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Pernicious Anaemia Society
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Is Active B12 rest a fasting test?

Hi all,

I’m struggling to understand why my two active B12 tests only a week apart are so different. The only difference was a)the time of day b) I fasted for the private one, but my GP told me not to fast for the nhs one.

Private 7am showed me as Active B12: 22.9

NHS 11.30am showed me as Active B12: 46

Any ideas please? Thank you

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Thanks Hidden

For the NHS one I don’t have a range, simply >30 pmol/L, the private was 25.10-165 pmol/L.

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Do you take biotin? It can effect b12, tsh and t4 lab test results, depending on the method the lab uses to test for them.

endo.confex.com/endo/2016en...

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Hi KimberinUS

No, I don't take anything currently, so I'm really surprised that there's this difference!?

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Sorry, i cant think of anything else that might cause such a variation in the lab results.

Due to the variation, i would ask for a third

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Thanks KimberinUS

That's exactly what I thought.

I've been through everything, the only differentials were the time of day and one I fasted for and one I didn't.

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Hi Hidden

I don't take ANY supplements at the moment?

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