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Active B12: a rapid, automated assay for holotranscobalamin on the Abbott AxSYM analyzer.
Clin Chem. 2008 Mar; 54(3):567-73.CC

Abstract

BACKGROUND

Conventional tests for vitamin B(12) deficiency measure total serum vitamin B12, whereas only that portion of vitamin B12 carried by transcobalamin (holotranscobalamin) is metabolically active. Measurement of holotranscobalamin (holoTC) may be more diagnostically accurate for detecting B(12) deficiency that requires therapy. We developed an automated assay for holoTC that can be used on the Abbott AxSYM immunoassay analyzer.

METHODS

AxSYM Active B12 is a 2-step sandwich microparticle enzyme immunoassay. In step 1, a holoTC-specific antibody immobilized onto latex microparticles captures holoTC in samples of serum or plasma. In step 2, the captured holoTC is detected with a conjugate of alkaline phosphatase and antiTC antibody.

RESULTS

Neither apoTC nor haptocorrin exhibited detectable cross-reactivity. The detection limit was < or = 0.1 pmol/L. Within-run and total imprecision (CV ranges) were 3.4%-5.1% and 6.3%-8.5%, respectively. Assay CVs were < 20% from at least 3 pmol/L to 107 pmol/L. With diluted serum samples, measured concentrations were 104%-114% of the expected values in the working range of the assay. No interference from bilirubin, hemoglobin, triglycerides, erythrocytes, rheumatoid factor, or total protein was detected at expected (abnormal) concentrations. A comparison of the AxSYM Active B12 assay with a commercial RIA for holoTC yielded the regression equation: AxSYM = 0.98RIA + 4.7 pmol/L (S(y x), 11.4 pmol/L; n = 204). Assay throughput was 45 tests/h. A 95% reference interval of 19-134 pmol/L holoTC was established with samples from 292 healthy individuals.

CONCLUSIONS

The AxSYM Active B12 assay allows rapid, precise, sensitive, specific, and automated measurement of human holoTC in serum and plasma.

Authors+Show Affiliations

Axis-Shield Diagnostics, Ltd., Dundee, Scotland, UK.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

18178666

Citation

Brady, Jeff, et al. "Active B12: a Rapid, Automated Assay for Holotranscobalamin On the Abbott AxSYM Analyzer." Clinical Chemistry, vol. 54, no. 3, 2008, pp. 567-73.
Brady J, Wilson L, McGregor L, et al. Active B12: a rapid, automated assay for holotranscobalamin on the Abbott AxSYM analyzer. Clin Chem. 2008;54(3):567-73.
Brady, J., Wilson, L., McGregor, L., Valente, E., & Orning, L. (2008). Active B12: a rapid, automated assay for holotranscobalamin on the Abbott AxSYM analyzer. Clinical Chemistry, 54(3), 567-73. https://doi.org/10.1373/clinchem.2007.096784
Brady J, et al. Active B12: a Rapid, Automated Assay for Holotranscobalamin On the Abbott AxSYM Analyzer. Clin Chem. 2008;54(3):567-73. PubMed PMID: 18178666.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Active B12: a rapid, automated assay for holotranscobalamin on the Abbott AxSYM analyzer. AU - Brady,Jeff, AU - Wilson,Lesley, AU - McGregor,Lynda, AU - Valente,Edward, AU - Orning,Lars, Y1 - 2008/01/04/ PY - 2008/1/8/pubmed PY - 2008/5/14/medline PY - 2008/1/8/entrez SP - 567 EP - 73 JF - Clinical chemistry JO - Clin Chem VL - 54 IS - 3 N2 - BACKGROUND: Conventional tests for vitamin B(12) deficiency measure total serum vitamin B12, whereas only that portion of vitamin B12 carried by transcobalamin (holotranscobalamin) is metabolically active. Measurement of holotranscobalamin (holoTC) may be more diagnostically accurate for detecting B(12) deficiency that requires therapy. We developed an automated assay for holoTC that can be used on the Abbott AxSYM immunoassay analyzer. METHODS: AxSYM Active B12 is a 2-step sandwich microparticle enzyme immunoassay. In step 1, a holoTC-specific antibody immobilized onto latex microparticles captures holoTC in samples of serum or plasma. In step 2, the captured holoTC is detected with a conjugate of alkaline phosphatase and antiTC antibody. RESULTS: Neither apoTC nor haptocorrin exhibited detectable cross-reactivity. The detection limit was < or = 0.1 pmol/L. Within-run and total imprecision (CV ranges) were 3.4%-5.1% and 6.3%-8.5%, respectively. Assay CVs were < 20% from at least 3 pmol/L to 107 pmol/L. With diluted serum samples, measured concentrations were 104%-114% of the expected values in the working range of the assay. No interference from bilirubin, hemoglobin, triglycerides, erythrocytes, rheumatoid factor, or total protein was detected at expected (abnormal) concentrations. A comparison of the AxSYM Active B12 assay with a commercial RIA for holoTC yielded the regression equation: AxSYM = 0.98RIA + 4.7 pmol/L (S(y x), 11.4 pmol/L; n = 204). Assay throughput was 45 tests/h. A 95% reference interval of 19-134 pmol/L holoTC was established with samples from 292 healthy individuals. CONCLUSIONS: The AxSYM Active B12 assay allows rapid, precise, sensitive, specific, and automated measurement of human holoTC in serum and plasma. SN - 0009-9147 UR - https://www.unboundmedicine.com/medline/citation/18178666/Active_B12:_a_rapid_automated_assay_for_holotranscobalamin_on_the_Abbott_AxSYM_analyzer_ L2 - https://academic.oup.com/clinchem/article-lookup/doi/10.1373/clinchem.2007.096784 DB - PRIME DP - Unbound Medicine ER -