Sign in →

Test ID: MMAP Methylmalonic Acid (MMA), Quantitative, Plasma

Reporting Name

Methylmalonic Acid, QN, P

Useful For

Evaluating children with signs and symptoms of methylmalonic acidemia

 

Evaluating individuals with signs and symptoms associated with a variety of causes of cobalamin (vitamin B12) deficiency

Specimen Type

Plasma


Specimen Required


Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: EDTA

Specimen Volume: 1.5 mL


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Refrigerated (preferred) 48 days
  Ambient  48 days
  Frozen  48 days

Reference Values

≤0.40 nmol/mL

Day(s) and Time(s) Performed

Monday through Friday; Continuously until 12 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

83921

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MMAP Methylmalonic Acid, QN, P 13964-2

 

Result ID Test Result Name Result LOINC Value
31927 Methylmalonic Acid, QN, P 13964-2

Clinical Information

Elevated levels of methylmalonic acid (MMA) result from inherited defects of enzymes involved in MMA metabolism or inherited or acquired deficiencies of vitamin B12 or its downstream metabolites. Of the 2, nutritional deficiencies are much more common and can be due to intestinal malabsorption, impaired digestion, or poor diet. Elderly patients with cobalamin deficiency may present with peripheral neuropathy, ataxia, loss of position and vibration senses, memory impairment, depression, and dementia in the absence of anemia. Other conditions such as renal insufficiency, hypovolemia, and bacterial overgrowth of the small intestine also contribute to the possible causes of mild methylmalonic acidemia and aciduria.

 

MMA is also a specific diagnostic marker for the group of disorders collectively called methylmalonic acidemia, which include at least 7 different complementation groups. Two of them (mut0 and mut-) reflect deficiencies of the apoenzyme portion of the enzyme methylmalonyl-CoA mutase. Two other disorders (CblA and CblB) are associated with abnormalities of the adenosylcobalamin synthesis pathway. CblC, CblD, and CblF deficiencies lead to impaired synthesis of both adenosyl- and methylcobalamin.

 

Since the first reports of this disorder in 1967, many hundreds of cases have been diagnosed worldwide. Newborn screening identifies approximately 1 in 30,000 live births with a methylmalonic acidemia. The most frequent clinical manifestations are neonatal or infantile metabolic ketoacidosis, failure to thrive, and developmental delay. Excessive protein intake may cause life-threatening episodes of metabolic decompensation and remains a life-long risk unless treatment is closely monitored, including plasma and urine MMA levels.

 

Several studies have suggested that the determination of plasma or urinary methylmalonic acid could be a more reliable marker of cobalamin deficiency than direct cobalamin determination.

Interpretation

In pediatric patients, markedly elevated methylmalonic acid values indicate a probable diagnosis of methylmalonic acidemia. Additional confirmatory testing must be performed.

 

In adults, moderately elevated values indicate a likely cobalamin deficiency.

Clinical Reference

1. Fenton WA, Gravel RA, Rosenblatt DS: Chapter 94: Disorders of propionate and methylmalonate metabolism. In The Metabolic and Molecular Bases of Inherited Disease. In Scriver's The Online Metabolic and Molecular Basis of Inherited Disease (OMBBID). Edited by D Valle, A Beaudet, B Vogelstein, et al. McGraw-Hill. Accessed 08/17/2017

2. Klee GG: Cobalamin and folate evaluation measurement of methylmalonic acid and homocysteine vs vitamin B12 and folate. Clin Chem 2000:46(8):1277-1283

3. Hussein L, Abdel A, Tapouzada S, Boehles H: Serum vitamin B12 concentrations among mothers and newborns and follow-up study to assess implication on the growth velocity and the urinary methylmalonic acid excretion. Int J Vitam Nutr Res. 2009 Sep:79(5-6):297-307

Analytic Time

3 days (not reported on Saturday or Sunday)

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Forms

If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/benign-hematology-test-request-form.pdf)

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical