Vitamin B12
Code:12008|CPT:82607|LOINC:2132-9
| Includes | Vitamin B12 |
|---|
Analysis details
Methodology
- Electrochemiluminescence immunoassay (ECLIA)
Expected Turnaround Time
1 day
Special Instructions
- Confirm whether the patient uses high-dose biotin; stop biotin supplements for at least 72 hours before collection.
- For infants younger than 1 year, withhold feeding for 30–40 minutes before the draw.
- Do not eat for 2–3 hours before specimen collection; water is allowed.
- Avoid physical exertion and emotional stress for 30 minutes before the blood draw.
- Do not smoke during the 30 minutes preceding collection.
How to use
The Vitamin B12 test (cobalamin assay) is used to identify vitamin B12 deficiency and to investigate macrocytosis (MCV >100 fL) and macrocytic/megaloblastic anemia, including pernicious anemia. It supports assessment of malabsorption and neurologic manifestations consistent with cobalamin deficiency, and is commonly ordered in the context of alcohol use disorder and during prenatal or preconception care. Reported elevations in serum vitamin B12 may accompany liver cell damage or myeloid leukemia and should be interpreted in clinical context. Because many immunoassays for cobalamin use biotin–streptavidin chemistry, high-dose biotin can artifactually increase measured concentrations. Pre-collection cessation of biotin for the specified interval helps reduce this source of analytical interference.
Limitations
Vitamin B12 deficiency is associated with macrocytosis and megaloblastic anemia and may present as pernicious anemia. Neurologic complaints and signs can be features of cobalamin deficiency, and malabsorption syndromes are common clinical settings prompting evaluation. Testing is also used in the nutritional assessment of individuals with alcohol use disorder and during prenatal or preconception care. Serum vitamin B12 can be increased in nondeficiency states, particularly with liver cell injury or myeloid leukemia. Analytical interference from high-dose biotin can produce spuriously elevated results in some electrochemiluminescence immunoassays; pausing biotin use for at least 72 hours prior to collection mitigates this effect.
| Unit | pg/mL | ||||
|---|---|---|---|---|---|
| Reference interval |
| ||||
| Indications | Clinical or laboratory suspicion of vitamin B12 deficiency, including pernicious anemia, Evaluation of macrocytosis (MCV >100 fL), Workup of macrocytic or megaloblastic anemia, Assessment in suspected or known malabsorption, Neurologic symptoms potentially attributable to cobalamin deficiency, Nutritional assessment in individuals with alcohol use disorder, Screening or evaluation in prenatal or preconception settings |
Possible Causes of Abnormal Results
Increased levels
- biotin (high dose)
Specimen Requirements
| Specimen | Serum |
|---|---|
| Container | Gold/Tiger Top (SST, Gel Separator) |
| Volume | 1 mL (min 0.7 mL) |
| Storage Instructions | Room temperature, Refrigerated, Frozen |
References
A. Sh. Byshevsky, O. A. Tersenov. Biochemistry for the Physician. Yekaterinburg, 1994.
A. Sh. Zaichik, L. P. Churilov. Fundamentals of Pathochemistry. St. Petersburg, 2001.
Shelke N, Keith L. Folic Acid Supplementation for Women of Childbearing Age versus Supplementation for the General Population: A Review of the Known Advantages and Risks. Int J Family Med. 2011.