Serum methylmalonic acid (MMA) measurement is used to evaluate individuals with signs and symptoms associated with vitamin B12 deficiency or congenital methylmalonic academia.
MMA is Vitamin B12 dependent byproduct of amino acid breakdown. Vitamin B12 deficiency causes an accumulation of MMA in the serum. MMA concentrations will often become elevated in the early stages of vitamin B12 deficiency even while serum levels of B12 appear normal. Consequently, It may be used as a diagnostic test for B12 deficiency in assessing the effectiveness of vitamin B12 supplementation of deficient patients.
Vitamin B12 deficiency causes macrocytic anemias and decreased erythrocyte survival due to abnormal maturation of erythrocyte precursors in the bone marrow. Pernicious anemia is a form of vitamin B12 deficiency that is caused by a lack of intrinsic factor.
Low vitamin B12 intake, gastrectomy, malabsorption, and transcobalamin deficiency can also cause vitamin B12 deficiency.
A generally agreed on cutoff for elevated plasma MMA is 370 nmol/L.