ADVIA Centaur Active-B12 Assay
Vitamin B12 deficiency is an increasing global health concern. Although general prevalence is difficult to determine, the World Health Organization (WHO) estimates that clinical and subclinical B12 deficiency affects millions of individuals of all ages1. Estimation of prevalence is challenging due to differing opinions on criteria for deficiency, but may be as high as 10–15% in those over age 65, 31% in post-gastric surgery patients, 41% of long-term care residents, and 6–30% of patients taking metformin. Prevalence of subclinical deficiency may also be increasing in the general population due to increased use of proton-pump inhibitors.1-3
Common tests for vitamin B12 deficiency measure total vitamin B12, which is found in blood bound to two carrier proteins; approximately 70–90% is bound to haptocorrin and available only to specific cells in the small intestine; 10–30% is bound by transcobalamin. When B12 is bound to transcobalamin it is referred to as holotranscobalamin (holoTC). Only B12 in this form is available to other tissues for physiologic use1,4. Because this small fraction is the only form that is bioavailable it is also referred to as active-B12.
The ADVIA Centaur® Active-B12 (AB12) assay from Siemens Healthcare measures holoTC in the blood, resulting in improved accuracy, sensitivity, and specificity of B12 status. This makes active-B12 a useful marker of early vitamin B12 deficiency.
ADVIA Centaur and all associated marks are trademarks of Siemens Healthcare Diagnostics Inc. or its affiliates.
1. de Benoist B. Conclusions of a WHO Technical Consultation on folate and vitamin B12 deficiencies. Food Nutr Bull 2008;29:S238-44.
2. Baik HW, Russell RM. Vitamin B12 deficiency in the elderly. Annu Rev Nutr 1999;19:357-77.
3. Forman PD, Becker K. B12 (Cobalamin) Deficiency. Cortlandt Forum 2006;19:86-8.
4. Herrmann W, Obeid R. Causes and early diagnosis of vitamin B12 deficiency. Dtsch Arztebl Int 2008;105:680-5.