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Pernicious Anaemia Society
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Is taking Biotin causing your B12 to show higher than it really is?

I saw these links in the thyroid forum and thought all b12 folks, those with just above deficiency range (and therefore cant get injections) and those with super high, possible functionally def. Would be interested.



4 Replies

Thanks KimberinUS

What the articles are saying is that supplementing with biotin (B7) affects the assay methods for tests for both B12 and thyroid function tests - it isn't affecting the levels just means that the test results come back elevated because the B7 interferes with the test method.

A timely warning to people to ensure that they tell their GPs if they are supplementing anything - and something to ask people about if they report high levels in the absence of B12 supplementation.


I dont think telling a doctor you are taking Biotin is going to give them one moments pause. I doubt if Doctors know which assay method is being used during lab testing. Why would they?

This is very important info for b12 and thyroid patients whose doctor only look at lab results and pooh pooh symptoms.


I agree that most doctors won't be aware of the link but if you point it out before the test is done then they can't come back to you and say 'why didn't you tell me so we didn't waste money on this test'.


I agree Kimber and thank you for posting.

My B12 was tested on two occasions as part of a whole range of blood tests. Each time I explained to both GP and nurse there was no point including serum B12 test as I'd been supplementing, it was completely ignored and, of course, came back over 2000.

Their unwillingness to listen influenced my decision not to waste more time banging head against brick walls but to self treat with injections.


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