Thyroid UK
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I want to get tested for Pernicious Anaemia but take B12supplements

1000ug sublingual per day. How long or do I need to stop taking the B12?

My blood tests have come back for the second time with abnormals.

RBC 3.60 4.20-5.40 abnormal

MCV 96 77-99

PCV 0.359 0.370-0.470 abnormal

MCH 32.9 27.0-32.0 abnormal

B12 412 260-911

The Endo said, ‘odd shaped red blood cells, what’s that all about’? I thought he was the clever one!

Graves TT and TED 100/125mcg levo and not feeling great.


11 Replies

Firstly, I strongly recommend that you get an Active B12 test (not the standard serum B12 test) as this appears to be the new, improved standard.

When you order your test (Blue Horizon do that as their standard B12 test now), then ask whichever company you order through. I have seen some suggestion that the lab needs to be informed if you are taking B12 supplements - but the labs are the ones who know. Not us.

Odd shaped red blood cells are a possible issue. Perhaps the best known is sickle cell anaemia when they are not the usual dished, round shape but more like the blade of a sickle. Other variants are possible.




Have received my B12 results from Blue Horizon Medicals:

Active B12 >128 pmo1/L 25.1 - 165.0 and told results within normal limits

Underneath these results it says insufficient sample for dilution. Please note change in reference range/units due to change in methodology. ACTIVE B12 is a better indicator of vitamin B12 status than Total B12.

I am confused - do you think with these results I should supplement or not and if yes what strength.

Thank you


Hi Rod - just read this post with interest. Did Blue Horizon B12

test yesterday (part of Thyroid Plus 10 Test). It was Total B12,

not the Active.


Well the serum Total B12 was all we had until recently. Hopefully it will be unambiguous.


Thank you Rod, helpful as ever :-)


Your blood tests are abnormal and point to macrocytic anaemia (enlarged red blood cells), usually caused by B12 and/or folate deficiency. Has your Endo referred you to a haematologist? Has your folate been tested? With those results you should really be getting further testing on the NHS and a referral to a haematologist, probably the only reason your serum B12 is in range is because you have been supplementing.

As Rod said, the active B12 test is better. Other tests that can be done are MMA and homocysteine. You can get these at St Thomas' in London with a referral letter from your GP (but you still have to pay). If you phone them they can advise about when to stop supplementing:

My Endo arranged the MMA test for me, although I do see him privately. Your Endo or GP, if you ask them, might test you for intrinsic factor antibodies (if positive, diagnostic of PA, but only positive in about 50% of cases), and parietal cell antibodies (positive in about 90% of PA sufferers, but can be present in other conditions so not diagnostic of PA).

Some further info here:

I also have Graves and feel quite lucky that my Endo listened to me re B12, as my bloods didn't show any macrocytic anaemia - yours do!


Gosh thanks for the detailed insight, really helpful.

How did you feel that lead you to question your B12? How are you dealing/supplementing now? And how to you feel now?

I think I might attempt the GP into referring me to haematologist. The Endo did see the results but did not seem to know why. I am very much northern based, so London isn't really an option. I certainly would be prepared to pay for the test if need be.

Another day, another lesson :-)


My case is slightly different as I was actually treated for B12 deficiency in 2006, when my levels were only about 170. I was only ever given the loading dose of 6 injections over 2 weeks, told I was cured and was sent on my way. Unfortunately I was as ignorant as my GP and didn't question this.

Last year I was diagnosed with Graves disease and it was only through my research on this that I realised the link with low B12. In some ways I feel the Graves was masking my B12 symptoms, as it was only when I went slightly hypo and then euthyroid that I realised I was still ill with this. The other interesting thing is that I never had classic hyper symptoms anyway, they always felt more hypo to me. I actually put on loads of weight. I only found out I was hyper by sheer accident in a routine medical.

Anyway, I digress! My serum B12 was around the 300 mark and every doctor I questioned said I was fine, including my Endo, my GP, and an A&E doctor (when I felt so awful I actually went to hospital). My folate was off the bottom of the scale as well, but nobody was bothered about treating this.

I contacted the PA society, who were great and gave me lots of advice and courage. After a very bad encounter with my GP I asked my private Endo to run tests for me which he did. So that's how I found I had elevated MMA and strongly positive parietal cell antibodies. I didn't test positive for intrinsic factor. This is all fairly recent so I haven't been back to the Endo to discuss my results. He wrote to my GP and I went back for B12 shots (I saw a different doc at the surgery)! Despite everything, he wanted to just give me 1 injection and then nothing for 3 months. I waved the BNF guidelines at him and insisted on the loading dose. I'm on 3 monthly jabs now but I'm keeping a diary of symptoms and I'll go back if I feel I need a shot sooner (might not get it). I also take 5mg folic acid (on prescription), a B-complex (Jarrow's B-Right), fish oil, and a methyl B12 sublingual spray (Boost) twice a day. Am thinking of moving on to the Jarrows 5000mcg sublingual tablets.

It's early days but sorting this out has changed my life completely. I feel like a normal person again, not just a shell who barely had the strength to get out of bed in the morning, let alone look after my marriage and my kids.

If you're in the North you should check out and Dr Chandy, who knows, might be near you. And I'd definitely seek that referral to the Haemotologist and get your folate checked. Read up as much as you can, as it's harder for them to fob you off that way! I would recommend the books "Could It Be B12?" and "Pernicious Anaemia: The Forgotton Disease".

I have really mixed feelings about self supplementing without a proper diagnosis, as you end up never getting diagnosed because serum B12 goes up quickly even when you're still deficient at tissue level. However I recognise that for a lot of people it's their only option.

I hope this has been helpful and not just a boring monologue :-)


Boring monologue, far from it! Moving and helpful, yes. :-)

Sometimes when someone tells you something you feel an instant connection. I feel another part of the mystery being revealed.

This is exactly why this forum is priceless, you would hardly believe what people are going through or have been through and yet still have the courage and strength to try and heal themselves whilst helping others.

Some reading to done me thinks.

In the meantime, thank you again and I wish you well. (I may ask more questions)


Well, it could be due to your B12 levels, but the good reading on the active B12 test makes that fairly unlikely, doesn't it? (This doesn't mean you won't develop problems if you stop taking the supplement of course).

I think a haematologist to follow up on the "odd shaped red blood cells" sounds like a good idea. That can cause anaemia too, because the spleen removes the odd shaped cells, thinking they are malfunctioning, so there is increased red blood cell destruction.


I am pretty unclear on the whole subject and only been alerted to the fact that there seems to a relationship between thyroid and B12.

I certainly did feel better when I initially started taking the supplement.

Again very interest what you say about the 'odd shaped red blood cells'.

Isn't it amazing that people on here can offer possible reason/solutions, yet the Endo, Head of Department too, looked completely baffled!?

Like I said, more reading required.

Thanks so much for adding your knowledge, appreciate all the help.


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