Could high oral B12 intake (1000-2000mcg/day) cause hyperthyroidism? I noticed from recent blood work that my serum B12 was lower than it used to be: currently at 344 pmol/L for a range between 150 to 600 pmol/L. It used to be 732 pmol/L in 2018. I was diagnosed with Chronic Fatigue Syndrome last March, and suffer from symptoms that might suggest I need a boost of B12: extreme exhaustion, depression, anxiety, constantly catching colds or even flus, and feeling of weakness in my legs. So, 4 days ago I began supplementing with B12 and I immediately felt like I had “just woken up after a very long nap”, like a magical switch after many years of progressive debilitating condition. Now, I understand that my initial reaction to B12 was possibly sychosomatic, as it takes a while for it to work. However, since starting the B12 5 days ago, I have started to suffer from symptoms of hyperthyroidism. Could B12 intake cause hyperthyroidism? Really feeling poorly and can’t even sleep.
High B12 intake causing my symptoms of hyperthy... - Thyroid UK
High B12 intake causing my symptoms of hyperthyroidism? Update: B12 not the cause of my symptoms.
If your B12 was within range, why take supplements?
Have you had a full vitamin check?
My Medichecks bloods last year indicated that I was deficient in Vitamin D so I’ve started supplements and feel much better. Without a test you won’t know what the problem is?
Hi Boon79. Thank you for your message. I suspect I have had symptoms of B12 deficiency for a while, but every time I see a doctor they say I am fine. I didn’t get the test for active B12 but only the serum B12 in my blood test and it’s not as reliable. I suffer extreme fatigue, get sick a lot and it takes weeks to recover, I am depressed and anxious as a result etc. I have had a lot of experiences where doctors didn’t listen to me, and so I avoid going unless I really have to. ( Like last month when I had a uti that lasted 1 month and took 4 rounds of antibiotics to go away...) Sorry for tmi. I was told I suffer from chronic fatigue syndrome last March but I am trying to find the reason why. I did check my vitamin D level a few months ago and it was actually good, at 83. My ferritin is too low though. I am thinking of seeing a doctor tomorrow. I will ask to check for folate, thyroid and iron.
greygoose SeasideSusie SlowDragon et al ..
Spotted Seahorse on the PAS Forum and suggested she posted here with her thyroid results for support. She is in Canada so possibly now asleep !
Low Ferritin could be responsible for fatigue
For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested.
Also EXTREMELY important to test vitamin D, folate, ferritin and B12
Low vitamin levels are extremely common, when hypothyroid, especially if you have autoimmune thyroid disease (Hashimoto's) diagnosed by raised Thyroid antibodies
Ask Doctor to test thyroid including thyroid antibodies and full iron panel testing for Anaemia
Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .
This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)
Link about thyroid blood tests
thyroiduk.org/tuk/testing/t...
Link about antibodies and Hashimoto's
thyroiduk.org.uk/tuk/about_...
thyroiduk.org.uk/tuk/about_...
List of hypothyroid symptoms
thyroiduk.org.uk/tuk/about_...
Thank you so much for your tips SlowDragon. Will get tested on an empty stomach. The clinic will open in a couple of hours.
What, exactly, do you call 'symptoms of hyperthyroidism'? We have to be very careful with symptoms, because so many of them can be symptoms of both hypo and hyper. They can also be symptoms of low B12 because thyroid symptoms are non-specific. However, I would think it highly unlikely that taking B12 could make you hyper if you were euthyroid before taking it. Have you ever had your thyroid tested?
OK, well, it would have helped if you'd mentioned that you've been diagnosed with Hashi's! In which case, you've doubtless had a Hashi's 'hyper' swing, and it's nothing to do with the B12. You should never have been put on anti-thyroid meds because that's not the right way to treat Hashi's. The high levels will eventually come down by themselves. The only excuse for giving anti-thyroid meds is if you tested positive for TRAB or TSI. Were either of these ever tested? Doctors tend to panic if they see a very low TSH, and all common sense flies out of the window!
Anyway, that's the past, we should be more concerned with the present and the future. You say you've been euthyroid for a while, but you should know that with Hashi's this can change in an instant. So, it's good that you're having labs done. But, be aware that just because the results are within range, it doesn't automatically mean they're good, as doctors tend to think. So, you must always get a print-out of the results and ranges and see for yourself. 
I agree with you completely.
My latest TSH result in early November was 1.41 mU/L for a range between 0.32 to 5.04 mU/L.
