Vitamin B12, Reflexive
Label Mnemonic: B12R
Epic Lab Code: LAB882
Downtime Form: A-1a General Laboratory Requisition
6240 RCP
Collection Medium:
Red top tube 5 mL (Clot Activator)
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
3 mL whole blood in red top tube or THREE Microtainer® devices.
Delivery Instructions:
Deliver to laboratory immediately after collection.
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
Normal: 211 - 946 pg/mL
Indeterminate: 150-210 pg/mL
Deficient: is less than 150 pg/mL

New analytical immunoassay for vitamin B12 with different reference range instituted on 11/26/2013.
This test reflexes to methylmalonic acid if vitamin B12 < 300 pg/mL and additionally to intrinsic factor blocking antibody if vitamin B12 < 211 pg/mL. These reflex tests carry additional charges if performed.

This test is also performed in the Iowa River Landing (IRL) clinical laboratory (for specimens drawn at that site).
Test Limitations:
The assay is unaffected by icterus (bilirubin is less than 65 mg/dL), hemolysis (Hb is less than 1.0 g/dL), lipemia (triglycerides is less than 1500 mg/dL) and biotin is less than 50 ng/mL. (criterion: recovery within plus or minus 10% of initial value). In patients receiving therapy with high biotin doses (i.e. is greater than 5 mg/day) no sample should be taken until at least 8 hours after the last biotin administration. No interference was observed from rheumatoid factors up to a concentration of 1500 U/mL. In vitro tests were performed on 54 commonly used pharmaceuticals. No interference with the assay was found. In rare cases interference due to extremely high titers of antibodies to streptavidin and ruthenium can occur. For diagnostic purposes, the vitamin B12 findings should always be assessed in conjunction with the patient's medical history, clinical examination and other findings.
Electrochemiluminescence immunoassay
CPT Code:
See Additional Information:
Specimens Requiring Immediate Delivery