Diagnosing Vitamin B12 Deficiency and Pernicious Anaemia

From the very beginning this charity has been made aware that there are serious problems with patients receiving an early diagnosis that will explain their symptoms. The problem of getting an accurate and quick diagnosis were the subject of many discussions on social media and on our online forum and its extent became clear when the results of our survey 1 were published.
The survey asked nearly 900 of our members whether they were given an initial false diagnosis and how long they had waited for an explanation of their symptoms. The results were:
  • 44% were initially wrongly diagnosed as having some other problem
  • 22% had to wait 2 years for a correct diagnosis,
  • 19% for 5 years
  • 4% for 10 years
  • 14% waited 10 years or more.

There are several reasons why there are problems with patients getting quickly and accurately diagnosed:

  • Firstly, doctors are not ‘looking’ for B12 Deficiency. That’s why it’s important that you ask your doctor to check your B12 levels.
  • Secondly the B12 test is not part of the Full Blood Count that doctors routinely request. Instead doctors look for any enlarged red blood cells that would indicate possible B12 deficiency. However, only around 60% of patients with a B12 deficiency will have enlarged red blood cells (macrocytosis) 2, 3.
    Ask for your B12 to be tested if your full blood count doesn’t show any signs of enlarged red blood cells.
  • If you are taking any sorts of B12 Supplement (such as a multivitamin tablet) do tell your doctor about this. Also, be aware that taking folic acid will prevent your red blood cells becoming enlarged so be sure to tell your doctor if you are taking any form of folic acid.
  • There are serious shortcomings with the current test used to determine B12 status in patients. The current test, the Combined Binding Luminescence Test is giving false high results in between 22 and 35% of patients (depending on the manufacturer of the test machine). 4 If your test results come back as normal or borderline you may want to ask your doctor for a Therapeutic Trial of B12 injections to judge whether you feel better.

New Guidelines

The recently updated Guidelines on Cobalamin and Folic Acid by the British Committee for Standards in Haematology 5 state the following:

  • The clinical picture is the most important factor in assessing the significance of test results assessing cobalamin status since there is no ‘gold standard’ test to define deficiency.
  • Definitive cut-off points to define clinical and subclinical deficiency states are not possible, given the variety of methodologies used and technical issues, and local reference ranges should be established.
  • In the presence of discordance between the test result and strong clinical features of deficiency, treatment should not be delayed to avoid neurological impairment.

Whatever the outcome of the tests it is a good idea to ask for a copy of the results so that you can make an informed decision about your next step – the treatment.

Key Points:

  • Some doctors believe that the current threshold for determining B12 Deficiency is far too low 6 and that there is a link between the speed of brain shrinkage and B12 levels.7
  • You cannot overdose on vitamin B12 as it is a water soluble vitamin.

When you go to your Health Professional it will be useful for you to go fully informed. So please feel free to use the items we have created below.

We have an ‘Update for Health Professionals‘ leaflet and ‘Helpful Info for your GP/Consultant’ available in our members-only library with more information for your GP/Consultant.

Testing for Pernicious Anaemia , suggestions for you and your GP – It will be useful for you to print and read this.

Symptom Checklist (PDF) – This is useful to print, read and fill in.

To read our extended information on the Diagnosis of Pernicious Anaemia, please login or become a member.
Members will see the extended information-pages in the main menu below Diagnosis.

  1. May 2014
  2. Patient Journeys: diagnosis and treatment of Pernicious Anaemia: Hooper M V, Hudson P, et al; British Journal of Nursing, 2014, Vol. 23, No 7
  3. Beck W S. Neuropsychiatric consequences of cobalamin deficiency. Advanced Institute of Medicine, 1991; 36: 33-56
  4. Lindenbaum J, Healton EB et al. Neuropsychiatric disorders caused by cobalamin deficiency in the absence of anemia or macrocytosis. New England Journal of Medicine 1988; 318(26): 1720-1728
  5. Carmel R, Agrawal Y P. Failures of Cobalamin Assays and Pernicious Anaemia. New England Journal of Medicine, 2012, 367(4): 266.
    See also David T. Yang, Rachel J. Cook, Spurious Elevations of Vitamin B12 with Pernicious Anemia: New England Journal of Medicine; 366;18
  6. Smith & Refsum; Do We Need To Reconsider Blood Level of Vitamin B12?  Journal of Internal Medicine, 2012;271(2): 179-182
  7. Douaud G, Refsum H, et al: Preventing Alzheimer’s disease-related gray matter atrophy by B-vitamin treatment http://www.ncbi.nlm.nih.gov/pubmed/23690582

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