Thyroid UK

Folate: Optimum Levels Advice?

Hi All,

We all know Folate should be at 'optimum' levels for Hypothyroid suffers, but my latest Folate blood test does not show an upper range just a minimum you should be above. Therefore I have no idea where I am in the range with no top limit shown :(

Any Folate experts know if this is a good or bad level? (Full results and Dr comments below). Many thanks

"Folate (serum) 8.3 ug/L (Range > 2.9)

Note new reference range effective 03/04/2017. If no change in dietary habits a normal serum folate makes folate deficiency unlikely"

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I really dislike this way of reporting folate level. It doesn't make any sense to me at all. I much prefer a range.


4.6 - 18.7 ug/L

3.9 - 26.8 ug/L

The above two ranges for folate are the ones I have in my records. I've seen people on the forum quoting other ranges for folate with the top figure being as high as 60, but I don't know what the units of measurement were.

I had both folate and vitamin B12 over the range at one point, on a Blue Horizon test. This was the doctor comment I got on the issue :

The Folate and Vitamin B12 levels are elevated. This is not a significant overdose of either vitamin, as both are well tolerated by humans even in very high concentrations. High levels are usually a result of supplementation or following a diet rich in the vitamins. Some advocate high doses of Vitamin B12 to combat the development of Alzheimer's disease.

One thing to bear in mind is that, since folate is water-soluble there is not a great risk of toxic symptoms because the body should lose excessive supplementation in urine.

BUT! There is a difference between folate and folic acid. I would never take folic acid to increase my folate level under any circumstances. Instead I would always take methylfolate. See these links :


Thank you humanbean ... Very good advice/info there :)

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this is what the BCSH guidelines (British Council for Standards in Haematology) say about serum folate test

Serum folate

The serum folate concentration reflects recent folate status and intake. Most clinical laboratories today measure serum folate by competitive folate binding protein (FBP) assays using chemiluminescence or fluorescence detection systems. Despite considerable variation in performance between assays, using the isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) international reference methods, there was close correlation of the consensus mean in the UK NEQAS surveys (Blackmore et al, 2011). This offers the prospect of harmonization of reference ranges for serum folate assays.

There is no clear consensus on the level of serum folate that indicates deficiency. Conventionally, clinicians have used serum folate lower than 7 nmol/l (3 μg/l) as a guideline because the risk of megaloblastic anaemia greatly increases below this level. However, there is a sizeable ‘indeterminate zone’ [between approximately 7 and 10 nmol/l (3 and 4·5 μg/l)]. Therefore, a low serum folate level should be taken as suggestive of deficiency rather than as a highly sensitive diagnostic test.

So, your result is in the range where a folate deficiency is unlikely.

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Many thanks Gambit62 , I feel reassured my Folate is ok, along with Vit D, B12, and Iron.... the important ones for us Hypothyroid lot :D

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