Methylmalonic Acid

Methylmalonic Acid (MMA) is an organic acid that accumulates when Vitamin B12 is deficient, as B12 is a necessary cofactor for the enzyme methylmalonyl-CoA mutase. Elevated serum or urine MMA is a sensitive and specific functional marker for Vitamin B12 deficiency, often rising before serum B12 levels fall below the reference range. MMA levels can also be increased by kidney disease (due to decreased excretion) and rare inherited metabolic disorders (methylmalonic acidemias).