Ordering Guidance

Ask patients if they have received a vitamin B12 injection or radiolabeled vitamin B12 injection within the last 2 weeks. Patient results will not reflect deficiency or malabsorption after recent B12 injection. If patient has received such an injection within the past 2 weeks, this test should not be ordered.

This test provides a measurement of serum vitamin B12 level only. For a more comprehensive workup, order ACASM / Pernicious Anemia Cascade, Serum, which initiates testing with measurement of vitamin B12. Depending on the vitamin B12 concentration, testing for intrinsic factor blocking antibody, gastrin, and methylmalonic acid may be added.

Necessary Information

Ask patients if they have received a vitamin B12 injection within the last 2 weeks. Patient results will not reflect deficiency or malabsorption after recent B12 injection. If patient has received an injection within the past 2 weeks, this test should not be ordered.

Specimen Required

Patient Preparation: This test should not be performed on patients who have received a vitamin B12 injection or radiolabeled vitamin B12 injection within the previous 2 weeks.

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.6 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.