B12 was low and only after only two shots its now way too high?

I have been diagnosed with a rare disorder called Mastocytosis, it's a mast cell disorder. I have issues with gluten and wheat. I started losing a lot of weight and decided to see a few specialist regarding this. I had a colonoscopy done and they cultured the colon and found that I had too many mast cells in my lower intestines. I'm not sure how much of b12 relates to this but I was low, after one shot then, it was in normal range. A year later, I was feeling very ill and not myself. I stopped eating wheat and gluten and had less attacks. Which is in result to the mast cell disorder. I just a week ago had my blood work done and requested a b12 check. The normal range for b12 with this pathology is 245 to 840. I was 30. I was 30!!! 30? I'm shocked. So looking at the rest of the work up. My red cells are normal and along with everything else. The doctor has ruled out pernicious anemia. I took in the last week two b12 shots and started feeling worse. I got the results back and now it's 2000. Way over the normal limit. I'm experiencing tingling in my hands and am just not myself. Could someone tell me what other disorders or diseases can cause this? I'm obviously not absorbing b12 in the long run but why so high after only two shots. I'm worried.

2 Replies

  • 30!!! A couple of shots isn't going to sort you out, you need as an absolute minimum 6 loading injections over 2 weeks, then the standard is 3 monthly injections. However if you have neuro symptoms (i.e. tingling/numbness) then it's alternate day injections until no further improvement, followed by 2 monthly maintenance. This treatment is as per the BNF section 9.1.2 if you are in the UK.

    There is a list of symptoms here so you can see how many you have:


    May I ask how the doctor has ruled out PA? Because it doesn't matter if your blood cells are normal, not everyone gets haematological changes. Also you could have a coexisting iron anaemia which would normalise the FBC. Has he tested anti-intrinsic factor and anti-parietal cells? Also if he's run the antibody tests and they're negative it doesn't rule out PA, the tests are not completely reliable. These links might help:



    If you had 2 shots and then a blood test of course your levels will be extremely high, that's what happens straight after a shot. But it doesn't tell you anything about how much is getting through to the cells. Once on treatment they're not supposed to test serum B12 for this reason, it's irrelevant.

    Feeling worse after a shot is also common, start-up symptoms. You need to make sure your folate and ferritin levels are really good, not just in range. Get copies of all your results and see for yourself, most doctors will tell you they are normal when they are right at the bottom of the range.

    Here's a link to help you worry a bit less about levels, there is no known toxicity for B12:


  • Hi Christyander

    Firstly I assume you are not confusing Mastocytosis with Macrocytosis. Regarding the B12 aspect, I think Hampster 1 has given you all the good advice and a lot of excellent information to look into.

    Regarding the Mastocytosis you should look at the Mastocytosis Society of Canada for details, the link below should take you straight to their info page.


    Hope this helps and you soon find your way to feeling better. B12T.

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