Methylmalonic acid - Serum
Vitamin B12 is needed to convert methylmalonic acid to coenzyme A. In vitamin B12 deficiency methylmalonic acid will accumulate in the body rather than being converted to coenzyme A. Both active vitamin B12 and serum B12 levels can be normal in people with the symptoms and biochemical signs of vitamin B12 deficiency, particularly when B12 levels are towards the lower end of the normal range. Measuring blood levels of methylmalonic acid can help to establish whether there is an underlying B12 deficiency.
What might a high result mean?
A high serum MMA result is usually suggestive of an underlying vitamin B12 deficiency.