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Pernicious Anaemia Society
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Still suffering from pernicious anemia symptoms

Hi, I am a 35 year old female that was diagnosed with pernicious anemia 2 years ago. I self inject 1 ml of cycancobalamin every two weeks. Recent labs show mcv of 100.6, mch of 34.7, serum b12 at 1100. My doctor said my high levels just prove my anemia and not to worry. However it was then that he increased my injections to twice a month. I still suffer from symptoms like diarrhea daily, weakness, fatigue, extremely cold, dizziness, tinnitus, twitching in eyelid, tingling and burning in extremities especially in face and fingers. He thinks my injections are wearing off half way through the month and that is why he increased them. My question is should I be worried about my levels? They have increased over the last two years and all other labs are normal. And I have to admit that I am feeling better with the added injections.

6 Replies

You can't overdose on B12, and there are no known downsides to having high levels

Even at 1100 your levels are still in normal range.

There is a correlation between B12 treatment and higher rates of cancer ... and bigger tumours developing - but that hasn't been established as a causal relationship and theory is that the cancer incidence arises from the B12D period before supplementation (as that is a known risk) and unfortunately B12 may mean that cancerous cells reproduce faster leading to the bigger tumours. However, you are definitely at a high risk if the B12D isn't treated effectively.

Good that you have a doctor who is prepared to consider more frequent injections.

Good that you feel better with the more frequent shots.

People do seem to vary a lot in how they respond to B12 and there hasn't been enough research to really understand what causes the differences - though we are all different and variation in responses to foods, drugs etc are just a fact of life that science hasn't got very far with.

Couple of things to consider

a) you might benefit more from a different form of B12, eg if you have the MTHFR gene your body will be struggling to convert cyano to the methylated firm that is used at the cellular level. ou might find you respond better to methyl cobalamin - but you might have problems getting hold of this if you are based in US.

b) there is a thing called 'functional deficiency' - happens when your body produces antibodies to the transportation mechanism that gets B12 to your cells when levels of B12 in your blood are high - basically you have high serum B12 but none of it is getting to the cells that need it so the cells are still struggling with B12D - one study - Denmark I think - identified 30% of those being treated for B12D as having this response. I haven't come across much in relation to how to treat people with absorption problems when this happened but there was a paper on someone who needed very frequent high doses to stay well - which is what I need - and my theory would be that what needs to happen is so much B12 floating around that the body can't produce enough anti-bodies to destroy it all ...


Thank you so much for your reply. Do you think the high mcv and mch are normal then considering I do have pernicious anemia even though my serum b12 levels are high. It would make sense that I am not building up stores of b12 and it is only in my blood. I used to supplement with methylcobalamin sublingual tables but I never noticed a difference and my mcv and mch just continue to increase.


I don't have anaemia so it isn't something I'm particularly up on - anaemia is a potential symptom of B12 not a defining characteristic - and quite a lot of people these days - because there is folate etc in breakfast cereals, bread etc, tend not to show obvious signs of anaemia but are stil B12 deficient.

Just found this link that might help a bit


Your serum levels are high because you are getting B12 shots - one shot is about 800x the normal RDA so not surprising that your levels are high.

It sounds like you could be suffering from 'functional deficiency', ie the fact that your serum levels are high mean your body is trying to shut down the transfer mechanism so little if any is actually getting to your cells - it's only when you are getting so much in that your body can't actually create enough antibodies to shut the mechanism down that you get a benefit - so more frequent shots is, I think, the way to go ... but I'm not a medic or a biochemist or anything like that. I'm just going from my own personal experience. I get most of my B12 from nasal sprays which is a method of delivery that seems to work well for me. Even on the days when I have a shot I will supplement because I notice the symptoms coming back within 24 hours.

I use a mixture of hydroxo (which is the form in the UK where I live) and methyl because they seem to work better with different groups of symptoms

- hydroxo good for the psychiatric (depression, anxiety ... and it is an awfully long time since my levels got low enough for psychosis to be a factor - but even that was getting worse when I was on the normal regime here of one shot every 2-3 months)

- methyl good for neurological such as having a decent level of feeling in my left foot and not getting shooting pains from nerves being touched by tendons.

I tend to get through something like 3-5mg a day so don't think that I am actually using all of that up ... even if I am quite active ... or even losing all of it through urine (which is what the body does with B12 it can't use/store as B12 is water soluble). It wasn't until I started using B12 at this level that I actually stopped continuing to slide - balance went from struggling to walk to being quite happy at the top of a ladder pruning a grape-vine in matter of a few weeks ... and a few months later I realised that the depression and anxiety that I had had for decades had gone.

You may find that hydroxo is better for you than cyano - or if you had injectivle methyl that might work better ... or a nasal spray ... than the sublinguals. People vary a lot in how they respond to different formats and even different delivery methods and all you can really do is try - at least B12 isn't toxic so there is room to experiment.

Another thing to look it is where your folate (B9) levels are, as body needs folate to absorb and use B12.

My real battle at the moment is in balancing my B9 and B6 so I don't get bad headaches/migraines. Seem to have it right at the moment though :)

Hope you find solutions that work for you soon.

PS: I had a blood serum test back in December .. and B12 was off the scale but fortunately the lab had marked it as 'no action' so I didn't get grief from nurse or doctor ... not that it would really matter as I effectively treat myself these days but go back for shots just to keep it on my record.

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Do you think it's possible to develop functional deficiency after starting treatment? I'm wondering if that's why Many of my symptoms disappeared after three weeks of treatment and then suddenly started to get worse again?


Yes, I'm sure its possible and think that is what happened to me. My mother is the same - needs ridiculous levels of B12 to be okay. However, my aunt and brother - neither of whom have been formally diagnosed and haven't had injections - both manage very well using a nasal spray delivering 500mcg

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That's really helpful. Honestly, I was so excited when my symptoms started to go and then after three weeks of injections they all started to come back again. Now I'm beginning to feel like I did before I started treatment. So I guess all I can do is increase the b12 and see what happens, but that would mean injecting daily. I hate injecting all the time and sub linguals do nothing for me. I think I'll try the nasal spray too. Do you ever get to feel normal?


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