Thyroid UK
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Active B12? any suggestions for private test?

I cant find the page about active B12, my b12 was 450, no range, not sure what it should be.

Bloody test are useless arnt they, i was tested for magnesium and was told normal lol when only 1percent it actually in the blood and the other Magnesium is in the cells.

this is such a epidemic. Whats the best b12 supplement to take for vitamin D, I am currently having Magnesium flakes in my bath, see if that helps.

have nice day xxxx

10 Replies

mean for b12 not for vit D lol trying to phone DS S. before I pay for MRI.


The Nutristasis Unit at St Thomas’ Hospital provides this test. It is slightly more expensive than a standard serum B12 test. To obtain this test you need to get a signed letter from your GP requesting the test and you must attend the phlebotomy department at St Thomas’ Hospital.

For more information on the Active B12 (holotranscobalamin) test at St Thomas’ Hospital please go to: or contact the Nutristasis Unit at or phone Denise Oblein on 020 7188 7188 ext 52471 or you can visit the Axis-Shield website:




Funnily enough, I've just been looking into this myself. This might help

Not sure yet whether there's a discount available through Thyroid UK for this test.


Thanks, ummm I do live along way from St Thomas hospitol, thanks anyway,

will look at home blood test.


Merissa xx


Have you tried asking your own GP about private blood testing, most GP's will do this. Also the "normal" range of B12 is 190 - 950 and the optimum result you should be aiming for is about 600.

Here's a link to Amazon for B12 which is what a lot of people on here, yself included, take. You disolve it under the tongue so should not get any absorbtion issues.

Moggie x



I think that merissa wants an ACTIVE B12 test - not the usual run-of-the-mill serum B12. I doubt many GPs have any special access to such tests yet? A few with strong connections to labs, or Guys St Thomas, might know more and be able to do so.

Active B12 seems to be rolling out now further afield, but not, so far, to every area.

According to one source, a reference range for Active B12 is:

Holo-TC has normal refence value concentrations 21- 120 pmol/l


We recommend 32 pmol/l as cutoff.

Between 21 and 32 pmol/l deficiency might be confirmed by MMA


(Can't remember who posted that link the other day - but thanks!)

We can fervently hope that, unlike serum B12 and so many other tests which vary by laboratory, the reference range and cut-off point for Active B12 might be universal? But I shall not be holding my breath.


p.s. If I were you I would go for the 1,000iu dose.

Moggie x


Hey Moggie, nice to hear from you, hows things going with you? yer I might as well order my own. Thanks hope its hits the south.




Hi Merissa,

I'm having a bit of a chaotic time of it at the moment - off T3 due to a heart arrythmia and four days in my heart palps have stopped (lets hope for good) as I am due an operation the beginning of next month, so am now back on T4 only BUT I dont feel to bad for it suprisingly enough.

At one point I was very low in VitD (12.5) which, as you may know, can cause exactly the same symptoms as thyroid and looking back now what I thought was brain fog due to thyroid looks as though it could have been caused by low VitD.

Also went wheat free about 6 weeks ago (which can help an awful lot with absorbtion) so all in all coming off of T3 wasn't as bad as I thought it would be (well not yet anyway but it is early days).

Hope all well with you, you seem to be making good ground and are getting yourself sorted but like you say its a mindfield and when one thing is out of the way another seems to bite you in the

Moggie x


keep us posted Moggie, about your op, really glad you to have been making progress, fingers crossed.

big huggs x


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