This month, we have three ‘Articles of the month’. The reason for this selection is an email which we received from a doctor stating, ”I only give B12 injections to people who are anaemic and have antibodies against intrinsic factor."

Although vitamin B12 is an under-researched topic (which CluB-12 aims to correct), we selected the following three papers, in which the authors describe how they assessed the presence of IF antibodies in people with B12 deficiency.

What are the main findings of these papers?
In a study of 62 people with Biermer's disease (another name for pernicious anaemia) in France (defined as B12 deficiency with either anaemia, atrophic gastritis, or severe neurological symptoms), 29 (47%) had detectable anti-IF antibodies when the authors used the DiaSorin assay (measurement method). When they repeated the measurements using other assays, such as those from Dxl, Aeskulisa, or BioAdvance, only 16, 12, and 12 people out of 62, respectively, tested positive for anti-IF antibodies.

A study in Poland included 124 people with proven pernicious anaemia. Of these, only 38 (30%) had antibodies to intrinsic factor (measured w. EliA, Thermo Fisher, Germany).

A study in Spain examined 5468 primary care patients out of whom 77 people had SEVERE vitamin B12 deficiency, defined as a serum B12 level below 74 pmol/L. A total of 44 patients (57%) had anti-parietal cell antibodies, whereas only 14% (11 of the 77) had antibodies to intrinsic factor (measured w. ELISA, Euroimmun, Germany). Worse still, only 32% had anaemia. The study does not mention the final diagnosis of these 77 unfortunate individuals. Given that around 1% of the population in Spain follows a plant-based diet, it is possible that some of these people had a B12 deficiency due to insufficient B12 intake, thus unrelated to the presence or absence of IF antibodies. Nevertheless, they all had a severe deficiency.

Key takeaway: Depending on the study, between 14 and 47% of people with PA had IF antibodies, but differences between assays may result in much lower percentages. The doctor who only treats people with B12 injections if they have anaemia with antibodies to intrinsic factor is, unfortunately, leaving many people with overt B12 deficiency untreated.

Links:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/jcla.20272
https://www.degruyterbrill.com/document/doi/10.1515/cclm-2019-0749/html
https://www.mp.pl/paim/issue/article/15094/