Methylmalonic Acid (MMA), Serum or Plasma

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Turnaround Time: 3 - 6 days
CPT Code:


Test Type: 2 mL Serum or plasma
Stability Time:



Room temperature

14 days


14 days


19 days

Freeze/thaw cycles

Stable x3

Reference Range:

0-378 nmol/L


Serum methylmalonic acid (MMA) measurement is used to evaluate individuals with signs and symptoms associated with vitamin B12 deficiency1-7 or congenital methylmalonic academia.8,9

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

MMA is a four-carbon molecule that is a product of the metabolic break-down of valine, isoleucine, and propionic acid.1 Vitamin B12 is a critical cofactor for the conversion of MMA to succinate.1 As a result, vitamin B12 deficiency causes an accumulation of MMA in the serum.1 MMA concentrations will often become elevated in the early stages of vitamin B12 while serum vitamin B12 levels are in normal range.1-4 Consequently, MMA measurement is used as a diagnostic test for vitamin B12 deficiency in persons with a low or low normal serum vitamin B12 concentration.5,6 Follow-up measurement of MMA can also be of value in assessing the effectiveness of vitamin B12 supplementation of deficient patients.7

Vitamin B12 deficiency causes macrocytic anemias and decreased erythrocyte survival due to abnormal maturation of erythrocyte precursors in the bone marrow.10,11 Pernicious anemia is a form of vitamin B12 deficiency that is caused by a lack of intrinsic factor.10,11 Low vitamin B12 intake, gastrectomy, malabsorption, and transcobalamin deficiency can also cause vitamin B12 deficiency.10,11 Although severe vitamin B12 deficiency is associated with anemia, hematologic signs are not always observed in patients with biochemically confirmed deficiency.12 Elderly patients with cobalamin deficiency may present with peripheral neuropathy, ataxia, memory impairment, depression, and dementia in the absence of anemia.13,14

A generally agreed on cutoff for elevated plasma MMA is 370 nmol/L.6,12 Approximately 2% of the US population and 7% of elderly persons have MMA concentrations above this threshold.12

1. Klee GG. Cobalamin and folate evaluation: Measurement of methylmalonic acid and homocysteine vs vitamin B12 and folate. Clin Chem. 2000 Aug; 46(8 Pt 2):1277-1283. PubMed 10926922

2. Clarke R, Refsum H, Birks J, et al. Screening for vitamin B-12 and folate deficiency in older persons. Am J Clin Nutr. 2003 May; 77(5):1241-1247. PubMed 12716678

3. Savage DG, Lindenbaum J, Stabler SP, Allen RH. Sensitivity of serum methylmalonic acid and total homocysteine determinations for diagnosing cobalamin and folate deficiencies. Am J Med. 1994 Mar; 96(3):239-246. PubMed 8154512

4. Langan RC, Zawistoski KJ. Update on vitamin B12 deficiency. Am Fam Physician. 2011 Jun 15; 83(12):1425-1430. PubMed 21671542

5. Carmel R. Biomarkers of cobalamin (vitamin B-12) status in the epidemiologic setting: a critical overview of context, applications, and performance characteristics of cobalamin, methylmalonic acid, and holotranscobalamin II. Am J Clin Nutr. 2011 Jul; 94(1):348S-358S. PubMed 21593511

6. Hølleland G, Schneede J, Ueland PM, Lund PK, Refsum H, Sandberg S. Cobalamin deficiency in general practice. Assessment of the diagnostic utility and cost-benefit analysis of methylmalonic acid determination in relation to current diagnostic strategies. Clin Chem. 1999 Feb; 45(2):189-198. PubMed 9931040

7. Hoey PL, Strain JJ, McNulty H. Studies of biomarker responses to intervention with vitamin B-12: A systematic review of randomized controlled trials. Am J Clin Nutr. 2009 Jun; 89(6):1981S-1996S. PubMed 19403638

8. Tanpaiboon P. Methylmalonic acidemia (MMA). Mol Genet Metab. 2005 May; 85(1):2-6. PubMed 15959932 9. Fowler B, Leonard JV, Baumgartner MR. Causes of and diagnostic approach to methylmalonic acidurias. J Inherit Metab Dis. 2008 Jun; 31(3):350-360. PubMed 18563633

10. Hvas AM, Nexo E. Diagnosis and treatment of vitamin B12 deficiency- An update. Haematologica. 2006 Nov; 91(11):1506-1512. PubMed 17043022

11. Ryan-Harshman M, Aldoori W. Vitamin B12 and health. Can Fam Physician. 2008 Apr; 54(4):536-541. PubMed 18411381

12. Pfeiffer CM, Caudill SP, Gunter EW, Osterloh J, Sampson EJ. Biochemical indicators of B vitamin status in the US population after folic acid fortification: Results from the National Health and Nutrition Examination Survey 1999-2000. Am J Clin Nutr. 2005 Aug; 82920:442-450. PubMed 16087991

13. Selhub J, Morris MS, Jacques PF, Rosenberg IH. Folate-vitamin B-12 interaction in relation to cognitive impairment, anemia, and biochemical indicators of vitamin B-12 deficiency. Am J Clin Nutr. 2009 Feb; 89(2):702S-706S. PubMed 19141696

14. Tangney CC, Tang Y, Evans DA, Morris MC. Biochemical indicators of vitamin B12 and folate insufficiency and cognitive decline. Neurology. 2009 Jan 27; 72(4):361-367. PubMed 19171834

Vogiatzoglou A, Oulhaj A, Smith AD, et al. Determinants of plasma methylmalonic acid in a large population: implications for assessment of vitamin B12 status. Clin Chem. 2009 Dec; 55(12):2198-2206. PubMed 19833840

Collection Details:

Collection Instructions:

Red-top tube, gel-barrier tube, or green-top (heparin) tube.

Separate serum or plasma from cells within one hour of collection.