Vitamin B12

Description: 
The Architect B12 assay is a chemiluminescent microparticle intrinsic factor for the quantitative determination of vitamin B12 in human serum or plasma
Clinical details: 
Vitamin B12 (cobalamin), a member of the corrin family, is a cofactor for the conversion of methylmalonyl Coenzyme-A (CoA) to succinnyl CoA. In addition, vitamin B12 is a cofactor in the synthesis of methionine from homocysteine, is implicated in the formation of myelin, and, together with folate, is required for DNA synthesis. Impaired vitamin B12 status, which may lead to clinical deficiency, is common in mixed patient populations, especially in those older than 60 years. Vitamin B12 deficiency can occur in patients with autoimmune disease (pernicious anaemia), severe primary hypothyroidism, those with ileal disease, patients on chronic therapy with antacids, proton pump inhibitor or H2 antagonists, or colchicine, and in chronic malnutrition states including alcoholism. Common causes also include adherence to vegetarian and vegan diets. A serum B12 test measures all cobalamins – holoTC (20-30%) and B12-haptocorrins (70-80%). Values below the normal expected range (except for pregnancy and congenital haptocorrin deficiency) may indicate that tissue B12 stores are becoming depleted. However, a B12 level in the low-normal range does not ensure that vitamin B12 levels are sufficient and patients may require further evaluation with other tests e.g. Active B12 (holoTC), homocysteine and methylmalonic acid.
Reference range: 

187-883

Synonyms or keywords: 
total B12, cobalamin/vitamin B12 deficiency, pernicious anaemia, haptocorrin deficiency
Units: 
ng/L
Sample type and Volume required: 
SST
Call in advance: 
No
Turnaround time: 
Samples processed daily between Mon-Friday (9am-5pm).
Storage and transport: 
separated serum can be sent by first class post
Contacts:
Nutristasis Unit at St Thomas'
0207188 6815 / 89543
St Thomas' Hospital
North Wing - 4th Floor
Westminster Bridge Road
London SE1 7EH

Laboratory opening times
Monday - Friday 09.00 - 17.00
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

Print as a PDF

Last updated: 17/08/2018