Is 800 too high for vitamin B12?

[BishopBrennansArseHole]

Last time I had it tested (around 3 years ago) it was 400ish.
I’ve only been taking a multivitamin for about 3 weeks so not sure if that’s affected it.
But is this level something to worry about?

For our lab normal is 150 - 950 so 400 is fine and you would be ok to take supplements.

Although if you wanted it tested it would be better to do without supplementing so you don’t skew the results.

Ah, thank you for your reply. I did wonder if I should’ve avoided taking the vitamins but I kept having dizzy spells and was a bit panicked about it. So there’s a good chance it’s just the multivitamin that’s bumped it up?

There's no upper limit for B12 while supplementing, but taking oral supplements can hide a deficiency that is caused by malabsorption

But would a multivitamin really raise it that much in just 3 weeks?

Yes, because it's just testing the amount of B12 in your blood, not how much you are absorbing. So levels can rise quickly. Plus your level of 400 was years ago, you don't know what your level was 3 weeks ago just before starting the supplements... it may have risen slowly over the past few years. The more important thing is have your symptoms gone away?

Honestly, the only time anyone needs to be concerned about high B12 levels is if they are not supplementing (inc fortified foods, energy drinks etc) and B12 is naturally higher than the lab range

Thank you, that’s really helpful.
I wish I hadn’t started the multivitamin now tbh but I began taking them before I was even sent for a blood test as I was convinced I was lacking something. But now I don’t know if that’s what was causing my symptoms.
I’ve just checked the pack and it says it contains 20 µg of vitamin b12, I don’t know if that’s a lot.

Symptoms are ongoing but not as severe

That's 800% of the NRV, so aye quit a bit. Editing just to add that, being high dose doesn't matter. You're body will get rid of the wastage itself so it won't do any harm.