Vitamin B12

Test Code

B12

Alias/See Also

Epic: LAB67

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 3 mL

Minimum Volume

0.5 mL

Other Acceptable Specimens

Specimen Type: Plasma
Collection Container: Green top (Lithium heparin)

Instructions

Centrifuge and separate cells after clot formation and within 4 hours of collection

Transport Container

Plastic vial

Specimen Stability

Room temperature: 3 days
Refrigerated: 7 days
Frozen: 3 months

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unlabeled, mislabeled, wrong tube type, hemolyzed, QNS, exceeds specimen stability requirements.

Methodology

Chemiluminescent microparticle immunoassay (CMIA)

Setup Schedule

Daily

Report Available

Same day

Limitations

If the vitamin B12 results are inconsistent with clinical evidence, additional testing is suggested to confirm the result.
Heterophilic antibodies and RF in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassay. Patients routinely exposed to animals or to animal serum products can be prone to this interference and anomalous values may be observed.
Hemolysis has been demonstrated to exhibit negative interference in this B12 assay. Hemolyzed specimens should not be analyzed. Specimens containing above normal protein concentrations may generate repeated (2 or more) “3350 Unable to process test-aspiration error for (Sample Pipettor) at (RV 24)” errors. These specimens are unable to be tested using the ARCHITECT B12 assay.

Reference Range

211 - 911 pg/mL

Clinical Significance

Vitamin B12 is a member of the corrin family, and is a cofactor for the conversion of methylmalonyl Coenzyme-A to succinoyl CoA. In addition, B12 is a cofactor in the synthesis of methionine from homocysteine, is implicated in the formation of myelin, and, along with folate, is required for DNA synthesis. Vitamin B12 is absorbed from food after binding to a protein call intrinsic factor, which is produced by the stomach. Causes of B12 deficiency can be divided into three classes: nutritional deficiency, malabsorption syndromes, and other gastrointestinal causes. Vitamin B12 deficiency can cause megaloblastic anemia and can cause damage to the myelin sheath that surrounds and protects nerves, which may lead to peripheral neuropathy. People with intrinsic factor defects who do not get treatment eventually develop a megaloblastic anemia called pernicious anemia (PA). A serum B12 level below the normal expected range may indicate that tissue B12 levels are becoming depleted. Conditions associated with low serum B12 levels include iron deficiency, normal near-term pregnancy, vegetarianism, and partial gastrectomy/ileal damage, and Celiac disease, use of oral contraception, parasitic competition, pancreatic deficiency, treated epilepsy, and advancing age. Disorders associated with elevated levels of serum B12 include renal failure, liver disease, and myeloproliferative diseases.

Performing Laboratory
Inova Laboratories
2832 Juniper Street
Fairfax, VA 22031

Last Updated: March 6, 2023
Last Review: N. Wolford, March 6, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.