Was anaemia and/or macrocytosis present at the time of diagnosis?

We frequently hear from patients that many doctors are still not fully aware of the fact that the neurological and psychiatric symptoms of a vitamin B12 deficiency often occur without the existence of anaemia and/or macrocytosis. The fact that a vitamin B12 deficiency without anaemia is indeed serious is also insufficiently known. Neurological symptoms can already be (very) serious, with risk of permanent damage, before anaemia develops. This was already described in scientific literature for the first time in 1905.

Only 28 % of the respondents in this survey (who knew their results) had anaemia and 15 % had enlarged red blood cells (macrocytosis). In only 8 % both anaemia and macrocytosis were present. In 65 % both anaemia and macrocytosis were absent, which is twice as high as the 33 % often quoted in the literature. Two articles with more information can be found here and here.

Were possible causes tested, which tests were done, what were the results & is it familial?


In only 29.5 % of the respondents possible causes were tested for.

Tests which were done:

  • serum test for intrinsic factor antibodies, parietal cell antibodies, Helicobacter pylori & coeliac disease
  • gastroenterological examinations of stomach/bowels including gastroscopy, ultrasound & stool analysis.

Serum antibodies tests and gastroscopy were mentioned most frequently.

That there are many possible causes for a vitamin B12 deficiency is insufficiently known by medical practitioners. In many patients where a possible cause was looked for, only one cause was examined.
In almost 50 % of the patients who had been examined for a cause, a cause was found. It is often not tested because the doctor thinks that there is no cause to be found. These results show that it certainly makes sense to test for causes.
A number of causes can be treated (such as coeliac disease and Helicobacter pylori) thus facilitating the (partial) recovery of vitamin B12 absorption. Testing for various possible causes should therefore be performed more often.

The most mentioned cause, by far, for vitamin B12 deficiency:

  • Pernicious anaemia / intrinsic factor antibodies / parietal cell antibodies.

Also mentioned more often:

  • Crohn’s disease / inflammation of the small intestine
  • Atrophic gastritis
  • Helicobacter pylori
  • Drug use (gastric acid inhibitors / metformin)
  • Operations relating to ileum or stomach
  • Lack of B12 in the diet
  • Gastric Bypass
  • Intestinal parasites
  • Coeliac disease

35 % of the patients have at least one other family member with a vitamin B12 deficiency. These are usually a parent, child, sibling or grandparent.

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