Comparison of four automated serum vitamin B12 assays
-
Emre İspir
,
Muhittin A. Serdar
Abstract
Background: Diagnosis of vitamin B12 deficiency is generally based on the measurement of serum vitamin B12 levels. However, in selected cases functional indices of vitamin B12, such as methylmalonic acid (MMA) and homocysteine (HCY), are needed. Here we compare the performance of four automated total vitamin B12 assays and also investigate how these assays relate to functional indices of vitamin B12 status.
Methods: Total vitamin B12, MMA and HCY were measured in 69 serum samples from routine vitamin B12 assay requests. Serum vitamin B12 analysis was performed using four different immunoassay autoanalyzers: DxI 800 Unicel (Beckman Coulter, USA), ADVIA Centaur XP (Siemens Diagnostics, Tarrytown, NY, USA), Roche Cobas E601 (Roche Diagnostics, Germany), Architect i2000sr (Abbott Laboratories, Abbott Park, IL, USA). Serum MMA levels were determined by liquid chromatography-mass spectrometry (LC-MS) and serum homocysteine levels were determined by high pressure liquid chromatography (HPLC) methods.
Results: Four immunoassay methods were comparable and correlated with each other. Correlation coefficients (r) ranged from 0.898 to 0.987, p<0.001. Highest correlation was observed between Roche Cobas – Architect i2000sr and poorest correlation was observed between DxI 800 Unicel – ADVIA Centaur comparison. DxI 800 Unicel assay demonstrated high mean bias [–122 pg/mL (–616–125 pg/mL)] and a concordance correlation coefficient (CCC) of 0.9161, lower than the others. MMA and HCY were correlated with the vitamin B12 results. The correlation coefficients with their 95% CI indicated that there was no statistically significant difference between the four methods according to their relationship with MMA and HCY.
Conclusions: Total B12 assays correlate very well with each other. However, results of DxI 800 Unicel were lower compared to the other three autoanalyzers. All total vitamin B12 methods show similar relationships with HCY and MMA. Standardization of serum vitamin B12 assays is still not completed and further standardization studies are needed. Laboratory professionals and clinicians should be aware of this disagreement between assay methods and they should use these tests as ancillary tests.
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©2015 by De Gruyter
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Articles in the same Issue
- Frontmatter
- Editorials
- Once upon a time: a tale of ISO 15189 accreditation
- A new integrated tool for assessing and monitoring test comparability and stability
- Liver-FibroSTARD checklist and glossary: tools for standardized design and reporting of diagnostic accuracy studies of liver fibrosis tests
- Reviews
- Thromboembolic risk in hematological malignancies
- A review of the cut-off points for the diagnosis of vitamin B12 deficiency in the general population
- Opinion Paper
- Permissible limits for uncertainty of measurement in laboratory medicine
- EFLM Position Paper
- Flexible scope for ISO 15189 accreditation: a guidance prepared by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group Accreditation and ISO/CEN standards (WG-A/ISO)
- Genetics and Molecular Diagnostics
- Evaluation of a low-cost procedure for sampling, long-term storage, and extraction of RNA from blood for qPCR analyses
- Application of real-time PCR of sex-independent insertion-deletion polymorphisms to determine fetal sex using cell-free fetal DNA from maternal plasma
- General Clinical Chemistry and Laboratory Medicine
- The Empower project – a new way of assessing and monitoring test comparability and stability
- Comparison of four automated serum vitamin B12 assays
- Combined indicator of vitamin B12 status: modification for missing biomarkers and folate status and recommendations for revised cut-points
- INR vs. thrombin generation assays for guiding VKA reversal: a retrospective comparison
- Determination of dabigatran in plasma, serum, and urine samples: comparison of six methods
- Simple high-throughput analytical method using ultra-performance liquid chromatography coupled with tandem mass spectrometry to quantify total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in urine
- Revival of physostigmine – a novel HPLC assay for simultaneous determination of physostigmine and its metabolite eseroline designed for a pharmacokinetic study of septic patients
- Relationship between antiphosphatidylserine/prothrombin and conventional antiphospholipid antibodies in primary antiphospholipid syndrome
- Reference Values and Biological Variations
- Relevance of EDTA carryover during blood collection
- Reference intervals for renal injury biomarkers neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 in young infants
- Cardiovascular Diseases
- NT-proBNP levels and their relationship with systemic ventricular impairment in adult patients with transposition of the great arteries long after Mustard or Senning procedure
- Letters to the Editors
- Troponin T measured with highly sensitive assay (hsTnT) on admission does not reflect infarct size in ST-elevation myocardial infarction patients receiving primary percutaneous coronary intervention
- Analytical challenges related to the use of biomarker ratios for the biological diagnosis of Alzheimer’s disease
- Serum brain injury biomarkers as predictors of mortality after severe aneurysmal subarachnoid hemorrhage: preliminary results
- Tumor markers assay by the Lumipulse G
- Real-world costs of laboratory tests for non-small cell lung cancer
- Impact of stopping vitamin K antagonist therapy on concentrations of dephospho-uncarboxylated Matrix Gla protein
- Practicability of fetal scalp blood sampling during labor using microtubes and a point-of-care (POC) lactate testing device: difficulty assessment, sampling time and failure rates
- Establishing objective analytical quality requirements in the IgE specific assay: a message in a bottle
- Bacteria on a peripheral blood smear as presenting sign of overwhelming post-splenectomy infection in a patient with secondary acute myeloid leukemia
