What is the conversion for red blood cell folate from nmol/L to micro g/L?

[Carrie234]

I'm researching folate and I'm interested to know what blood levels of folate are required to prevent neural tube defects in studies.

I found this study that states "red-blood-cell folate levels between 1050 and 1340 nmol/L, optimal for reduction of the neural tube defect risk".

pubmed.ncbi.nlm.nih.gov/297...

But I can't work out what that would be in terms of the NHS range of 3-25 micro g/L.

Can anyone help?

Thanks very much.

[JHEW0836]

I believe you are talking about 2 different blood tests for folate. One is the RBC folate test and the other is folic acid. I think RBC folate is a measure of how much folate is in your red blood cells. Folic acid measures how much folate is in your serum blood.

[Carrie234 in reply to JHEW0836]

Thank you, I did wonder about that. The NHS test is for serum folate. Folic acid is the name of the synthetic form of B9.

[FlipperTD]

Hi Carrie. Rather than digging back into my distant memory, here's what the University of Rochester publishes for Red Cell Folate. Folate has a molecular weight of 441.4 and they quote

"For red blood cells, a normal result ranges from 140 to 628 ng/mL or 317 to 1,422 nmol/L."

I hope this helps you. I would be cautious about accepting their 'normal range' however, as it's method-dependent.

[Carrie234 in reply to FlipperTD]

Great thank you FlipperTD.

So it's the equivalent of 463 - 591 micro g /L, but is measuring red blood cell folate so not comparable to the NHS serum folate test.

And also that the values they give are from 66% to 93% through the ranges from the University of Rochester, which is interesting.

As you say, I should be cautious about comparing percentage through range for red blood cell folate vs. serum folate, due to the methods they use to determine their ranges.

[Edit to my original post - the NHS range changed from 14/11/22 and is now 3 – 20 ug/L].

[FlipperTD in reply to Carrie234]

It gets more complicated! Red Cell Folate [RCF] is where the majority of the folate in the blood is found. To measure RCF We start by diluting and haemolysing the red cells, and then it's measured like serum folate. There's far more folate in red cells than serum, and many labs probably don't encourage RCF testing as it adds a few more steps to the process. Any range you find is [or should be] calculated by the lab testing the samples. But you can't compare red cell and serum folates. Serum folate is more transient.

[Carrie234 in reply to FlipperTD]

Thanks, interesting! Although I can't compare the absolute numbers, I was thinking I could at least very roughly compare the percentage through range for red cell vs serum folate. So if 66% to 93% through range was recommended for red blood cell folate, I would roughly compare to 66% to 93% through range for serum folate (i.e. 14 - 19 micro g / L for NHS serum range 3-20). I guess I was assuming the range is based on what is considered healthy in the sample of humans they used, which would hopefully be comparable enough across the 2 samples of humans used for red cell vs serum. However there are many ranges even for each method and each lab should provide the ranges it uses it seems, and I would really need the range they used in the actual study and even then there are too many variables. Hm! Ah well.

[FlipperTD in reply to Carrie234]

Yes, it is aimed at keeping us all guessing!

Bear in mind that serum folate is transient; it goes up and down with intake. Red Cell Folate doesn't do that as much. But be careful you're not comparing apples and oranges.

Happy Comparing!

[Carrie234 in reply to FlipperTD]

Very important thank you!

[SunflowerDreamer86]

I think the optimal for red cell folate is the upper third... the range can go from 600-3500! Do you know what was your range with the blood test?

[Carrie234 in reply to SunflowerDreamer86]

Thank you SunflowerDreamer86. Ah so the possible ranges for red blood cell folate you give there are quite different to the University of Rochester one. I was just wondering about this in theory as it is informative to know a % through range that has been studied and shown to prevent an actual problem (through correlation studies of course though).

[bookish in reply to Carrie234]

What about people with high serum folate due to folate trap and low B12. And increased risk of NTDs due to combinations of expressed polymorphisms, and need for methyl groups. Interesting thing to study though. Cheers

[Carrie234 in reply to bookish]

Yes I agree bookish, my thoughts too! People with high serum folate might not be using the folate. I really hope that the scientists studying neural tube defects took all of this into account, and studied the fact that some people get very ill in response to folic acid or folate supplementation. I don't think they did though. They could also do very useful research into why some people have high serum folate but cannot use it, and why some cannot supplement and therefore if there are cofactors (not just b12 and Bs) required or other health systems in the body are not working properly.

[bookish in reply to Carrie234]

Couldn't agree more! Methylfolate made a huge difference to me and my high serum folate went down when I started it. I have some related polymorphisms, low B12 (cellular) and a minor NTD. Folate cycle/methionine/one carbon metabolism are intricate and complex. Best wishes

[Carrie234]

It would be good if I could access the full study as I hope they would give the ranges they are using there, but unfortunately I can only access the abstract at:

pubmed.ncbi.nlm.nih.gov/297...

[Technoid in reply to Carrie234]

sci-hub.st/https://www.scie...

[Carrie234 in reply to Technoid]

thanks Technoid!