What is this test?
ALT is an enzyme concentrated mainly in liver cells. A rise can signal liver-cell irritation or injury, although the number does not directly measure liver function.
Why might it be ordered?
- To screen for or investigate liver injury.
- To monitor a liver condition or medicine that may affect the liver.
What sample is needed?
A blood sample is required. The laboratory chooses the correct tube and handles the sample for this test.
How should you prepare?
Ask the laboratory whether you need to fast or attend at a particular time. Do not stop or change medicines or supplements unless your clinician tells you to.
How should you understand the result?
The degree and trend of elevation, other liver tests and clinical history help determine significance. A normal ALT does not exclude every liver condition.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.