What it measures
Methylmalonic acid is a substance handled in a step of the body's chemistry that needs vitamin B12. When cells are short of B12 the step slows and MMA builds up in the blood, so it shows B12 shortage at the level of the cells.
Why people test it
- Measured when a B12 result is borderline, to see whether cells are actually short of B12.
- Checked when symptoms such as tingling or tiredness suggest low B12 despite a normal B12 result.
- Looked at by people more likely to run low on B12, such as vegans or people taking metformin.
Typical range
Ranges vary by lab, method, age and sex, and your report shows the lab's own range. Reduced kidney function also raises MMA.
Finger-prick or vein?
Taken from a vein. Providers offer it only as a vein draw, at a clinic or with a visiting nurse.