86010:METHYLMALONIC ACID (MMA), QUANTITATIVE, SERUM
Author PeaceHealth Laboratories
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| Methodology: |
Tandem Mass Spectrometry (MS/MS) |
| Edit Date: |
2/8/2010 |
| Performed: |
Daily |
| Released: |
48 hours after setup at PeaceHealth Laboratories’ reference lab. |
| CPT Code: |
83921-90 |
| Specimen Collection Details |
| Collection: |
One 7.5 mL serum separator tube (SST). Also acceptable: One 4 mL lavender top tube (EDTA), 4 mL green top tube (sodium heparin), 4.5 light blue top tube (sodium citrate), or 4 mL grey top tube (sodium fluoride/potassium oxalate). |
| Handling: |
Allow to clot, centrifuge and separate serum or plasma from cells into a plastic vial. Freeze. Keep cold if there is more than one freeze/thaw cycle. If multiple tests are ordered, send separate specimen for this test. |
| Stability: |
18 hours ambient, 4 days refrigerated, or 1 month frozen. NOTE: Ambient stability cited from Hitchcox, K. et al. Stability of Biochemical Analytes in Blood Specimens Subjected to Delayed Processing. The FASEB Journal 2008 22:1102,3. |
| Standard Volume: |
3 mL serum or plasma. |
| Minimum Volume: |
1.5 mL serum or plasma. |
| Transport: |
Frozen on dry ice. |
| Comments: |
Serum methylmalonic acid is elevated in most patients with cobalamin deficiency. Methylmalonic acid and homocysteine are substrates for the two cobalamin-dependent enzymes, methyl-malonyl-CoA mutase and N5-methyltetrahydro-folate: homocysteine transferase. Methylmalonate accumulates in man when a cobalamin deficiency state exists which is identified by low normal concentrations of vitamin B12. Quantitation of serum methylmalonate provides a functional test for adequacy of vitamin B12. In a patient with low normal vitamin B12 levels that are due to vitamin B12 deficiency, serum methylmalonate is usually >0.4 µmol/L in the fasting state. |
| Rejection Criteria: |
Thawed or ambient specimen; gross hemolysis or lipemia. |