Vitamin B12 (cobalamin) plays an important role in DNA syntesis and neurologic function. Deficiency can lead to a wide spectrum of hematologic and neuropsychiatric disorders that can often be reserved by early diagnosis and prompt treatment.1
The primary analysis of vitamin B12 deficiency is the measurement of serum cobalamin (vitamin B12).2 There commonly used tests measure total vitamin B12, which is found in blood bound to two carrier poteins: haptocorrin and transcobalamin. When vitamin B12 is bound to transcobalamin it is referred to as holotranscobalamin (holoTC). HoloTC contains the biologically available cobalamin as only holoTC promotes the uptake of cobalamin by all cells via specific receptors. In comparison, approximately 80% of the circulating cobalamin that is carried by haptocorrin is considered metabolically inert because no cellular receptors exist (with the exception of receptors found in the liver.)3
The Siemens Healthineers Active-B12 (AB12) assay offered on the Atellica® IM Analyzer and ADVIA Centaur® Immunoassay Systems measures holo TC in the blood – the only form of vitamin B12 that is taken up and used by cells of the body.