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Test Code LAB1883 Methylmalonic Acid, Quantitative, Urine

Additional Codes

MMAU

Useful For

Evaluating children with signs and symptoms of methylmalonic acidemia using urine specimens

 

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

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Urine


Specimen Required


Patient Preparation: Overnight fast required

Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube

Specimen Volume: 4 mL

Collection Instructions: Collect second-voided specimen after an overnight fast.


Specimen Minimum Volume

1.2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen (preferred) 28 days
  Refrigerated  28 days
  Ambient  21 days
Medical University of South Carolina Note:

On-campus collections: Tube to 99 or deliver to University Extension Hospital Room EH318 
 
Off-campus collections: 
Specimen to be stored/transported Frozen
 

Reference Values

<3.60 mmol/mol creatinine

Day(s) Performed

Monday through Friday

CPT Code Information

83921

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MMAU Methylmalonic Acid, QN, U 25116-5

 

Result ID Test Result Name Result LOINC Value
80290 Methylmalonic Acid, QN, U 25116-5

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 vitamin B12 (cobalamin) deficiency.

Method Description

Methylmalonic acid (MMA) is determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) stable isotope dilution analysis. The specimen is mixed with an internal standard (methyl-d3-malonic acid). MMA and d3-MMA are isolated by solid phase extraction. LC-MS/MS is performed using mobile phases and a short column to separate MMA and d3-MMA from the bulk of the specimen matrix. The MS/MS is operated in the multiple reaction monitoring (MRM) negative mode to follow the precursor to product species transitions. Separation of MMA/d3-MMA from the more physiologically abundant succinic acid is accomplished by the careful selection of MRM transitions and optimization of the LC separation. The ratios of the extracted peak areas of MMA to d3-MMA determined by LC-MS/MS are used to calculate the concentration of MMA present in the sample.(Unpublished Mayo method)

Report Available

3 to 5 days

Specimen Retention Time

1 week

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Method Name

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

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Biochemical Genetics Test Request (T798)

-Benign Hematology Test Request (T755)