What is ALT?
ALT is an enzyme produced mainly in liver cells. Small amounts normally circulate in the blood, but when liver cells are damaged they release more ALT, raising the blood level.
ALT is considered one of the most specific markers of liver health. It is almost always measured alongside AST; comparing the two values helps narrow down the cause of any elevation.
Why might ALT be low?
ALT values below the reference range are generally not clinically significant. Low values can occasionally occur with severe vitamin B6 deficiency.
This information is educational. A single out-of-range result is rarely the whole picture — a healthcare professional can interpret your numbers alongside your overall health and history.
Context questions that matter
- →Was this result slightly or clearly outside the reference range?
- →Were related markers also high or low?
- →Is this new compared with previous tests?
- →Could recent illness, exercise, fasting, alcohol, supplements, or medication affect it?
- →Do you have symptoms that should be discussed with a clinician?
Markers often reviewed together with ALT
Clinicians rarely look at one number in isolation. These markers usually accompany ALT on a liver function panel and help put the result in context.
Lifestyle considerations
- •Limiting alcohol consumption supports healthy ALT levels
- •Maintaining a healthy weight reduces the risk of fatty liver-related ALT elevation
Questions to ask your doctor
- →Could any medication, supplement, alcohol intake, or recent intense exercise affect this low ALT result?
- →Should we compare this with ALT, AST, GGT, ALP and bilirubin together?
- →Is this a single abnormal value, or part of a broader liver-marker pattern?
Don't guess from one flagged result.
Start with the most relevant panel and see how your markers fit together in plain English.
Frequently asked questions
What does low ALT mean?
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ALT values below the reference range are generally not clinically significant. Low values can occasionally occur with severe vitamin B6 deficiency.
What is ALT?
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ALT is an enzyme produced mainly in liver cells. Small amounts normally circulate in the blood, but when liver cells are damaged they release more ALT, raising the blood level.
Can exercise, alcohol or medication affect ALT?
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They can sometimes affect liver-related markers. ALT is usually read with ALT, AST, GGT, ALP and bilirubin together with your recent context — recent intense exercise, alcohol intake, prescription medications and supplements all matter. One result alone cannot diagnose a condition.
Which liver markers should I compare with ALT?
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Common companions on a liver panel include ALT, AST, GGT, ALP, total bilirubin and direct bilirubin. The pattern across these markers is usually more informative than any single value — for example, GGT helps separate liver-side from bone-side raised ALP, and the AST:ALT ratio gives context for liver-enzyme elevation.
What supports healthy ALT levels?
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Limiting alcohol consumption supports healthy ALT levels. Maintaining a healthy weight reduces the risk of fatty liver-related ALT elevation