Health question
What does a high ALT level mean?
Checked against the sources below on October 19, 2026
The short answer
ALT (alanine aminotransferase) is an enzyme found mostly in the liver. A higher-than-normal result can mean liver cells are irritated or injured, but mild rises are common and often temporary. One result on its own does not give a diagnosis; your clinician reads it alongside your other liver tests, medicines and history.
What ALT measures
- When liver cells are stressed, ALT leaks into the blood. That is why it is part of a standard liver panel, along with AST, ALP, GGT and bilirubin.
- Normal ranges differ between laboratories. Always compare your result with the range printed on your own report.
Common reasons ALT can be raised
- Fat in the liver linked to weight, diabetes or high cholesterol (metabolic dysfunction-associated steatotic liver disease).
- Alcohol, some medicines and supplements (for example high-dose acetaminophen, some statins, and certain herbal products).
- Viral hepatitis and other liver conditions.
- Short-term causes such as hard exercise in the days before the test.
Questions to ask your doctor
- How high is my result compared with the range, and has it changed since my last test?
- Could any of my medicines or supplements be playing a part?
- Do I need a repeat test or other tests? Very high results, or yellow skin or eyes, dark urine or belly pain, need prompt medical attention.
Check your own medicines and results
MidLune checks your medicines and supplements against each other, reads your lab reports in plain words, and helps you prepare questions for your next visit.
Create your accountSources
- MedlinePlus: ALT blood test (opens in a new tab)
- Cleveland Clinic: Alanine transaminase (ALT) (opens in a new tab)
- NHS: Liver function tests (opens in a new tab)
This page is general information, not medical advice. It does not replace a conversation with your doctor or pharmacist. See our medical disclaimer.