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Thyroid UK
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Seeking advice for my mother. Is there any link among Hashimoto thyroid, B12 deficiency and mutation of the gene JAK2?

My mother has had Hashimoto for over 15 years now and she also takes pills for to control cholesterol and high blood sugar. In the last 2 years, the blood tests show high white blood cell counts ( ranging form 15.000 - 18.000 ) and high heamatocrit (50 when the high end of the range for women is 45). Her B12 levels are 320. She has very low ferritin and low folate levels.

She had many blood tests and a bone marrow biopsy. They are saying that the abnormalities in the blood tests are due to a mutation of the gene JAK2 and they diagnosed it as a myelodysplastic syndrome. My mother has no other symptoms related to a myelodysplastic syndrome. The haematologist has ruled out the possibility of B12 deficiency but she has prescribed 3 monthly B12 shots. ( it doesn't make sense really but what can I say?). They have also prescribed one aspirin a day in order to avid blood clots.

Has anybody had a similar experience? My understanding is that B12 deficiency may affect the bone marrow and it can manifest itself as leukaemia. I have read about patients whose blood tests & bone marrow got normal after having treatment with B12 injections.

Thank you!

9 Replies

It is advisable for B12 to be towards the upper part of the range which is 1,000. Most doctors are happy for result to be anywhere in a range. The 1,000 is to try to avoid dementia/alzeimers and, myself, believe that many who have dementia may well be due too low a dose of B12.

The Pernicious Anaemia Society can also help with your question.

Does your mother take levothyroxine for her thyroid antibodies.


Yes, she does. Thank you for your reply.


I also have Hashimoto and you are right that the gps are happy with B12 being low... I have had low B12 since 2012 ( 190) and last year I started having neurological symptoms and my B12 level was 165 and the GP advised me to eat food high in B12 and let me go. It was a few months later when my symptoms kept deteriorating, I started looking into it and I realised that B12 was the root of my problems. Still, struggling to convince my gp - but to be fair to him, he did give me B12 for 6 weeks and that's why I can cope these days and he referred me to a neurologist and I hope things will get better soon. Now, I am also worrying for my mother. Thank you for your help.



healthunlocked.com/pasoc will be more helpful discussing B12 deficiency and folate.

labtestsonline.org/understa... will explain what a high haematocrit and high WBC evaluations mean.

Your mother can raise low ferritin by supplementing iron and low folate by supplementing folic acid or methylfolate.


Thank you. Yes, I have posted the same question on the PASOC site. They have told her that because her haematocrit is so high, she can't have any iron supplements or B12 shots ( but then she was prescribed 3monthly shots?)


Hello VickyB12

I would be very interested to know this too, also for my mum's sake. My mum was diagnosed about 15 years ago with essential thrombocythaemia (ET), a myeloproliferative disorder, which means she has high platelet levels. It is also related to the JAK2 gene and she has to take a cytotoxic drug and an aspirin daily to manage the risk of haemorrhage +/- ischaemia. There is also a risk that ET could develop into a form of leukaemia.

My mum has never been diagnosed with a thyroid disorder, but has had borderline TFTs and symptoms that could be thyroid related. Her mum had a thyroid disorder and I do too, so it wouldn't surprise me if she did too.

I haven't yet found a link between the two, but must admit it hasn't been high priority on my list of things to research, given my own health issues.

Would love to hear if you find out anything more...


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Hi Lousy170, Has your mum checked her B12 levels? I am trying to see if there is a link between b12 deficiency and myelodysplastic syndromes. Having a thyroid problem puts us at risk for B12 deficiency. Both my mum and I have Hashimoto. I have a few articles that may be of interest to you and I will post them tomorrow... I will let you know if I find out anything else. 💐


Thanks for replying VickyB12, sorry I've only just seen it! I don't think my mum has had her B12 levels checked. I've tried to encourage her but she's only slowly warming up to the idea of being tested for things. There's a strong thyroid link, her mum had hyper then had RAI and went hypo. And I obviously have Hashi's, so unless it's completely skipped a generation she may well have a thyroid problem. When she was tested she was in range though, although not optimal. I've had genetic testing and I've got mutations that show why I've developed it, seeing as I have half her genes she may well be genetically predisposed.

I'd love to see some articles when you have a moment to post them : )



Hello Lucy,

sorry it took me so long to post the links:












Not sure the articles I had in mind are listed above... perhaps they are on my iPad... sorry... my theory is that Hashimoto causes B12 deficiency, which then if untreated it can cause marrow abnormalities and Jak2 mutation. Of course, I am not a medical person. But I wish someone did some research to seek evidence on the links among B12 deficiency, Hashimoto and JAk2 gene.

If I find the articles I have in mind, I will post them here for you.

Best wishes,



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