Sudden drop in B12: Hi all. I have a long long... - Thyroid UK

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Sudden drop in B12


Hi all.

I have a long long history of iron deficient anemia - often quite severe but very responsive to standard iron tablets. I have been monitored closely for the past 2 years for TSH, B12 and haemaglobinopathies. My TSH is rising but has still been in range, free T3, T4 are bottom of range and my B12 has been normal throughout.

In November, my HB suddenly dropped to 85 but I was fairly symptom free. My ferritin was low so I started ferrous fumarate daily but, despite this, my most recent bloods show an HB of just 78 and a sudden significant drop in B12. I have to see my GP next week, she has repeated my thyroid function and doubtless I will need to supplement. Is it usual for B12 to suddenly tumble in this way? I am a vegetarian but eat large amounts of bread and dairy products. I feel pretty unwell as you can imagine, it's a different feeling from iron deficiency.

Thanks for reading. Clare

12 Replies

Maybe your doctor should check the 'intrinsic factor' of your B12 to eliminate pernicious anaemia..

Fennella02 in reply to shaws

Thank you Shaws. This has been checked in the past - 6 months ago. Could it have changed?

Thanks Again. Clare

What B12 are you supplementing and how ?

Fennella02 in reply to Marz

Hi Marz

I haven't been supplementing B12, I haven't needed to as my B12 level was normal. Suddenly it's not and I shall need to once I have seen my GP on Weds. Any suggestions?

Marz in reply to Fennella02

You really need to ask your GP as to why your B12 is not being absorbed and check for PA. I would also assume you are B12 deficient at all times and just keep supplementing. A normal result is not an OPTIMAL result. Normal is within the range of 180-900 - when it needs to be around a 1000 to prevent cognitive decline. B12 Deficiency can become a neurological condition if not diagnosed and treated.

You also need to be taking a GOOD B complex to keep all the B's in balance as Folate and B12 work together in the body - it is very complex.

How are you treating the iron anaemia ?

Fennella02 in reply to Marz

Many thanks Marz

It's interesting that I have had Neuro symptoms for the past couple of years which have baffled the medics which is why my thyroid, B12 and Vit D have been closely monitored. The neuro stuff has improved gradually which I assumed was due to the Mycophenolate for my UCTD taking effect. It is only now that the B12 is flagging. I have been concerned that perhaps the Myco was responsible for the B12 deficient anemia. I shall start supplementing straight away. Many thanks. Ckare

Marz in reply to Fennella02

...especially as you are vegetarian :-)

Clareb67, vegetarians and vegans need to supplement B12 because B12 is only available from meat, fish and eggs. If your B12 is deficient (below range) your GP should restore levels with injections and once restored you should maintain levels with sublingual lozenges, spray or patches. If B12 is low in range you probably won't qualify for injections and should supplement 5,000mcg methylcobalamin for a few months to raise levels and can probably reduce to 1,000mcg thereafter. Take a B Complex vitamin too to keep the other B vits balanced.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

Fennella02 in reply to Clutter

Thank you Clutter. Your advice is very helpful. Can I buy high dose 5000 mcg methycobalamin or do I need to take 5 x 1000 mcg (I have seen this dose online)?

Many thanks. Clare

Marz in reply to Fennella02

Jarrow do a 5000mcg on-line :-)

greygoose in reply to Marz

So do Solgar. :)

Marz in reply to greygoose

Am not a Solgar fan. The Organic Shop I used to visit in Cornwall wrote to all suppliers about GM ingredients. Solgar were the only ones that did not reply. So he stopped stocking their products. Silly I know - but funny how some things just stick. I expect there are GM ingredients in loads of supplements from the US - unless they state otherwise. Perhaps Solgar do now - haven't looked for years :-)

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