Methylmalonic acid

Methylmalonic acid (MMA) (conjugate base methylmalonate) is a dicarboxylic acid that is a C-methylated derivative of malonate.

Methylmalonic acid
Methylmalonic acid.svg
IUPAC name
2-Methylpropanedioic acid
Other names
Methylmalonic acid
3D model (JSmol)
ECHA InfoCard 100.007.473
EC Number
  • 208-219-5
MeSH Methylmalonic+acid
Molar mass 118.088 g/mol
Density 1.455 g/cm−3
Melting point 134 °C (273 °F; 407 K)
Acidity (pKa) pKa1 = 3,07[1]
pKa2 = 5,76[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox 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.


Increased methylmalonic acid levels may indicate a vitamin B12 deficiency. However, it is sensitive (those with the deficiency almost always test positive) but not specific (those that do not have vitamin B12 deficiency may have elevated levels of methylmalonic acid detected).[2] 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.[3] Moreover, recently MMA accumulation in the blood with age had been linked with the tumours.[4]

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.[5][6]

See alsoEdit


  1. ^ a b "Dissociation Constants Of Organic Acids And Bases".
  2. ^ "Sensitivity and Specificity".
  3. ^ "B12 Deficiency and Dizziness".
  4. ^ Gomes, Ana P.; Ilter, Didem; Low, Vivien; Endress, Jennifer E.; Fernández-García, Juan; Rosenzweig, Adam; Schild, Tanya; Broekaert, Dorien; Ahmed, Adnan; Planque, Melanie; Elia, Ilaria (2020-09-10). "Age-induced accumulation of methylmalonic acid promotes tumour progression". Nature. 585 (7824): 283–287. doi:10.1038/s41586-020-2630-0. ISSN 0028-0836.
  5. ^ Isber, Sonia (2007). "The role of poor nutritional status and hyperhomocysteinemia in complicated pregnancy in Syria" (PDF). doi:10.22028/D291-20838. Cite journal requires |journal= (help)
  6. ^ "Methylmalonic Acid, Serum or Plasma (Vitamin B12 Status)".

Further readingEdit