Vitamin B12, Reflexive

Label Mnemonic:	B12R
Epic code:	LAB882
Downtime form:	Doctor/Provider Orders - Pathology Core and Specialty Care Nursery

Chemistry
6240 RCP
356-3527

Specimen(s):

Serum

Collection Medium:

Red top tube 5 mL (Clot Activator)

Alternate Collection Media:

Call laboratory for additional acceptable specimen collection containers.

Minimum:

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: 232 - 1245 pg/mL
Indeterminate: 150-231 pg/mL
Deficient: is less than 150 pg/mL

New analytical immunoassay for vitamin B12 with different reference range instituted on 12/19/2017.

Comments:

This assay may be significantly impacted by high-dose biotin (>5 mg dose) taken within previous 12 hours. High concentrations of biotin may lead to falsely increased results. These concentrations may be found in patients taking over-the-counter supplements with biotin content much higher than nutritional requirements for biotin. Specimens should not be collected until at least 12 hours after the last dose.

This test reflexes to methylmalonic acid if vitamin B12 < 300 pg/mL and additionally to intrinsic factor blocking antibody if vitamin B12 < 232 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).

No interference was observed from rheumatoid factors up to a 
concentration of 1500 U/mL.

In vitro tests were performed on 16 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.

This assay is designed to avoid interference due to anti-intrinsic 
factor antibodies. 

For diagnostic purposes, the vitamin B12 findings should always be 
assessed in conjunction with the patient's medical history, clinical 
examination and other findings.

Methodology:

Electrochemiluminescence immunoassay

CPT Code:

82607

See Additional Information:
Biotin Interference with Immunoassays
Specimens Requiring Immediate Delivery