Background and objectives: Vitamin B12 is an essential nutrient that plays crucial roles in the human body. B12 deficiency primarily affects the hematopoietic system, but its effects extend to other tissues and organs, most notably the nervous system. The neurological symptoms of vitamin B12 deficiency are non specific and can be irreversible. Holotranscobalamin (Holo-TC) also called as active B12 has been suggested as sensitive marker for early diagnosis of B12 deficiency; therefore measurement of Holo-TC may be useful for taking therapeutic measures before neurological damage of vitamin B 12 deficiency develops. Methods: We tested serum samples of 50 cases for hemoglobin levels, MCV and total vitamin B12 assay. We divided them into two groups and also tested for Holo-TC.Group: 1) Hemoglobin above 11.0 gm %, MCV between 85–96 fl and serum B 12 in the range of 200-300 pmol/L. Group: 2) Hemoglobin less than 11.0 gm % and serum B12 less than 200 pmol/L. MCV and hemoglobin was measured by Sysmex KX-21 five part differential cell counter. PBF of all subjects was examined for evidence of hyper segmentation. Cases having history of any disease were not included in the study. Results: Group 1 cases were having total serum B 12 level in normal range but Holo- TC value of these cases was found decreased suggestive of early vitamin B12 deficiency. Group 2 cases were having a low value of serum B12 with markedly low value of Holo-TC suggesting that value of Holo-TC decreases with decrease in serum B 12 levels. Conclusions: Data present in this study show correlation between Serum Vitamin B12 and Holo-TC results. In majority of cases significant correlation was observed between the two indices. We predict that Holo-TC is a good marker for early diagnosis of vitamin B12 deficiency.

Keywords: Hemoglobin; MCV; Vitamin B12; Holo-TC.