Methylmalonic Acid (MMA)
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Vitamin B12 is only synthesized by microorganisms in nature and thus, is obtained by human beings through their dietraff. Since the most important source of vitamin B12 is animal proteins, vegetarians may lack sufficient quantities of this vitamin in their diets.
Vitamin B12 deficiency is one of the most frequent vitamin deficiencies worldwide. So, this deficiency is an extremely important public health issue owing to its serious complications if it is not detected and treated appropriately. It is now considered to be a problem of global dimensions, frequently caused by dietary inadequacy, particularly among children and in women of reproductive age.
Numerous studies have now established that serum vitamin B12 has limited diagnostic value as a stand-alone marker. Low serum levels of vitamin B12 not always represent deficiency, and likewise, severe functional deficiency of the micronutrient has been documented in the presence of normal and even high levels of serum vitamin B12 [2].
Methylmalonic acid thus considered to be a more specific marker of vitamin B12 deficiency. Serum values of MMA, ranging from >0.26 to 0.35 μmol/L indicate elevation of this metabolite.