What is this test?
This laboratory marker is measured as part of an assessment of metabolism and general health. It is not a diagnosis by itself.
Why might it be ordered?
- To investigate findings related to vitamin and amino-acid metabolism.
- For monitoring when requested because of symptoms or earlier results.
- As one part of a set of findings rather than the only test for disease.
What sample is needed?
A blood specimen is usually used, but the catalogue does not specify the exact material or method. Confirm the requirements with the laboratory.
How should you prepare?
Food, supplements, and medicines may matter depending on the marker and method. Do not change them on your own; obtain test-specific instructions.
How should you understand the result?
The reported value is compared with the interval for the method used. A clinician interprets it with other findings and the reason for testing.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.