Methylmalonic acid: Difference between revisions
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==Pathology== |
==Pathology== |
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Increased methylmalonic acid levels may indicate a vitamin [[Vitamin B12 deficiency|B<sub>12</sub> deficiency]]. However, it is sensitive (those with the disease almost always test positive) but not specific (those that do not have the |
Increased methylmalonic acid levels may indicate a vitamin [[Vitamin B12 deficiency|B<sub>12</sub> deficiency]]. However, it is sensitive (those with the disease almost always test positive) but not specific (those that do not have the vitamin B12 deficiency may have elevated levels of methylmalonic acid, thus do not always test negative).<ref>{{cite web|url=https://www.med.emory.edu/EMAC/curriculum/diagnosis/sensand.htm|title=Sensitivity and Specificity|website=www.med.emory.edu}}</ref> MMA is elevated in 90–98% of patients with B<sub>12</sub> 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 B<sub>12</sub> deficiency. For this reason, MMA test is not routinely recommended in the elderly.<ref>{{cite web|url=http://www.dizziness-and-balance.com/disorders/central/b12.html|title=B12 Deficiiency and Dizziness|website=www.dizziness-and-balance.com}}</ref> |
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An excess is associated with [[methylmalonic acidemia]]. |
An excess is associated with [[methylmalonic acidemia]]. |
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Revision as of 16:43, 6 January 2020
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| Names | |
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| IUPAC name
2-Methylpropanedioic acid
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| Other names
Methylmalonic acid
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.007.473 |
| EC Number |
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| KEGG | |
| MeSH | Methylmalonic+acid |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C4H6O4 | |
| 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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Methylmalonic acid (MMA) (conjugate base methylmalonate) is a dicarboxylic acid that is a C-methylated derivative of malonate.
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.
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 vitamin B12 deficiency may have elevated levels of methylmalonic acid, thus do not always test negative).[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]
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.[4][5]
See also
References
- ^ a b "Dissociation Constants Of Organic Acids And Bases". zirchrom.com.
- ^ "Sensitivity and Specificity". www.med.emory.edu.
- ^ "B12 Deficiiency and Dizziness". www.dizziness-and-balance.com.
- ^ Isber, Sonia (2007). "The role of poor nutritional status and hyperhomocysteinemia in complicated pregnancy in Syria" (PDF). doi:10.22028/D291-20838.
{{cite journal}}: Cite journal requires|journal=(help) - ^ "Methylmalonic Acid, Serum or Plasma (Vitamin B12 Status)". ltd.aruplab.com.