Pernicious Anaemia Society
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Will homocysteine blood test be accurate after stopping B12 supplements for only a week?

Hi Everyone!

I'm new to the group. I'm in the midst of trying to convince my doctor that I have a B12 deficiency. My B12 blood serum level was in the "normal" range in 2014 and 2016. My peripheral neuropathy has improved greatly since taking subligual B12 for 45 days, averaging 12,000 mcg/day. I'm convinced that I'm B12 deficient. My doctor told me to stop taking B12 supplements for a week, then go in for a B12 blood serum test. I asked that a homocysteine blood test and a MMA urine test be added. She added just the homocysteine test.

My question: Does there need to be a longer period of time without taking B12 before taking the homocysteine blood test?

Any help would be appreciated.

Thank you

4 Replies
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all of the tests you mention are likely to be affected by the supplementation. Its usually suggested that you should refrain from supplementing for at least 3 months before having these tests.

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Thanks Gambit62 for the information. Stopping b12 supplements for 3 months would be difficult. I've only stopped for 2 days and the electrical shocks on top of my toes have already come back. I thought I read somewhere that the MMA test is used to check progress during treatment?

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MMA is a secondary marker of what is happening at the cell level. It will be raised if cell doesn't have enough B12 to recycle it but there is some debate as to whether it will always pick up a functional B12 deficiency - high serum but none available in cells. It is a marker on only one of the processes going on in cells and it is possible that cells could prioritise processes in different ways if B12 is in short supply. In general MMA is very responsive to treatment so tends to drop quite quickly if serum levels are adequate

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Thank you Gambit62!

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