Pernicious Anaemia Society
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How to determine amount of injectable B12 ml's to take, when switching from oral to injections?

I've been taking 10,000-15,000 mcg oral methylB12 and 400 mcg methylfolate. I just received my Oxford BioSciences methylB12 injectable. My doctor said that even though my transcobablamin B12 binding capacity is deficient, that the protein needed to carry it into cells isn't being executed properly, this is ok because I am supplementing B12. I forgot to tell her that I'm taking daily 10,000-15,000 mcg methylB12, a hefty amount. I am hoping that switching to injectable B12 will help my symptoms. My B12 related bloods:

Transcobalamin B12 binding capacity = 780 (825 = (or was it 800)-2000) - Dec 2017

Serum B12 = >1500 = (180-914) - Dec 2017.

Previous Serum B12 was 637, July 2014, after 5 months 10,000 mcg.

MMA = <0.10 = (0.00 - 0.40) - Oct 2016

Folate = >22.3 = (>5.9) - Oct 2016

I gave myself a test dose of methylB12 injectable, 3000 mcg in the reconstitute (Oxford only sells dry methylB12 and as per instructions, I reconstituted it with sterile saline). I noticed that my nausea, dizziness and weakness subsided for awhile, which was very nice. Given my above numbers, what should my dosage and frequency be?

I do have one autoimmune disease. I don't have intestinal bacteria overgrowth (tested). I did have cryposporidium treated two weeks ago (tested). I have an ulcer from NSAIDS (biopsy). I have some sort of iron absorption problem. Ferritin is now increased to 54, but other iron values now indicate iron toxicity.

2 Replies

According to the N.I.C.E guidelines on the maintenance 1 mg doses of B12 if you have Pernicious Anaemia with neurological symptoms they should be every eight weeks and for B12 Deficiency without neurological symptoms every twelve weeks.

However this "one size fits all" guideline is not always appropriate for everyone and as you are self injecting you can determine your own frequency as many on here (including myself) do so.

N.I.C.E guidelines below. Click on the link, then on "Scenario: Management" and scroll down to "Treatment for B12 deficiency"

I am not a medically trained person but I've had P.A. (a form of B12 deficiency) for more than 45 years.

I wish you well



Shootingstars - there isn't any hard and fast rule.

It sounds like you probably have a genetic problem that is affecting your ability to process B12 - these are quite rare - high level supplements are one way of sorting this out and keeping your levels really high so enough gets through too your cells.

It may be that the injections mean that you need to take less B12 - and more of the B12 will be getting into your blood that way but your body will also remove B12 quicker if the levels are higher .... and the rate at which different people remove B12 also varies so significantly that there isn't really a generalisation that can be applied.

Hope the experiment goes well.


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