Vitamin B12 with Reflex to Methylmalonic Acid, Serum (Vitamin B12 Status)
Also known as: B12 MMA
Use
This test is the preferred reflex test for evaluating vitamin B12 deficiency in individuals with macrocytic or unexplained anemia or unexplained neurologic disease. When a Vitamin B12 level is less than 300 pg/mL, Methylmalonic Acid (MMA) measurement is automatically added to help confirm vitamin B12 deficiency. Elevated MMA levels can indicate vitamin B12 deficiency, renal insufficiency, or intravascular volume contraction.
Special Instructions
Protect specimens from light during collection, storage, and shipment. Serum should be centrifuged and separated from cells within 2 hours of collection, then transferred to a transport tube and refrigerated or frozen immediately.
Limitations
EDTA plasma and room temperature specimens are unacceptable. Grossly hemolyzed or lipemic specimens are also rejected. The test has specific stability requirements: the specimen is stable for 48 hours when refrigerated, and for 1 month when frozen. There may be factors such as renal insufficiency or volume contraction that affect methylmalonic acid levels, which should be considered when interpreting results.
New York Approved
Methodology
Immunoassay (CLIA)
Biomarkers
LOINC Codes
- 13964-2
- 2132-9
Result Turnaround Time
1-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1.0 mL
Minimum Volume
0.6 mL
Container
Plain red or serum separator tube
Collection Instructions
Protect from light during collection. Centrifuge and remove serum from cells within 2 hours. Transfer to ARUP standard transport tube and refrigerate or freeze immediately.
Storage Instructions
Refrigerate or freeze immediately after transfer to transport tube.
Causes for Rejection
EDTA plasma, room temperature specimens, grossly hemolyzed or lipemic specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Unacceptable |
| Refrigerated | 48 hours |
| Frozen | 1 month |