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|Test Update Information|
|Clinical Questions||Does my patient have anemia due to a nutritional deficiency?|
|Performed by||China Basin Chemistry|
|In House Availability||Wednesday, Sunday (day shift)|
|Method||Competitive immunoassay using direct chemiluminescent technology (Siemens Centaur)|
|Collection Instructions||Avoid hemolysis.|
|Container type||Gold top or Red top|
|Amount to Collect||1 mL blood|
|Preferred volume||0.5 mL serum|
|Min. Volume||0.25 mL serum|
|UCSF Rejection Criteria||Hemolyzed|
|Processing notes||Freeze serum at -20C within 24 hours of draw.|
Reference range adopted from vendor performed studies and verified by running blood donor samples (excluding autologous donors) collected at the UCSF Blood Donor Center.
|Stability||Room temperature 8 hours, refrigerated 2 days.|
|Turn around times||1-5 days|
|Additional information||To convert ng/L to pmol/L (SI units) multiply by 0.738.
Cobalamin in the plasma and cytosol is bound to several proteins, including intrinsic factor, transcobalamins I and II and haptocorrin. Biologically active cobalamin is carried by intrinsic factor in the gut and by transcobalamin II in plasma. Changes in the other binding proteins ("R proteins"), can alter total cobalamin without affecting normal biological activity. Similarly, some patients may be deficient in biologically active forms of cobalamin despite "normal" or borderline low total cobalamin. If the measured cobalamin level is inconsistent with the clinical presentation, additional testing for increased serum levels of methylmalonic acid may be helpful in confirming or rejecting a diagnosis of B12-deficiency in individuals with normal or borderline low levels of cobalamin.
|Last Updated||7/8/2013 11:00:30 AM|
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