Low serum B12 level but top of the range Active B12 level.

[lucylocks]

Hi

I have popped over from the thyroid forum and hope someone can help with my results.

November 2017 my serum B12 level was 677 range 115 - 1000

In March 2018 it had dropped to 385 same range. I supplement 2500mg. B12. daily.

My Active B12 test with Medichecks in April was 153.000 pmol/L range 25.10 - 165.00

I am trying to understand the drop from 677 to 385 when I was taking the same amount of supplement and wondered if the reason could be,

1) I went gluten free for a couple of months in September and October last year but went back to eating gluten three weeks before the blood test ( could the omission of gluten helped me absorbed the B12 better)

2) I was not taking my supplement ten days before the March test as I had ran out and was waiting for my order to arrive.

The other thing I am confused about is that in March my result was low at 385 but the Active test was top of range.

Any advice would be gratefully received.

Thank you.

[fbirder]

The serum test is notoriously inaccurate and imprecise, so I wouldn’t worry too much about varying results. The important thing is that both results are well above average.

Your active B12 also shows that your levels are well above average.

[lucylocks in reply to fbirder]

Thank you for your reply.

I thought the 385 was lowish, as on the thyroid forum they say it is best to be near top of the range.

[Gambit62 Administrator in reply to lucylocks]

lucylocks, I've never seen anyone come out with a proper justification for that assertion. As Fbirder says most will be perfectly okay at 385. Hashi's brings a much higher risk of developing PA but that won't be resolved by taking B12. It may be that some processes using B12 run differently in the absence of reduced thyroid hormone levels but that would only be an issue if thyroid replacement therapy wasn't being done properly (admittedly quite common) or if there was some issue with using artificial hormone v natur al hormone (and I don't know if there has been any systematic research on that).

If you have been treated with B12 injections that introduces a factor which means that the normal range doesn't necessarily apply and people on injections seem to need much higher levels of B12... and I suspect that is the source .

If you aren't symptomatic of B12 deficiency - in the absence of the possibility of being undermedicated for thyroid - then it is very unlikely you are deficient.

[lucylocks in reply to Gambit62]

Many thanks for your reply,

what I do not understand is how the serum level is "lowish" in range but the Active shows high in range. I would have thought the Active would have been lowish also.

[fbirder in reply to lucylocks]

The serum test isn’t accurate. The active test is a lot more accurate.

It’s like measuring the pressure in your car tyres. The serum test is like kicking the tyres and guessing the pressure. The active test is like using a pressure gauge.

[fbirder in reply to lucylocks]

Yes, unfortunately a lot of people on the thyroid forum keep regurgitating the nonsensical idea that everybody should have B12 levels above 500.

If that were true then we would have to give everybody B12 injections, because 95% of the normal population have levels below 500.

As we often say in this forum, serum levels are untrustworthy. People with levels above 500 can suffer from a deficiency. But they have interpreted that to mean that everybody should be above 500. All they do is cause unnecessary worry.

[lucylocks in reply to fbirder]

I think they mean it has to be above 500 for thyroid meds. to work.

Do you think I should stop supplementing as my Active is near top of range.

Thank you.

[Gambit62 Administrator in reply to lucylocks]

lucylocks - I've never seen anyone come out with anything that really explains to me why B12 is needed to make thyroid meds work. It may help in some people but that is very different from saying it is needed for eberyone. I haven't been able to find anything conclusive either when I've researched on pubmeds.

If you aren't symptomatic of B12 deficiency then at best supplementing with high levels of B12 is a waste of money. If you were feeling bad before you started supplementing and it has helped I'd continue - it isn't toxic. But raising levels really high can cause problems in some people so if it isn't making a difference to how you feel I would stop.

Did you check that the units and ranges for both sets of serum B12 tests were the same? There are two units than can be used to measure serum B12 and one will give much lower levels than the other so the results may not be as different as you think if the units were different.

[lucylocks in reply to Gambit62]

Thank you,

both serum tests were done by the NHS but I will double check the units.

It is difficult to determine which symptoms are cause by thyroid or B12 as a lot of the symptoms overlap.

I stopped my supplement of B12 a three years ago to have the Active B12 test and I did suffer with a lot of pricking, tingling sensations. I think the result was around 65 then, so definitely lower than the recent test.

I think I will continue to supplement, but at a reduced dose.

Thank you for all your advice.