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

Fabrizia Bamonti, Giovanna Antonella Moscato, Cristina Novembrino, Dario Gregori, Claudia Novi, Rachele De Giuseppe, Claudio Galli, Valentina Uva, Silvia Lonati, Rita Maiavacca

Research output: Contribution to journalArticlepeer-review

Abstract

Background: A reliable early marker is required for diagnosis of cobalamin deficiency. We calculated an appropriate holotranscobalamin (HoloTC) cut-off point for identifying cobalamin deficiency using an immunoenzymatic assay. Methods: Determination of the cut-off threshold and correlation between HoloTC and the other diagnostic parameters routinely used for vitamin B12 deficiency [total vitamin B12 (tB12), folate, homocysteine] were measured in 250 routine blood specimens from 107 men (mean age 59.0±18.8 years) and 143 women (mean age 54.2±23.1 years). The inclusion criterion was serum tB12 concentration ≤221 pmol/L. Results: Analytical performance results agreed with those reported by others. A weak correlation (R=0.42) was found between HoloTC and tB12. A 40 pmol/L cut-off threshold was chosen for HoloTC and the associated sensitivity and specificity was 0.86 and 0.66, respectively. Out of 250 tested samples, 126 showed tB12 concentrations 139-221 pmol/L (gray zone, GZ) and 124 had tB12 concentrations 12 values.

Original languageEnglish
Pages (from-to)249-253
Number of pages5
JournalClinical Chemistry and Laboratory Medicine
Volume48
Issue number2
DOIs
Publication statusPublished - Feb 1 2010

Keywords

  • Analytical performance
  • Holotranscobalamin
  • Immunoenzymatic assay
  • Vitamin B

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, medical

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