WHAT IS VITAMIN B12, UNSATURATED BINDING CAPACITY (UBC) TEST?
Vitamin B12 (cyanocobalamin) is a water-soluble vitamin obtained from dietary animal sources that are necessary for proper deoxyribonucleic acid (DNA) synthesis. It is absorbed from the gastrointestinal tract only when bound by intrinsic factor glycoprotein secreted from the stomach’s parietal cells. After absorption, it is transported in the bloodstream by transcobalamin-binding proteins, primarily transcobalamin I. In this test, the intrinsic factor is added to a mixture of the client’s serum and radiolabeled vitamin B12. The mixture is incubated, and then the fraction of bound, radiolabeled vitamin B12 is measured by a scintillation counter after removal of the unbound vitamin. The results are an indication of the level of transcobalamin-binding proteins, which are known to be elevated in certain conditions (listed above).