Holo-Transcobalamin Concentration and Transcobalamin Saturation Reflect Recent Vitamin B12 Absorption Better than Does Serum Vitamin B12

Determination of serum holotranscobalamin concentrations with the AxSYM active B12 assay: cut-off point evaluation in the clinical laboratory

“…Measurement of serum HoloTC concentration may prove helpful in evaluating the absorption of vitamin B 12 as HoloTC concentrations and TC saturation reflect recent vitamin B 12 absorption better than serum tB 12 (21). However, according to Chen et al, HoloTC concentrations most probably reflect vitamin B 12 status independently of its recent absorption (22).…”

Fraction of Total Plasma Vitamin B12 Bound to Transcobalamin Correlates with Cognitive Function in Elderly Latinos with Depressive Symptoms

“…The use of holoTC in a ratio to assess B12 status has been reported, but usually in the context of the percentage of total TC that has bound B12 or percent TC saturation (a calculated value that is distinct from the holoTC/ B12 ratio). Percent TC saturation, in combination with holoTC, has been suggested as a better measure of change in B12 status than holoTC alone (10,11,38 ). Whereas this information may be useful in diagnosing malabsorption, holoTC/B12 may better reflect the availability of circulating B12 to tissues, and therefore intracellular B12 status.…”

Holotranscobalamin and methylmalonic acid as prognostic markers following an acute myocardial infarction

“…Cobalamin-linked TC, termed holotranscobalamin (holoTC), constitutes about one-third and represents the physiologically active part, capable of entering cells through receptor-mediated endocytosis. This part of total cobalamin has recently been demonstrated to be an early marker of changes in cobalamin homeostasis (Nexo et al, 2002;Bor et al, 2004;Chen et al, 2005;Hvas and Nexo, 2005). Values below the lower reference limit have actually been found to appear with serum levels of total vitamin B 12 as high as 241 pmol/l.…”