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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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Item Value
Available Stat? No
Test code B12
Performed by? Chemistry
Sendout? no
Price range $$$
In House Availability Monday - Friday
Principle The Siemens Centaur method is a competitive binding assay using purified intrinsic factor and direct chemiluminescent technology.
Interpretation Decreased levels of serum Vitamin B12 are usually associated with true tissue Vitamin B12 deficiency. However, decreased serum Vitamin B12 levels also may be seen after acute blood loss, in iron deficiency anemia, in pregnancy, and in some patients with folic acid deficiency where there is no evidence of true tissue deficiency. Treatment of the primary disorder is often associated with a return of Vitamin B12 to normal levels. In occaÂsional instances, true tissue Vitamin. B12 deficiency causing neurologic deficits occurs with mildly decreased or even low normal serum B12 levels, with or without hematologic findings of B12 deficiency.

Elevated levels of serum Vitamin B12 are noted in myeloproliferative disorders, in the presence of increased levels of Vitamin B12binding protein (transcobalamines), and in acute hepatic disease.
Container type gold top gel tube
Amount to Collect 2 mL
Collection Instructions Plasma samples will not be assayed.
Sample type Blood
Normal range
Under age 65: 236 - 888 pg/mL (174 - 655 pmol/L)
Indeterminate: ≥ 160 and < 236 pg/mL (≥ 118 and < 147 pmol/L)
Deficient: < 160 pg/mL (< 118 pmol/L)
Over age 65: < 140 pg/mL (< 103 pmol/L) may indicate
B12 deficiency; but
low levels may occur
in the absence of anemia,
macrocytosis, or nervous disorders.
Stability 8 hours at room temp
2 days at 4°C
2 weeks at -20°C
Interferences 1. Auto- (rheumatoid factor) and heterophile antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this interference. Anomalous values, spuriously low or high, may be observed. Results inconsistent with clinical findings or previous laboratory values can be investigated by the laboratory for this phenomenon. Call the Clinical Chemistry Laboratory Medicine Resident (x65527, pager 415-443-2311).
References 1. Bayer, 111658 rev. K, 2003-04. Siemens Medical Solutions Diagnostics, Malvern, PA.
CPT coding 82607
Last Updated 10/23/2012 6:32:38 PM
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