engleski

DIAGNOSTIC VALUE OF HOLOTRANSCOBALAMIN IN ASSESSMENT OF VITAMIN B12 DEFICIENCY

Background Different neurological manifestations could be a consequence of vitamin B12 deficit, even when vitamin B12 concentrations are within reference intervals. In theory, measurement of amount of vitamin B12 available for the cells, known as holotranscobalamin, could be a more sensitive indicator of B12 deficiency in such cases. The aim of the study was to examine the potential usefulness of holotranscobalamin in assessment of vitamin B12 deficiency. Methods The study included 54 subjects who were divided into two groups according to the homocysteine values: 31 patients with elevated homocysteine values (>15 µmol/L) and with neurological symptoms and 23 patients with normal homocysteine values and different diagnoses which represented controls. All subjects in both groups had vitamin B12 concentrations between 138 and 300 pmol/L. Serum samples were collected according to a standard operating procedure using a blood activator tubes (Becton-Dickinson, Eysins, Switzerland). Vitamin B12, holotranscobalamin and homocysteine were measured with chemiluminescent microparticle immunoassay on the Architect i1000SR analyzer (Abbott Diagnostics, Lake Forest, IL, USA). The results were processed using MedCalc Software version 12.4.0 (MedCalc Software, Mariakerke, Belgium). ROC curve was used for sensitivity and specificity testing, while Mann-Whitney test was used for groups comparison. For testing of the association between variables, Spearman’s rank correlation test was used. Results Patients with neurological simptoms and hiperhomocysteinemia had only a bit lower median values of holotranscobalamin (50.4 pmol/L vs 54.6 pmol/L ; P=0.896). Using homocysteine as a discriminating variable between the groups we obtained similar AUC values for vitamin B12 (AUC=0.596) and holotrancobalamin (AUC=0.511). We also found moderate correlation between holotranscobalamin and vitamin B12 (r=0.440 ; P<0, 001). Conclusion Our study shows that holotranscobalamin is not a more sensitive indicator of vitamin B12 deficiency than vitamin B12. Holotranscobalamin and vitamin B12, separately or in combination, have almost equal diagnostic efficiency as early indicators of the vitamin B12 deficiency

holotranscobalamin, vitamin B12, deficiency

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