Thyroid UK
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Hi again, High serum folate levels - any ideas?

I am trying to get to the bottom of feeling so bad, all the symptoms of being hypothyroid but blood test levels all normal. However just had vitamins B12 vit D etc done and only one to come back out of range is serum folate which is;

serum folate 24.3 (4.6 - 18.7)

Please are there any thoughts on this? Have no idea what it means or what it indicates.



7 Replies

I have fairly low B12 300 ng/l [I'm over 60 and in Japan the minimum for my age group is 500] &.I take the Methylcolbamin version of B12.

My folate is >20 too, though this was ignored, and still is.

I read up on it online and found a reference to it indicating low utilisation of B12; ie:Folate is used up in the working of B12 when running right -so leftovers not so good showing low utilaisation.

Heavy supplementing can cause high folate level but not usually reccomended for men, mostly for pregnant women to assist foetus.

So high folate CAN be an indicator of B12 not quite 'on par' in the body.

B12 needs to be optimal for HypoT ,from all I read, so it is important to get your B12 result and raise the question if folate is still high.

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Tegz is right, what was your B12 level? Just because its in range doesn't mean it's "normal". I think Tegz is referring to the "methyl folate trap". I have a link to that here:

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Meant to say best to just post all your new results.

H x


Thanks for link- another less scholarly article is here

The only absolute reference to high serum folate quotes a level of >40 nmol/l -which is double the UK limit of 20. This was in the elderly in the US.

The outcome of this is unclear at present but the article relates higher growth in polyps etc with high folate and notes many times that anti folate therapy is used in cancer treatments.


My B12 is 177 ng/l and I am in my 50 's. I was told it is within normal range which it is not ! And folate 6.4 ug/l (3.1-19.9).

I have had another blood test results Monday. The practise nurse seemed not bothered but said she would get it rechecked as my tsh t3 t4 being done might as well eh? I said it was important for my breathing etc and that I was not absorbing enough b12 ? And ?

The medical profession leave a great deal to be desired when it comes to thyroid issues .

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That level of B12 is way too low, as is your folate. Your doctor should be treating you with B12 injections and a 5mg folic acid supplement, and testing you for Pernicious Anaemia (antibody tests for this are anti-intrinsic factor and anti-parietal cells). These are not conclusive though - you can test negative and still have PA.

You should really go here:

And here:



I know how that feels, as my tests came back "normal" although I felt hypo. GP did a lot of blood tests and my Vit B 12 was at the lower end of the scale, I then did some research, and found Vit B 12 is linked to t3/t4 metabolism, and accordingb to the forum, it should have nen 450-500! There's a very good book on Amazon called "B12 deficiency survival handbook" and one called " Could it be vitamin B12?" these might be of help in finding out if lack of Vit B 12 is affecting you too. Good luck!


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