Formula C4H6O4 IUPAC ID methylmalonic acid | Molar mass 118.091 g/mol | |
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What is methylmalonic acid and how does it relate to vitamin b12
Methylmalonic acid (MMA) (conjugate base methylmalonate) is a dicarboxylic acid that is a C-methylated derivative of malonate.
Contents
- What is methylmalonic acid and how does it relate to vitamin b12
- Methylmalonic acidemia
- Pathology
- References
The coenzyme A linked form of methylmalonic acid, methylmalonyl-CoA, is converted into succinyl-CoA by methylmalonyl-CoA mutase, in a reaction that requires vitamin B12 as a cofactor. In this way, it enters the Krebs cycle, and is thus part of one of the anaplerotic reactions.
Methylmalonic acidemia
Pathology
Increased methylmalonic acid levels may indicate a vitamin B12 deficiency. However, it is sensitive (those with the disease almost always test positive) but not specific (those that do not have the disease do not always test negative). MMA is elevated in 90-98% of patients with B12 deficiency. It has lower specificity as 20-25% of patients over the age of 70 have elevated levels of MMA, but 25-33% of them do not have B12 deficiency. For this reason, MMA test is not routinely recommended in the elderly.
An excess is associated with methylmalonic acidemia.
MMA concentrations in blood are measured by Gas chromatographic Mass spectrometry or LC-MS and the expected values of MMA in healthy people are between 73-271 nmol/L.