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22882 Methylmalonic Acid, Urine (MMAU)

Methylmalonic Acid, Urine (MMAU)
Test Code: MISC
Synonyms/Keywords
B12 Deficiency, CblC, Cobalamin Deficiency, Methylmalonate, Methylmalonic Acid (MMA),
MMA (Methylmalonic Acid), Methylmalonic Aciduria
Useful For
Evaluating children with signs and symptoms of methylmalonic academia
           
Evaluating individuals with signs and symptoms associated with a variety of causes of cobalamin deficiency. 
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Urine​ ​Plastic 10 mL urine tube 4 mL​ ​1.2 mL
Collection Processing Instructions

​Collect second-voided specimen after an overnight fast.

Freeze specimen as soon as possible after collection in a plastic bottle.

Specimen Stability Information
Specimen Type Temperature Time
​Urine ​​ ​​
​Frozen (preferred) ​28 days
​Refrigerated ​28 days
​Ambient ​21 days
Interference

Diet, nutritional status, and age should be considered in the evaluation of serum or urine methylmalonic acid level.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Friday​ ​3-5 days
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)​
Reference Lab
Test 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, which includes serum and urine MMA levels.

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


Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories
<3.60 mmol/mol creatinine​
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
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​83921
Synonyms/Keywords
B12 Deficiency, CblC, Cobalamin Deficiency, Methylmalonate, Methylmalonic Acid (MMA),
MMA (Methylmalonic Acid), Methylmalonic Aciduria
Ordering Applications
Ordering Application Description
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Urine​ ​Plastic 10 mL urine tube 4 mL​ ​1.2 mL
Collection Processing

​Collect second-voided specimen after an overnight fast.

Freeze specimen as soon as possible after collection in a plastic bottle.

Specimen Stability Information
Specimen Type Temperature Time
​Urine ​​ ​​
​Frozen (preferred) ​28 days
​Refrigerated ​28 days
​Ambient ​21 days
Interference

Diet, nutritional status, and age should be considered in the evaluation of serum or urine methylmalonic acid level.

Useful For
Evaluating children with signs and symptoms of methylmalonic academia
           
Evaluating individuals with signs and symptoms associated with a variety of causes of cobalamin deficiency. 
Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories
<3.60 mmol/mol creatinine​
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
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Friday​ ​3-5 days
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)​
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​83921
For most current information refer to the Marshfield Laboratory online reference manual.