Unfortunately, Life labs automatically cancels the free T3 and free T4 if tsh is normal... This has been really frustrating not knowing my levels.
Last time I checked the Free T3 it was in 2017 and it was 12.1 pmol/L for range 10.6 to 19.7 pmol/L
I had the free T4 tested at that time too and it was 4.26 pmol/L for range 3.00 to 5.9 pmol/L.
The tsh at that time (2017) was 1.09 for range 0.32 to 5.04 mU/L.
I also recently my vitamin D levels a couple of months ago and it’s good: I m at 83.
Oh I don’t think I was tested for TRAB or TSI.
Last time I checked the Free T3 it was in 2017 and it was 12.1 pmol/L for range 10.6 to 19.7 pmol/L
I had the free T4 tested at that time too and it was 4.26 pmol/L for range 3.00 to 5.9 pmol/L.
Yes, I think you've got those two muddled up. No way could the FT3 range be 10.6 to 19.7. That's an FT4 range.
Anyway, your FT4 was quite low, although the FT3 and TSH weren't too bad. Certainly not hyperthyroid!
Oh my bad, I got mixed up with the free T3 and T4, thank you for noticing. My short nights are making me feel quite foggy ( only 3 hours of sleep last night.)
You still haven't told me what your 'hyper' symptoms are.
So, no TRAB or TSI testing, it's pretty unlikely that you do have Grave's, or that you are 'hyper' at the moment. But, your next tests should tell us more.
My symptoms are: constant elevated heart rate since Monday ( around 106 bears/minute last night) insomnia, unusual kind of anxiety, feeling warmer than usual and can’t handle heat well, some tremors that come and go, pressure in chest and pain ( now, I realize I should have gone to the doctor sooner), more “wired” than usual, much more frequent urination and bowel movements, pain inside the neck and back of neck plus upper back, bone pain in arms and neck, headache and flushed in the face, generalized weakness and feeling I have a fever too.
Hmmm… You sure you don't have some sort of bug? That sounds like a lot of symptoms! Still, as I said, your new results should give us a clue.
I am back from the doctor. I unfortunately felt quite rushed there (as usual) and met with a new doctor.
She agreed to re test B12 and thyroid panel but not the antibodies as she doesn’t think it’s necessary if my tsh is normal... I feel stupid, I was so tired I forgot to ask for the folate 😣.Feeling like I am stuck in that area, I will try to see a different doctor.
I told her I have been supplementing with B12 and explained my symptoms. She thinks I could have some kind of flu-like illness which would explain a lot of the symptoms.
I don’t think I mentioned it, but I suffer from depression and anxiety. I have been taking Wellbutrin for almost 4months without major issues, and started taking Buspar 3 weeks ago. It turns out I very likely have a strong reaction to it and the doctor advised me to discontinue this medication. Who knew an anti anxiety medication could cause much more anxiety?
I will keep you posted when I get the results. I also had an ECG.
Good news is that she doesn’t think B12 could cause my symptoms so I could be able to take it again.
I would post your results in a new post as they could be missed here ... 🤔
That’s a good point, I will do that 😊. I hope you have a lovely Friday and weekend.
Thank you - you too !
I think a lot of people on here knew that anti-anxiety medication could cause more anxiety. Especially if your anxiety is caused by being hypo.
She agreed to re test B12 and thyroid panel but not the antibodies as she doesn’t think it’s necessary if my tsh is normal...
Oh, honestly! They are so ignorant! They have no idea how Hashi's works. TSH has nothing to do with antibodies. But, I do agree with her about the flu-like illness.
I certainly feel unwell and have fever so there is definitely a possibiliry of having the flu ( even though I got the flu shot 3 weeks ago.)
I think a lot of people on here also know that having the flu shot is no guarantee that you won't get the flu! In fact, it could be that flu shot causing your present symptoms.
I knew it was still possible to catch the flu with the shot but was hoping it would not happen...Funny that you mention it, as my husband has blamed the flu shot too ( he didn’t get one this year and hasn’t been sick.)
So, all in all, I think we can rule out the B12 as the source of your problems.
Yes, I think so too ( and it’s a huge relief as I feel I need it.) I will try it again once I am not sick anymore.
I was on Cymbalta for my chronic pain and had horrible hyper symptoms ....hand shaking was crazy couldn't hold a cup of coffee without hand rattling... stopped it cold turkey (bad) and within 2 weeks shaking disappeared (I never took the stuff near my thyroid meds)
Wow that sounds like a horrible experience, I am sorry you went through this😣. For me it was Buspar, it caused the same symptoms you had. I will never take this stuff again.
