Macro vitamin B12: an underestimated threat

Background The correct identification of the macro-B12 interference (macroforms) is paramount to avoid potential erroneous clinical decisions. Our objectives were to determine whether immunoassays are affected by the presence of macro-B12 and to validate a polyethylene glycol (PEG) precipitation procedure to detect it. Methods Sixty-two serum samples obtained from healthy volunteers were analyzed to determine recovery and reference intervals (RIs) following PEG precipitation. Thereafter, 50 serum samples with very high levels of B12 (>1476 pmol/L) were randomly selected to search for macro-B12 interferences. Serum samples obtained from healthy volunteers and related PEG aliquots were analyzed on a $ Cobas^{®} $ immunoassay. Patients’ samples were analyzed on both $ Cobas^{®} $ and $ Architect^{®} $ immunoassays. Finally, samples suspected to contain macro-B12 were analyzed by size-exclusion chromatography (SEC) to confirm the presence of macro-B12. Results Recovery and post-PEG RIs determined on a Cobas $ 8000^{®} $ in healthy volunteers ranged from 68.3% to 108.4% and from 122.1 to 514.4 pmol/L, respectively. Fifteen samples (30%) were found to show macro-B12 while using the recovery criteria, and nine samples (18%) while using the post-PEG RI. The other immunoassay ran on the Architect $ i2000^{®} $ was also affected by the presence of macro-B12. Size-exclusion chromatography studies confirmed the presence of macro-B12 (immunoglobulin-B12 complexes). Conclusions The prevalence of macro-B12 in elevated B12 samples is high. We suggest to systematically screen for the presence of macro-B12 with PEG precipitation procedure in samples with elevated B12 levels to avoid potential misdiagnosis or harmful clinical consequences..

Medienart:

Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:58

Enthalten in:

Clinical chemistry and laboratory medicine - 58(2019), 3 vom: 30. Okt., Seite 408-415

Sprache:

Englisch

Beteiligte Personen:

Soleimani, Reza [VerfasserIn]
Favresse, Julien [VerfasserIn]
Roy, Tatiana [VerfasserIn]
Gruson, Damien [VerfasserIn]
Fillée, Catherine [VerfasserIn]

Links:

Volltext [lizenzpflichtig]

Anmerkungen:

©2020 Walter de Gruyter GmbH, Berlin/Boston

doi:

10.1515/cclm-2019-0999

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

OLC2142194370