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Macro vitamin B12: an underestimated threat
Reza Soleimani1, Julien Favresse1, Tatiana Roy2
1Department of Laboratory Medicine, Cliniques Universitaires St-Luc and Université catholique de Louvain, Brussels, Belgium.
Clinical Chemistry and Laboratory Medicine
|October 31, 2019
Summary
Macro-B12 interference, or macroforms, can lead to incorrect clinical decisions. A polyethylene glycol (PEG) precipitation method effectively detects macro-B12 in samples with elevated vitamin B12 levels, preventing misdiagnosis.
Area of Science:
- Clinical Chemistry
- Immunochemistry
- Laboratory Medicine
Background:
- Accurate identification of macro-B12 interference (macroforms) is critical for preventing erroneous clinical decisions.
- Immunoassays may be susceptible to interference from macro-B12, necessitating reliable detection methods.
Purpose of the Study:
- To investigate the impact of macro-B12 on common immunoassays.
- To validate a polyethylene glycol (PEG) precipitation procedure for detecting macro-B12.
Main Methods:
- Analyzed serum samples from healthy volunteers to establish recovery and reference intervals (RIs) post-PEG precipitation.
- Evaluated 50 serum samples with very high vitamin B12 levels (>1476 pmol/L) for macro-B12 interference using Cobas® and Architect® immunoassays.
- Confirmed macro-B12 presence using size-exclusion chromatography (SEC).
Main Results:
- Post-PEG RIs on Cobas 8000® ranged from 122.1 to 514.4 pmol/L, with 30% of samples showing macro-B12 by recovery criteria and 18% by post-PEG RI.
- Both Cobas® and Architect® immunoassays were affected by macro-B12 interference.
- SEC confirmed macro-B12 as immunoglobulin-B12 complexes.
Conclusions:
- Macro-B12 interference is prevalent in samples with elevated vitamin B12 levels.
- Systematic screening for macro-B12 using PEG precipitation in samples with high B12 is recommended to avoid misdiagnosis and adverse clinical outcomes.
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