Pernicious Anaemia Society
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Hi B12 post loading dose


Firstly I'd like to apologise for not replying to any posts I'm feel just to new to contribute as of yet.

I've just had the results of a B12 level post loading dose of 5 injections and it was 2000 original was 116. I haven't had IF results back yet. My question is, why is this considered to be abnormal and what happens next. Symptomatic ally I am only now seeing some of them resolve. If, as my GP indicated this is 'my diet' which is healthy, not vegetarian but with little red meat, how long will I retain this level of B12 before it drop again?

Thanks in anticipation

5 Replies

How long after your last injection did they take that b12 test? It usually drops quite a lot after the injections. I think 6 weeks after my loading injections I was 109. Actually you absorb b12 best through dairy such as eggs and milk, I found that red meat did little for my b13 levels. Also fish is good at raising b12 levels but to be honest dairy alone is quite effective.


It's been about 3 weeks since loading dose of 5 injections I've been eating eggs and yogurt (which I hate) in an effort to increase B12 intake but I suppose I will have to wait for the IF test results to know if I'll get any more injections seeing as level was so high

Thanks for reply


Its normal to have a high B12 reading after loading doses, that is the idea, to flood the body with B12. Then you go onto maintenance and then it is very different per person how much they hang on to the injected B12. No norm there! Marre.


I wouldn't bother with the eggs, particularly if you hate them as I believe there is actually something in either the white or the yolk that actually stops the B12 they contain being absorbed.

The amount of B12 you are given in a loading shot is nearly 1000x times the RDA for B12 ... and your level is probably above 2000 it is just that the scale for measuring becomes wildly inaccurate at that point so they don't bother to measure anything above that.

People vary very much in how quickly they loose B12 - study in the 1960s showed that on average people retain hydroxocobalamin twice as long as cyanocobalamin but also was quite clear that the deviation on the results was so great that you can't assume it lasts twice as long and in some of the group it only lasted for a much shorter time than cyano.

It does sound as if diet is unlikely to be the factor even though your GP considers that it is - red meat isn't the best source if they are basing their hypothesis on how much red meat you are eating because it isn't the most readily absorbed form - which is fish and dairy.

I had a B12 test done at Christmas and result was over 2000 ... but then it was a few hours after I'd taken 2.5mg of methyl as the doctor wanted to do it as part of a medical review - waste of time really ... I hadn't known at the time I took the nasal spray that she'd order the test ... though I'd expect mine to be high as I generally take around 3-4mg a day - which is what I need to keep myself functioning well.

My folate was also high because I supplement that to make sure my body has enough to use the B12. There isn't anything to worry about in having a high level - its non-toxic and there are no known downsides. Celebs use B12 infusions as a pick me up and there was a post recently about using it to stave off terminal cancer.

Know it is a bit scary - was surprised that my lab results all came back marked 'no action' and I didn't have to (im)patiently explain to medical staff that there isn't a problem with high levels of B12.

Hope that you get a positive on the IF though it's not a particularly reliable test and often needs to be repeated several times before it actually comes back positive - think the NICE guidelines cover that if you need to explain to your GP.


Thank you all for your replies this is all very confusing and a mine field to negotiate but the more I learn the better informed my GP consultations will become....I hope


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