician.