Serum Holotranscobalamin and Methylmalonic Acid as Early Markers of Vitamin B12 Deficiency in Pregnant Females

Abstract Background: Screening for Vitamin B 12 deficiency in pregnancy is not routinely done in antenatal care. Serum Vitamin B 12 assay has low sensitivity and specificity; therefore, this study was conducted to assess the usefulness of holotranscobalamin (HoloTC) and methylmalonic acid (MMA) as early markers of functional Vitamin B 12 deficiency in pregnant females. Objective: The objective of this study was to estimate the levels of HoloTC and MMA in pregnant females and correlate the levels of serum HoloTC and MMA with the levels of Vitamin B 12 in pregnant females. Materials and Methods: Blood samples from 100 pregnant females in the first trimester were collected. Vitamin B 12 was measured by chemiluminescence method, and serum HoloTC and MMA were measured by enzyme immunoassay. Results: Vitamin B 12 levels were reduced (<200 pg/ml) in 90% pregnant females. To define Vitamin B 12 deficiency (<200 pg/ml), a cutoff ≤23.78 ng/ml and ≥11.67 ng/ml were defined for HoloTC and MMA, respectively, on receiver operating characteristic analysis. Out of 100 cases, 50% cases had HoloTC levels below the cutoff values, and among these 82% had Vitamin B 12 deficiency as well. Out of 100 cases, 24 had MMA concentration above the cutoff value and all these 24 cases had Vitamin B 12 deficiency. However, 9 out of 10 cases with normal Vitamin B 12 showed low HoloTC but normal MMA values. Conclusions: HoloTC and MMA could be a better diagnostic marker than Vitamin B 12 to detect subclinical deficiency.