Who diagnosed & treated the deficiency?

In more than a quarter of the cases the patient asked the doctor to test for vitamin B12.

In the almost 21 % of the patients whose deficiency was not diagnosed by a GP or specialist (but by the company doctor, midwife or alternative practitioner, for example) most also asked themselves for vitamin B12 to be tested.

Mentioned in “Other” category:

  • Alternative doctor or therapist
  • Private blood tests requested by patient themselves
  • Psychiatrist
  • Company Doctor
  • Midwife

Was the test just B12 or Active B12 and what were the results?

Serum B12 is (still) the standard test for the diagnosis of a vitamin B12 deficiency. There are concerns about this test.

Active B12 is evidently still not well known and requested relatively infrequently.

When patients indicated that they did not know which test they had, it was evident from the next question which asked for their result (if they knew it), that it was the serum B12.

What was the value of serum B12 in pmol/L?

The reference values for serum B12 may differ from laboratory to laboratory, usually because of different test methods.
In the international scientific literature 150 pmol/L is generally used as the lowest reference value. Below this level a deficiency is indicated. This lowest value indicates a specificity of > 95%.
It is insufficiently known that there is a large grey area in reference values where a deficiency is possible and that the value of serum B12 can be either false low or false high.

More information about this can be read here. In the case of obvious symptoms and a low normal value of serum B12, MMA and homocysteine should also be tested.

What was the value of active B12?

The official reference value for Active B12 in the Netherlands is 21 pmol/L.
In international scientific literature it is generally 35 pmol/l. Values below 35 pmol/L are very likely to indicate a deficiency.
Between the 35 and 50 pmol/l is seen as a grey area, which indicates further testing for at least MMA. An article was published recently which even mentioned a grey area up to 75 pmol/L.

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