Hi greygoose and SlowDragon, Thank you so much for your messages. I apologize, I didn’t realize I forgot to post my previous thyroid test results from 2009. Here are the results:
I moved from France to Canada in 2010. Upon my arrival, I developed weird symptoms that I attributed to anxiety and this for over 6 months. Eventually I met with a doctor in a walk-in clinic who took the time to look at my blood test results ( the ones then taken in Canada). He realized that I had been dealing with hyperthyroidism for those 6 months. I had lost a lot of weight then and my heart kept beating faster than I am used to. To answer your questions: I do have my blood test results that showed I have Hashimoto from 2009.
My TSH was then 5.76 mUI/L and the range was from 0.30 to 4.00 mUI/L.
My free T4 was at 11.4 pg/ml for a range between 8.9 to 17.6 pg/ml.
My free T3 was 3.7 pg/ml for a range between 2.0 to 4.4 pg/ml.
My anti-thyroglobulin antibodies were above range at 162.00 UI/ ml ( normal range is less than 115 UI/ml.
My anti- thyroperoxydase antibodies were at 10.16 UI/ml and normal range is less than 34.00 UI/ml.
Finally, my Thyroid Stimulating Hormone Receptor Antibody-was inferior at 1.00 UI and normal range was less than 1.5 UI/L.
When I moved to Canada, I wasn’t able to have directly access to my blood tests until 2014 unfortunately. Otherwise, I would have probably detected the hyperthyroidism sooner.
Thank you for reading.
SlowDragon and greygoose would not have seen your Reply as you forgot to put @ in front of their usernames and then they pop up and you can click onto them !!
OK, so you wouldn't appear to have Grave's. But, those labs don't confirm Hashi's, either. Were your antibodies ever tested before or after those results?
What would be more interesting would be the results where they 'diagnosed' you as hyper. Because in 2009 you were definitely hypo. And, you cannot go from hypo to hyper unless you have Hashi's. And, even then, it's not true hyper, it's just a Hashi's 'hyper' swing. Apparently, none of the doctors you've seen know how Hashi's works.
Yes, I really wish I could have access to those results of when I was hyper...
I saw an endocrinologist in France in 2009, and my antithyriglobulin antibodies were tested and appeared elevated, as well as my tsh. The antithyroglobulin antibodies were supposed to be less than 115 and mine were 162. The other antibodies weren’t elevated. The endo then told me I have Hashimoto’s and will need to take levothyroxine for the rest of my life.
I haven’t had my antibodies tested since then. I have had doctors refusing to do further testing because of the “normal” tsh.
Yes, most doctors are pretty ignorant, and do not understand the need for the correct testing.
Thing is with Tg antibodies, they can be elevated for several reasons - could be due to your low B12, for example. When you have Hashi's, they are usually a lot higher than that. So, I think that French doctors was somewhat premature in diagnosing Hashi's.
Your high TG antibodies results could be due to Pernicious Anaemia or Hashimoto's....or a mix of both
Here in the UK we have many Hashimoto's patients who only have high TG antibodies.
I don't know about Canada .......but here in UK the NHS refuses to diagnose Hashimoto's on only high TG antibodies
healthline.com/health/antit...
Hashimoto's frequently starts with a pseudo hyper type phase ....before becoming increasingly hypothyroid
Hello there , just to say I've hypothyroidism from hashimotos 27 years and along with that pernicious anaemia. NHS b12 injections aren't regular enough for my symptoms therefore I top up with b12 injections privately. But I want to say my thyroid hormone works faster and more effectively when my b12 is optimal. My b12 is usually always at 2000. I also take other important vitamins and minerals to support my thyroid hormone replacement or I do not benefit from my thyroid hormone replacement other wise. This is my experience. I've been on the low side before of low b12 and other vitamins and minerals that are supportive of Thyroid function and it was miserable mentally and physically and a long haul to get Thyroid hormone replacement to work. One can keep chopping and changing Thyroid meds when it's the underlying support of vitamins & minerals that's needed for any thyroxine or liothyronine or NDT to work. So I know from experience the importance of optimal b12 ect.
Hi Elizajoe, thank you for your message and for sharing your experience. I really do believe I need more B12 as I am definitely feeling miserable and get sick constantly and it takes weeks to recover... I must have had one “healthy week”only since September 1st. I am hoping I get more answers with my blood work today.
I understand how you're feeling. B12 is vital for life itself and can only do you good in many ways. I'm sure you've researched it's benefits. It continues to literally save my life
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