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Immune complexes and persistent high levels of serum vitamin B 12
Author(s) -
Remacha A. F.,
Zapico E.,
Sarda M. P.,
Rojas E.,
Simó M.,
Remacha J.,
Homs R.,
Queralto J. M.
Publication year - 2014
Publication title -
international journal of laboratory hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.705
H-Index - 55
eISSN - 1751-553X
pISSN - 1751-5521
DOI - 10.1111/ijlh.12131
Subject(s) - peg ratio , vitamin , vitamin b , prospective cohort study , polyethylene glycol , medicine , size exclusion chromatography , chemistry , antibody , immune system , immunology , biochemistry , enzyme , finance , economics
Summary Introduction Patients with persistent high levels of serum vitamin B 12 were often referred to Hematology departments. In this study, characteristic of patients with serum vitamin B 12 levels higher than 2500 pmol/L (high B 12) were studied. Methods Prevalence of high B 12 was evaluated during a 10‐month period. Samples with high B 12 were incubated with polyethylene glycol ( PEG ) and a new measurement of vitamin B 12 was carried out using the supernatant. As a pilot study, 26 frozen samples with high B 12 were evaluated for changes in vitamin B 12 after PEG . Moreover, a prospective study was carried out during three consecutive months. Size exclusion chromatography was employed to demonstrate the presence of immune complexes ( IC s) with plasma vitamin B 12‐binding proteins in some serum samples with high B 12. Results Prevalence of high B 12 was 1.3%. Results from 26 frozen samples and from a prospective study (28 cases) showed that undergoing vitamin B 12 treatment was the main cause of high B 12. However, IC s were detected in 10 frozen samples and in seven cases (25%) of the prospective study, respectively. Serum vitamin B 12 decreased to normal values after precipitation with PEG , and size exclusion chromatography confirmed IC s. An association with autoimmune or hematological disorders was observed. Conclusions In patients with repeatedly high B 12 levels, IC s were detected in approximately 25% of samples. Precipitation with PEG is an easy method to confirm the presence of IC s and to evaluate serum vitamin B 12 levels in these patients.