serum b12 in the norm and active high.

[Caroline1111]

hey everyone, I’m new here and hoping you can help me. Whenever I get my active b12 checked via Thriva they come back saying I am at the max they test at 150.

however when I get my serum b12 checked im within the norm. Last checked in Feb and I was 354 (150-1000) mmol/L range.

I know serum is your total (active and inactive b12)

So my question is…how can my active b12 be high if my serum is not? Is it possible that I could still be deficient with a high active b12?

it’s a mine field out there and this seems to be a super informative group.

my vit d and folate are low, I’ve struggled to tolerate supplements for some reason for the past year (folate) and few years vit d. I am typically anaemic in iron but take ferrous fumerate twice daily.

Any advice appreciated around the b12.

Thank you in advance, Caroline x

[Nackapan]

You don't mention symptoms. Yoh can be'In range ' as you clearly are but coukd have s functional b12 deficiency.

Do you eat a mixed diet?

Have you other things ruled out?

[FlipperTD]

Hi Caroline. I'm a [retired] scientist, not a medic.

It's difficult to comment on a fingerprick active B12 from a private laboratory compared to a Serum B12 from a different laboratory, but if the Active B12 is as you state, then you're not B12 deficient.

I am more concerned by the fact that you state you're typically anaemic in iron and take iron supplements twice a day. Is this being monitored? It is very easy to overdo iron replacement and that can have some dreadful consequences.

Sorry I can't be of more help.

[am111]

It is possible that you are using less B12 due to iron deficiency and hence your active B12 is fine although your serum levels (and B12 stores are on the lower side). If you are too concerned, you may take a shot every month or every few months to be on the safe side, although it may not really be needed.