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Pernicious Anaemia Society
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Iron deficiency anaemia affecting B12?

I've heard about low iron levels directly affecting B12, can anyone shed any light on this? I was diagnosed Coeliac five years ago and PA two years ago. Since April this year I have also had iron deficieny anaemia due to heavy menstrual periods. I have hydroxocobalamin 1mg/1ml injections every three months and am due my next one in two weeks. The past month I have been experiencing dizziness, a feeling of ear pressure and tingling/numbness in my nose and cheeks which my GP suspects is sinus congestion, but I'm not sure. Could these symptoms be due to the B12 becoming lower than normal alot quicker due to the iron deficiency? Are they typical of needing the B12 shot sooner?

8 Replies

actually heavy periods can be a sign of iron deficient anaemia so may be a question of which came first - if you have multiple absorption problems - both coeliacs and PA can affect ability to absorb iron - then I suspect its more likely that you have the heavy periods because you were iron deficient.

If you have a source for low iron levels directly affecting B12 I'd be interested to hear it - in general iron and B12 are used quite differently in the body.

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Thank you so much for replying, that makes a lot of sense. I wasn't entirely sure of the connection between iron and B12 absorption, I just remembered hearing something and assumed it was low B12 affecting ability to absorb iron but maybe it is the other way round as you say.

Interestingly, my periods are far less heavy since my haemoglobin levels and ferritin have gone back up.


not surprised that the periods are less heavy - sounds like it was the iron anaemia that came first then


Uh oh, that had never crossed my mind, and certainly not the GP's. Surely I can't still be having iron absorption problems five years into being completely gluten free. A whole new road to go down. Again!!

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PA can also affect ability to absorb nutrients and minerals beyond B12 as it can result in lowered stomach acidity, ie may be more than coeliacs. Going gluten free should, you are correct, have resolved problems with absorption due to coeliacs.

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I don't know of any connection between PA/ B12 deficiency and sinus congestion but by a coincidence I have had a sinus condition and B12. I had a sinus mucocele (one of the sinus cavities blocks up completely and causes bones erosion and in my case double vision.) It was cleared up by an operation.


Hi Monty71,

"past month I have been experiencing dizziness, a feeling of ear pressure and tingling/numbness in my nose and cheeks "

" I have hydroxocobalamin 1mg/1ml injections every three months"

In UK, people with B12 deficiency/PA with neuro symptoms are supposed to have a loading injection every other day for as long as symptoms continue to get better then an injection every 2 months.

You mention an injection every 3 months. This is the standard treatment in UK for B12 deficiency without neuro symptoms.

Do you have any neuro symptoms eg tingling, pins and needles, balance issues, memory problems, tinnitus, word finding difficulties plus other possible neuro symptoms?

See lists of B12 deficiency symptoms below




UK B12 treatment info

1) BNF British National Formulary Chapter 9 Section 1.2



All UK GPs will have access to BNF.

2) BSH Cobalamin and Folate Guidelines


I'd recommend reading the whole document. treatment info is about a quarter through guidelines.

Flowchart from BSH Cobalamin and Folate Guidelines


PAS (Pernicious Anaemia Society)


PAS tel no +44 (0)1656 769 717 answerphone

If you have concerns over your treatment for PA, it may be worth joining PAS. They can offer support and info to members.

B12 books

"What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Martyn Hooper is the chair of PAS (Pernicious Anaemia Society). Book is up to date with UK B12 guidelines.

"Living with Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Has several case studies.

"Could it Be B12; An Epidemic of Misdiagnoses" by Sally Pacholok and JJ. Stuart (USA authors)

Very comprehensive book about B12 deficiency with lots of case studies.

Unhappy with treatment?

Link about writing letters to GP about B12 deficiency


Point 1 is about undertreatment of B12 deficiency with neuro symptoms.

B12 blogs

There may be stories relevant to you on Martyn Hooper's blog about PA and B12 issues.


There is also an interesting blog about B12 issue son "B12 Deficiency Info" website.


I am not medically trained just someone who has struggled to get a diagnosis.


The first place I had odd feelings was in my cheek. not really pain but very odd and I thought I had an infected tooth or something, then one day is was really numb feeling and I got worried and went to the hospital. they thought I was starting bells palsy but just a few days later I got tingling and numbness in my feet and hands. My condition went down hill from there and Drs dismissed me as needing counseling. By the time I found a Dr who believed me and discovered what my problem was, I had what seemed like 100s of symptoms and blood test showed "NO DETECTABLE B12" I know that pernicious anemia can cause low Iron, but I don't know if low iron has anything to do with low B12. When you have PA, your blood does not mature properly, the red cells are enlarged and oval, they do not carry oxygen or iron properly. Don't fool around and take B12 shots daily for a while, taper to 2 a week, then one a week then one a month and never stop. After you get your liver levels up you can take it once a month. Some doctors give a triple dose once every three months. But if you are not healing enough, you need more. Nerve damage takes a long time to heal but you should see improvement in a few weeks.


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