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Measurement of total Transcobalamin employing a commercially available assay for Active B12.
Clin Biochem. 2017 Dec; 50(18):1030-1033.CB

Abstract

INTRODUCTION

Vitamin B12 deficiency is mostly caused by insufficient gastro-intestinal absorption and in rare conditions by Transcobalamin (TC) deficiency. Unsaturated Transcobalamin (apoTC) can be measured by a binding assay using radiolabeled cobalamin. The Active B12 test analyzes saturated Transcobalamin (holoTC) and we hypothesize that this test can be used to measure total TC by additional in vitro saturation with cobalamin.

METHODS

Serum was saturated in vitro (16 times dilution) with a cyanocobalamin solution and total TC was selectively measured with the Abbott Active B12 test. ApoTC was calculated by subtracting endogenous holoTC from total TC after correction for dilution. Linearity was determined with a pool serum dilution series. Precision was investigated according to the CLSI EP15 protocol. Method comparison was performed against a binding assay using radiolabeled cobalamin. Reference values were determined in 100 healthy controls.

RESULTS

The method was linear in the range of 240 to 1933pmol/L (R2=0.997, lack of fit F=1.61). Precision of low- and high-pool total TC in serum were; 5.2% and 4.3% respectively. Method comparison against a radiolabeled cobalamin binding assay showed a proportional bias of 30% (y=0.70x+126). Total TC reference values were determined at 500-1276pmol/L.

CONCLUSION

We describe a rapid method to quantify total TC, which can be implemented on routine platforms using commercial Active B12 tests. In addition, apoTC can be assessed by subtracting endogenous holoTC concentration which can be measured in the same run, securing the same calibration level for all three parameters (holoTC, apoTC and total TC). This method is applicable in clinical diagnostics and in larger epidemiological studies.

Authors+Show Affiliations

Erasmus MC University Medical Center Rotterdam, Department of Clinical Chemistry, PO box 2040, 3000 CA Rotterdam, The Netherlands.Erasmus MC University Medical Center Rotterdam, Department of Clinical Chemistry, PO box 2040, 3000 CA Rotterdam, The Netherlands.Erasmus MC University Medical Center Rotterdam, Department of Clinical Chemistry, PO box 2040, 3000 CA Rotterdam, The Netherlands.Erasmus MC University Medical Center Rotterdam, Department of Clinical Chemistry, PO box 2040, 3000 CA Rotterdam, The Netherlands. Electronic address: s.heil@erasmusmc.nl.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28823760

Citation

Griffioen, Pieter H., et al. "Measurement of Total Transcobalamin Employing a Commercially Available Assay for Active B12." Clinical Biochemistry, vol. 50, no. 18, 2017, pp. 1030-1033.
Griffioen PH, van Dam-Nolen DHK, Lindemans J, et al. Measurement of total Transcobalamin employing a commercially available assay for Active B12. Clin Biochem. 2017;50(18):1030-1033.
Griffioen, P. H., van Dam-Nolen, D. H. K., Lindemans, J., & Heil, S. G. (2017). Measurement of total Transcobalamin employing a commercially available assay for Active B12. Clinical Biochemistry, 50(18), 1030-1033. https://doi.org/10.1016/j.clinbiochem.2017.08.009
Griffioen PH, et al. Measurement of Total Transcobalamin Employing a Commercially Available Assay for Active B12. Clin Biochem. 2017;50(18):1030-1033. PubMed PMID: 28823760.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Measurement of total Transcobalamin employing a commercially available assay for Active B12. AU - Griffioen,Pieter H, AU - van Dam-Nolen,Dianne H K, AU - Lindemans,Jan, AU - Heil,Sandra G, Y1 - 2017/08/16/ PY - 2017/05/29/received PY - 2017/08/15/revised PY - 2017/08/16/accepted PY - 2017/8/22/pubmed PY - 2017/12/19/medline PY - 2017/8/22/entrez KW - Active B12 KW - Vitamin B12 KW - apo-Transcobalamin KW - holo-Transcobalamin SP - 1030 EP - 1033 JF - Clinical biochemistry JO - Clin Biochem VL - 50 IS - 18 N2 - INTRODUCTION: Vitamin B12 deficiency is mostly caused by insufficient gastro-intestinal absorption and in rare conditions by Transcobalamin (TC) deficiency. Unsaturated Transcobalamin (apoTC) can be measured by a binding assay using radiolabeled cobalamin. The Active B12 test analyzes saturated Transcobalamin (holoTC) and we hypothesize that this test can be used to measure total TC by additional in vitro saturation with cobalamin. METHODS: Serum was saturated in vitro (16 times dilution) with a cyanocobalamin solution and total TC was selectively measured with the Abbott Active B12 test. ApoTC was calculated by subtracting endogenous holoTC from total TC after correction for dilution. Linearity was determined with a pool serum dilution series. Precision was investigated according to the CLSI EP15 protocol. Method comparison was performed against a binding assay using radiolabeled cobalamin. Reference values were determined in 100 healthy controls. RESULTS: The method was linear in the range of 240 to 1933pmol/L (R2=0.997, lack of fit F=1.61). Precision of low- and high-pool total TC in serum were; 5.2% and 4.3% respectively. Method comparison against a radiolabeled cobalamin binding assay showed a proportional bias of 30% (y=0.70x+126). Total TC reference values were determined at 500-1276pmol/L. CONCLUSION: We describe a rapid method to quantify total TC, which can be implemented on routine platforms using commercial Active B12 tests. In addition, apoTC can be assessed by subtracting endogenous holoTC concentration which can be measured in the same run, securing the same calibration level for all three parameters (holoTC, apoTC and total TC). This method is applicable in clinical diagnostics and in larger epidemiological studies. SN - 1873-2933 UR - https://www.unboundmedicine.com/medline/citation/28823760/Measurement_of_total_Transcobalamin_employing_a_commercially_available_assay_for_Active_B12_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0009-9120(17)30528-3 DB - PRIME DP - Unbound Medicine ER -