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Pernicious Anaemia Society
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Is Iron blood test the same as b12 blood test?

Hi all,

I hope someone can give me some clarification on this. I have yet to get a diagnosis of PA even though I have many symptoms and also a very long family history of PA.

I have up until now being medicating myself with sublingual's until my health started to decline so I decided to bite the bullet and ask to be retested. ( last bloods done over a year ago)

I have just spoken to the receptionist at the doctors for my results and she said my Iron levels should be in the range of 15-200 and mine were below 5.

I have an appointment to see the doctor on Friday and would like to go with the knowledge that I have had the correct test. ( I did have several done, full blood count, thyroid and a couple more but my memory is so shocking at the moment I don't remember what they were.

So could someone please confirm that the 'Iron' blood test was in-fact the b12 test I had requested?

Thank you in advance. :)

3 Replies

No, they're not the same.

A lack of either can cause anaemia, but the types of anaemia are totally different.

Iron deficiency causes microcytic (small cell) anaemia. The red blood cells are too small. B12 deficiency causes (large cell) anaemia. The red blood cells are too big.

If you had a full blood count then one thing they measured would be the Mean Cell Volume. An MCV less than 80 indicates microcytic anaemia, higher than 100 suggests macrocytic anaemia.

It's not uncommon to have both types at the same time. That means a mix of big cells and small cells - which, together, can give a normal value for the MCV. But another thing measured, the Red cell Distribution Width (RDW) will be high (greater than 14%) in that case.

Ask for a printout of all of your results and post them here.


Thank you for your response.

I was fairly sure they were not the same test but glad to have it confirmed. I have yet to meet the doctor as I have only just joined the surgery but I have spoken to him over the phone and did not like the way he cut me off from explaining my symptoms and why I wanted the B12 test.

I get very anxious with doctors so this does not bode well for our first meeting. I shall do as you suggest and ask for a printout. I'm hoping that it was just a misunderstanding on the part of the receptionist when she said the iron results were for the b12 and that I have been listened to and had the test done.


Managed to get a printout today. My B12 levels seem quite healthy I think. Which surprises me considering all my symptoms. I have been supplementing with methylcobalamin sublingual for over 8 months. Could this corrupt the results?

HbA 1c levl -IFCC - 32mmol

serum vit b12 347 ng

serum folate 7.4ug

serum ferritin 5 ug


Haemoglobin estimation 112g/l

platelet count 495


Haematocrit 0.365

MCV 73fl

MCH 22.4pg

MCHC 307 g/l

RBCDW 14.8%

Everything else seems to be well within range.

If someone could make some sense out of this lot for me I would be most grateful.


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