48 hours after setup at PeaceHealth Laboratories’ reference lab.
Specimen Collection Details
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).
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.
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.
3 mL serum or plasma.
1.5 mL serum or plasma.
Frozen on dry ice.
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.
Thawed or ambient specimen; gross hemolysis or lipemia.