Thyroid UK
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Suspected B12 deficiency...want to check thyroid too!


Just popping over from the Pernicious Anaemia/B12 forum on the advice of somebody there.

I've been going back and forth to the doctor's since March with a range of symptoms including:

-faintness/lightheadedness (it never goes!)


-weak/numb legs and left arm

-joint pain


I displayed macrocytosis and nucleated red blood cells in a FBC. The doctor ordered a B12/folate test. My levels were 243, and I was not treated for a B12 deficiency as I was within range. I was tested for various things (and am now waiting for an elusive neurologist appointment) including: vitamin D, iron, diabetes, thyroid function. I was misdiagnosed - a virus, labyrinthitis, menieres. Eventually I started to do my own research and realised that although within range, 243 is a very low B12 figure and that many people can be symptomatic at this level. I discussed this with the doctor, who agreed it was possible and was given just one B12 injection and then told me to supplement as I wasn't "very deficient". I have since sourced my own injections and am currently into my second week of self injecting daily. I know that recovering from neurological symptoms with B12 injections can take quite some time, but in the meantime I am trying to rule anything else out which might be causing my illness. I know that B12 deficiency symptoms can mirror thyroid problems so I was wondering if anybody would mind letting me know if they think this is worth investigating.

My serum TSH level was 1.59 mu/l.

I know this is within 'range' but is it worth looking further, can these tests ever be inaccurate, misleading?

I appreciate any help or comments!

3 Replies

Hi, unfortunately doctors don't really understand the thyroid. The fact that you have only had the tsh tested is proof of this. You need the t3 & t 4, as well as the thyroid anti bodies. GP's don't do them generally and the tsh doesn't show you how well your thyroid is functioning. Most of your t4 is converted to t3 which is the active hormone you need. Generally, most people won't feel well until their tsh is under 1 or even suppressed and their t3/4 at the top of the range or even above.

Many of us here have to resort to private tests. On the main site www.thyroid uk you will see a menu on the left about testing, on that section you will see private tests. Blue horizon medical do the tests you need. If you do get them post the results on here with the ranges and people will interpret them for you. B12 deficiency and hypothyroidism go hand in hand.

Good luck. :-)

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I asked the doctors to check my thyroid based on my symptoms - I didn't question the result but I'm starting to realise diagnosing might be more complicated than I first thought. The evidence points to a B12 deficiency but I think it's good to rule thyroid issues out. My sister has hyperthyroidism - I don't know if a family history increases your chances of also suffering with with thyroid imbalances.

I have ordered a thyroid test- thank you for the advice.


Very often thyroid runs in families by not necessarily identical. You could be under and someone over for instance. I know private tests can be expensive but from what you say I agree you should look into it. Improving your B12 levels may well improve your thyroid levels as you need such things to be good to help the conversation of T4 to T3. Lots of useful information though on the Thyroid UK site.

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