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HelpTest Code B12 Vitamin B12, Plasma
Specimen Type
Preferred: Plasma
Acceptable: Serum
Container
Plasma: Li-Heparin (Mint Green or Dark Green)
Serum: Red Top tube or Gold STT
Preferred Volume
3 mL
Offsite Collection Instructions
1. Fasting (8-14 hours) specimens are recommended.
2. Serum gel tube should be centrifuged within 2 hours of collection.
3. Red-Top tube or Dark Green Li-Heparin tube should be centrifuged and aliquot within 2 hours of collection.
UCMC Collection Instructions
1. Fasting (8-14 hrs) specimens are recommended. Protect sample from light.
2. Samples should be spun within 2 hours of collection.
Availability
24/7
Turnaround Time
4 hrs
STAT Availability
Not Available
Test Usage
Useful as an aid in the investigation of macrocytic anemia and workup of deficiencies seen in megaloblastic anemias.
Test Methodology
Electrochemiluminescence Immunoassay (ECLIA)
Additional Information
A normal serum concentration of vitamin B12 does not rule out tissue deficiency of vitamin B12. The most sensitive test for vitamin B12 deficiency at the cellular level is the assay for MMA. If clinical symptoms suggest deficiency, measurement of MMA and homocysteine should be considered, even if serum vitamin B12 concentrations are normal.
CPT Code
82607
Test Includes
Quantitative determination of vitamin B12 in plasma or serum
Critical Results
None
Test Limitations
In patients receiving therapy with high biotin doses (i.e. >
5 mg/day), no sample should be taken until at least 8 hours after
the last biotin administration.
Patients taking vitamin B12 supplementation may have misleading
results.
Reference Range
240-900 pg/mL
Minimum Volume
0.5 mL
Fee Code
69271