I read this helpful info on a forum post here from the admin:
“Taking supplements that contain B12 will affect any tests ordered by your doctor to assess your B12 status. You should not take any supplement with B12 before having your B12 assessed (including MMA/homocysteine/Active B12). For testing intrinsic factor antibodies: keep one week between an injection and the test. ”
How long should I discontinue supplements for before going for testing?
I dont know of any reference that indicates exactly how much serum B12 is generally affected by supplementation. Certainly the amount is likely variable where intrinsic factor is working versus conditions of PA. Serum numbers can also rise without necessarily being fully effective to reduce symptoms.
If you've been taking high dosage (1000mcg+ B12) supplements daily for some time, its likely your B12 will be elevated. It can take a very long time for serum numbers to come down but I dont have any precise numbers on that I'm afraid.If anyone else knows of any research on this, I'd love to find it!
Which type of supplement have you taken? Its usually accepted that someone needs around 4-6 months to normalise levels.
I think its more about getting an accurate test result.
Levels can remain high ax yoh say for many months but probably not high enough to keep symptoms at bay.
The new Elisa test ( well 10 yrsts old shoukd?)should not be affected as was the older test equipment used.
It was on s post a few years ago.
So a week or two off b12 should suffice.
Of course testing shoukd be done prior to b12 treatment but not always done .
Thank you. My borderline low result came before I started the oral supplement, so I know that wasn’t affected. I started taking the oral supplement off my own bat, not realising that this needs further testing.
I am not very well at the moment (something different) and am ashamed to say that I got annoyed with my specialist for pestering me for blood tests. Now after reading the info feom the PA Society and here I’ve realised I am lucky to have a specialist who is taking this seriously.
I do have some auto-immune history in the family.
It was 1000 micrograms, one per day, for about a week. I slightly foolishly started taking them off my own bat after the doctor mentioned my levels were borderline low, not realising it might affect testing. I have stopped now.
The next test I am having is homocysteine.
My specialist may want to follow up with more testing – at the moment I am struggling to leave the house (different problem).
Neither of us thinks my illness is related to B12 but he wants to investigate any low or abnormal results just in case and then get levels back up so that there’s nothing making me worse at least.
At least 2 weeks. But the longer the better. Funny how they admit that B12 can be out of your system in two weeks and then you can have a test, but they only want to give us one injection a month or one every 3 months depending on what country you live in. Sorry just making a point. But they say about 2 weeks so that the B12 is out of your system. but I would go as long as you could possibly go to make sure that there is no B12 in your system.
I was told (by a doctor at the private anaemia clinic in Cambridge) that any supplements containing any B vitamins should be avoided for a month before testing, otherwise it may mask a deficiency.
Thanks Dilly_blue , Wwwdot and EllaNore . I will hold off for 4 weeks just to be sure.
I would also like to extend my best wishes to everyone struggling with getting diagnosis and treatment for PA and other B12 problems and my thanks to everyone who posts here and helps people. My main medical condition, orthostatic intolerance casued by autonomic dysfunction (similar to POTS), is also woefully underdiagnosed and misunderstood by the medical profession. I spend a bit of time on various groups trying to help people who may have autonomic disorders.
When I win lotto (!), I hope I get enough to do something for a few of us “misfit” conditions that can be diagnosed and treated by modern medicine but aren’t simply because of lack of education.
YIKES! Have I been kidding myself? One of the reasons I started injections was because my MMA and homocysteine were dangerously high. I have written several times, that since I began injections (after just two) my MMA and homocysteine started going down and 1.5 years later both are in range. BUT...I had not stopped injecting? Are these test results mis-leading? My serum B12, of course, has been high but I have not given that any weight. I THOUGHT (and inquired several times here) was that if my MMA and homeocysteine went down, it was because the injections are helping the B12 get into my cells and not just circulate around. Symptomatically, I have a long ways to go, but I thought I could relax about the MMA/homocysteine part. Any thoughts anyone? (I simply cannot go more than 2-3 weeks without an injection in order to get a more accurate picture but several docs agreed my previously very high levels were strong predictors of heart attack/stroke.
I suspect the doctor that I mentioned in my post above, was meaning over-the-counter vitamin tablets that could bring serum B12 levels up into just about ‘normal’ looking levels, despite there still being symptoms of B12 deficiency, eg pins and needles etc. I’ve seen it mentioned a lot of times in posts by forum members that while oral supplements can start to increase serum B12 levels they will not be enough to start to repair damage caused by B12 deficiency. And will result in the GP thinking there is no deficiency…
Intrinsic antibody test after B12 multivits
How long after stopping B12 supplements can I have a blood test?
B12 tested whilst on injections 
What to do before a uMMA test?
Blood Test results - Please Advise...
