low b12 levels with hypothyroidism - Pernicious Anaemi...

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low b12 levels with hypothyroidism



I posted in thyroid forums and my b12 and ferritin is quite low so I was suggested to post here as well

I am hypothyroid with possible hashimoto's

SERUM TSH : 3.402 ul Uu/ml

SERUM FT4: 1.12 ng/dl

SERUM FT3 : 2.50 pg.ml


FERRITIN : 14.4 ng/ml

VIT D is 31.8 ng/ml

to raise b12 will mecobalamin 500mcg daily and to raise vit d 800 iu daily be ok dose?

*my serum folic acid was 5ng/ml in jan 2017 when my b12 was 324

any help is much much appreciated

Thank you in advance

16 Replies

you really need to get a proper diagnosis of a B12 absorption problem and try to find out what the cause is - though most likely is PA assuming that you have B12 in your diet - ie you aren't a strict vegan.

Potential absorption problems would also include coeliacs and h pylori along with a whole raft of drug interactions.

The drop in your levels does seem to be significant and I really hope that you can work with your GP on getting a diagnosis. They may want to do the tests - particularly if you are in the UK. Would also be good to have a list of symptoms.


ferritin is a good indicator of iron levels and although it is in range there is a body of evidence pointing to people with thyroid problems needing slightly higher levels - around 40 at the bottom of the scale to be well. To confirm that you do have an iron problem it would be good to have a full blood count done - interpreting that if you are both iron and B12 problems and iron deficiency will tend to make blood cells smaller whilst folate and B12 lead to an anaemia in which the red blood cells are larger and rounder.

things to be aware of in speaking to your GP will be that serum B12 taken as a single indicator will miss 25% of people who are B12 deficient but pick up 5% who aren't so symptoms are an important indicator. whilst macrocytosis is a symptom of B12 deficiency it isn't a defining characteristic and 25% of people presenting with B12 deficiency don't have macrocytosis.

tests to help clarify B12 deficiency if results aren't giving a clear indication would be MMA and homocysteine - both will be raised if cells don't have enough B12 - but can also be raised by other things - including folate deficiency in the case of homocysteine.

The test for PA - IFA is prone to false negatives 40-60% of time depending on the assay method so a negative is a long way from proving that you don't have PA.

that is confusing! if i get folate done, shall it be enough ? I am not Vegan

the only symptoms bothering me are

weight gain


Bloated (swelled tummy like pregnancy)

memory loss which i thought was brain fog due to hypothyroid, I keep on forgetting things


muscular pain

Gambit62Administrator in reply to hypomomoffour

most of the symptoms you mention are more likely to be thyroid than B12.

the bloated feeling could point to low stomach acidity which would affect absorption of B12 and other minerals and vitamins from food.

I know there is a lot of chatter on the TUK forum around levels needing to be over 1000 but that is based on taking comments in one book that really relate to the situation for people who are being treated for B12 deficiency with injections totally out of context. Raising levels of B12 to high levels in the absence of an absorption problem can potentially lead to a functional B12 deficiency so isn't something I'd really recommend.

Have you discussed your results with your GP?

bernie51 in reply to Gambit62

Sorry to butt in Gambit62 but can you tell me what "functional B12 deficiency " is ? and what effect it would have on somebody ? Thank you.

Gambit62Administrator in reply to bernie51

functional B12 deficiency: high serum B12 but not enough available at the cell level

metabolising B12 involves absorbing it from your food, transporting it to cells in blood and then using it in your cells.

Absorption problems affect the first step, leading to low levels of B12 in blood.

Some people respond to high levels of B12 in blood by shutting down the mechanism that lets B12 get from blood and into cells - leading to high levels in blood but not enough getting through to cells - so cells are left B12 deficient ... all the same symptoms as a B12 deficiency caused by an absorption problem.

Whilst excess B12 is removed by kidneys the reaction that leads to a functional deficiency also seems to affect the efficiency of this process so can leave your cells deprived of the B12 they need for a long time after supplementation stops.

bernie51 in reply to Gambit62

Thank you for your helpfull explanation Gambit62 . So given the above how would functional B12 deficiency actually be diagnosed .?

