Vitamin B12; Cobalamin Deficiency
Serum or Plasma
Quest forwards to LabCorp (TSO)
Other Reference Test
Monday, Wednesday, Friday
2-4 mL Blood
Red Top (No Additive)
Plasma collected in a heparin (green-top) tube is also acceptable.
Room Temp: 14 Days; Refrigerated: 14 Days; Frozen: 14 Days
2 mL Serum or Plasma
1 mL Serum or Plasma
Centrifuge and separate within one hour of collection. TSO required.
Cystathionine, Homocysteine, 2-Methylcitric acid and Methylmalonic acid
Useful for diagnosing and distinguishing between B12 and folate deficiency. Elevated levels of methylmalonic acid provide an early indication of cobalamin (B12) deficiency. LabCorp test code: 706960. Requires TSO form.