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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Vitamin B12

Test Code(s): B12

CPT Code(s): 82607

Methodology: Chemiluminescent Immunoassay

Days Performed: Daily.

Turnaround Time: Stat: Not available stat.
Routine: 4 hours.


Specimen Requirements

Specimen: Blood

Collection Container: Preferred: Green cap with yellow ring (PST)
Also Acceptable: Green top, Red cap with yellow ring (SST), Red top

Collection Volume: Preferred: 1 mL
Pediatrics: 0.5 mL

Sample Analyzed: Serum or plasma

Volume Required: Preferred: 0.5 mL
Pediatrics: 0.2 mL

Specimen Processing: Centrifuge blood within 2 hours.  Transfer cell-free plasma/serum to plastic vial.  Refrigerate.  If transport time exceeds 48 hours, freeze plasma/serum sample.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.  Transport frozen specimen on dry ice.

Stability: Ambient: 2 hours on cells; 24 hrs off cells
Refrigerated: 48 hours
Frozen: 12 months


Interpretation

Reference Interval:

18 years and up: 193-986 pg/mL

Test Limitations:

Intrinsic Factor blocking antibodies are present in approximately half of pernicious anemia patients. There is a low frequency possibility that these antibodies may not be completely inactivated during the reaction pretreatment step. If test results are in conflict with the clinical diagnosis, consider testing for intrinsic factor blocking antibodies.

 

Patient samples may contain heterophilic antibodies that could react in immunoassays to give falsely elevated or depressed results.  A test result that is inconsistent with the clinical picture and patient history should be interpreted with caution.

 

Dextran 40 at 6 g/dL decreases Vitamin B12 results by 11.9% at 200 pg/mL.

 

B12, Vitamin
cobalamin
cyanocobalamin

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