Gambit62Administrator in reply to bernie51

a) symptoms

b) looking at indicators of what is happening with B12 at the cell level - eg raised MMA and/or homocysteine levels in the presence of high B12.

there are other things that can cause levels to be raised so testing would also need to rule out these (which includes folate deficiency in the case of homocysteine.

bernie51 in reply to Gambit62

Thank you again Gambit62 . Your knowledge base is amazing.

My brain fog thyroid brain has problems retaining alot of information....have to write things down in my little book. 🤔🤔

You'll see from the BMJ research document (link given below - bottom of page 3 re. Tests ), that MMA is the most representative test to ask for as homocysteine can be raised in thyroid disease.

will schedule an appointment in a day or two :) thanks for the feedback

Marz in reply to hypomomoffour

B12 Deficiency is very common when Hypo as digestion is slowed along with other processes involved in extracting B12 from the proteins ...


Seems Sally Pacholok and Dr Stuart are not alone in considering B12 test levels are set too low - Professor David Smith does too, especially for people over 60 years of age.

In any case, test results at any age cannot be taken in isolation - latest BMJ medical research advises that symptoms are paramount, especially when combined with autoimmune hypothyroidism - although many symptoms overlap (I note you are being given advice on TUK forum re. TSH levels etc), with your level of B12, your other deficiencies combined with fatigue, means possible malabsorption should be investigated - this link , (which you may already have seen on TUK ) posted by Dr John Midgley, scientist and advisor to TUK, shows why:


"The natural history of HT is the progressive reduction of thyroid function till overt hypothyroidism (24) with a rate of progression of 2–4% per year (23), while that of gastric atrophy features the progressive reduction, till disappearance, of parietal cells, leading to reduced or absent acid production (3, 22). These alterations interfere with absorption of essential nutrients leading, at first, to iron-deficient anemia, followed by PA if the self-injurious process involves the IFA".


Latest BMJ research document with useful summary:



As it is established in the research quoted above and BCSH guidelines, etc., that you are at greater risk of PA/B12 deficiency if you also have Hashimoto's or other autoimmune disease, it is is surely better to catch B12def. in the early stages than wait for further neurological symptoms to appear, and risk devastating permanent damage.


PS. From Sally Pacholok and Dr J Stuart's excellent book, " Could it be B12? - an Epidemic of Misdiagnoses":

"B12 deficiency can strike anyone at any age but some patients are at far greater risk than others. THe majority of cases of B12 deficiency stem from malabsorption disorders (see chapter 12), and seniors are at highest risk because 30 to 40 per cent of them have atrophic Gastritis. This condition(as well as chronic proton pump inhibitor use) drastically reduces levels of stomach acid needed to free B12 from animal proteins."


"At this time, we believe normal serum levels should be greater than 550 pg/ml. For brain and nervous system health and prevention of disease in older adults, serum B12 levels should be maintained near or above 1,000 pg/ml."

Marz in reply to Polaris

I have to say I found the book by Sally Pacholok an excellent read - especially for those of us who do not profess to be experts - by that I mean those who forget to post relevant links from time to time.

We all have to start somewhere with our knowledge and having the book - Could it Be B12 ? - on our shelf is an excellent place to start.

Thank you for your post Polaris ...

Polaris in reply to Marz

Absolutely Marz - I particularly liked the way the book reinforces and precise s the important parts of the text in bold in little boxes at the side of the page - great for those of us with foggy brains 🤗

Working on the frontline in emergency medicine dept. of a large city hospital, Sally (with PA) and her husband recognised many tragic cases of undiagnosed PA/B12 def.

Marz in reply to Polaris

One of those boxes you mention related to me - a Crohns sufferer and her story. Can you believe that when I had my Terminal Ileum removed in 1973 and had six monthly follow ups - no-one mentioned I would need B12 for life. Hence these books are of huge value. I learnt all about it on the Thyroid UK Forum where I have been a member for almost 6 years 😊

Polaris in reply to Marz

It's truly horrifying to imagine what would have happened to you Marz, if you hadn't joined HU and read up research on the complex issues that interconnect.......

I can't remember what my first introduction to B12 was but probably also through TUK forum. I do know Sally's book (and the video on B12def. website) was an early introduction. .

Looking back, I can see they both gave sound and comprehensive information on the varied issues that can be quite daunting to take in initially but it spurred me to delve further to get to the root of our family autoimmune problems.

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