Do u have to stop Vitamin B12 before lab testing?

[Quest2019]

Do you have to stop Vit B12 before lab testing? Also how long before?

[Lalatoot]

Yes at least 7 days. It is because the biotin affects the way some labs test and skews results.

[SeasideSusie Remembering in reply to Lalatoot]

Lalatoot

B12 is B12. A B12 supplement only contains B12.

Biotin is B7, it can be a standalone supplement and it is found in a B Complex.

[Lalatoot in reply to SeasideSusie]

Thanks for clarifying that for me seaside Susie. I rely on your responses re vitamins usually.

[Quest2019 in reply to SeasideSusie]

Ok. Great. Thank you. I am only taking B12 at moment.

[BadHare]

Both my tests, including the second active B12 (?) that went off to London were negative. I read afterwards, possibly on the PA forum that one needs to stop suplementing for 3 months for accuracy. I'm having a bad few weeks soapologies as I can't remember exactly why. My GP was a twit & didn't warn me or seem to understand the impications or adhere to the NICE guidelines so I fixed myself with sublingual methylcobalamin. I now inject hydroxocobalamin weekly as it's cheaper than the expensive sublinguals that worked most effectively. I've even lowered my thyroid hormone intake.

[SeasideSusie Remembering]

Quest2019

It depends on why you are measuring your B12 level.

If you want a baseline then you leave off a B12 supplement for 4-5 months.#

If you want to know if your B12 supplement is an appropriate dose to maintain (or improve) your level, then you don't leave it off for any length of time before a test.

If you are actually talking about the B vitamin that is advised to be left off for 7 days before any blood test, then that is B7 - biotin.