Methylmalonic Acid
A metabolic by-product that builds up when the body lacks functional vitamin B12.
| Typical reference range | below 318 nmol/L |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Vitamin B12 is required to convert methylmalonyl-CoA to succinyl-CoA. When B12 is insufficient at the tissue level, methylmalonic acid accumulates in blood and urine.
Why it matters
MMA is a sensitive and specific marker of functional B12 deficiency and can identify deficiency when serum B12 is borderline or normal.
What a high result can mean
High MMA indicates B12 deficiency at the tissue level. Kidney impairment, older age, dehydration and gut bacterial overgrowth can also raise it.
What a low result can mean
Low values are normal and not a concern.
What affects the result
Kidney function must be considered, since reduced clearance raises MMA. Levels fall within weeks of effective B12 treatment. Interpret with B12 and homocysteine.
Units and conversion
Usually reported in nmol/L.
- From umol/L: multiply by 1,000 to get nmol/L
Also called on lab reports
MMA, Methylmalonic Acid, Serum, Methylmalonic Acid, Serum or Plasma
Related tests: Vitamins & Nutrients
This page is educational and does not replace advice from a healthcare professional.