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Pernicious Anaemia Society
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B12 testing

Hi, I'm new here and seriously ill and bed bound with nerve damage and fed Parenteral nutrition through a central line. I've recently had a total serum b12 test come back at 122 which i understand is defiecient but I've been told that the active b12 and mma homocysteine tests etc are more reliable tests? I am extremely worried about my health which has been diagnosed as a central nervous system failure but I'm starting to wonder how much is down to deficiency. My doctor has only started me on the loading dose of hydroxocobalamkn but not at the correct dosages from what I've read. I was thinking of getting an active b12 test privately but didn't know if it would be reliable after starting loading doseshis week? Can anyone advise? Many thanks in advance

13 Replies

I wouldn't bother with the active B12 test - given that you already have a diagnosis of B12 absorption problems and are being treated with B12 shots. It is going to be skewed by the shots.

Both serum B12 and active B12 measure the amounts of B12 in your blood - which is one step in metabolising B12 - it needs to get from your blood to your cells and then to be used in your cells.

Serum B12 can be useful if looking for an absorption problem but other things can go wrong with other steps - getting B12 from your blood to your cell and actually using the B12 in your cells.

Active B12 measures the amount of B12 that is bound to the protein that allows it move form your cells to your blood. Generally it is about 20% of the total amount of B12 in your blood. The ratio being screwed could be indicative of a problem with this process.

Things can be wrong with at the cell level but these tend to be rare and genetic in origin. MMA/homocysteine can be useful in identifying if your cells don't have enough B12 to run all the processes they need to run. They are waste products that will build up if your cells don't have enough B12 or can't process the B12 properly.

I think your best bet at the moment would be to try and get your GP to recognise that there are two protocols for treating B12 deficiency - and that you should be being treated with the protocol for neurological involvement unless there are good solid grounds for believing that the neurological problems aren't connected - even if they aren't there may still be a benefit in following a more agressive treatment as there are many studies showing that MS patients can benefit from B12 treatment.


Hi, many thanks for your reply. My doctor is not much help and didn't think my total b12 level was that low at 122. He seems to be ignoring my masses of symptoms that nobody has managed to diagnose properly as mentioned in last post, and others such as optic neuritis in the absence of MS, I am also aneamic, with palpitations with mood swings, and severe memory problems where I couldn't even remember my own childrens names Last week! If I don't get anywhere with my GP can you recommend what dose I'd be best on and how often as i will source them privately rather than risk my health anymore.

Kind regards


there are different types of anaemia - do you have macrocytic anaemia - in which your red blood cells are larger and rounder than they should be - it's a common symptom of both B12 and folate deficiency. Microcytic anaemia - in which your red blood cells are smaller than normal is indicative of an iron deficiency.

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Hi Chippy82

"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."

Treatment of cobalamin deficiency

Current clinical practice within the U.K is to treat cobalamin deficiency with hydroxocobalamin in the intramuscular form outlined in the British National Formulary, BNF,

Standard initial therapy for patients without neurological involvement is 1000μg intramuscularly (i.m.) three times a week for two weeks, then every three months.

The BNF advises that for Pernicious anaemia and other macrocytic anaemias patients presenting with neurological symptoms should receive 1000μg i.m. on alternative days until there is no further improvement, then 1 mg every 2 months.

However, the GWG recommends a pragmatic approach in patients with neurological symptoms by reviewing the need for continuation of alternative day therapy after three weeks of treatment

What dosage of B12 is your doctor giving you?

It is also important that your Folate level is monitored as this is essential to process the B12.

There is a complex interaction between folic acid, vitamin B12 and iron. A deficiency of one may be "masked" by excess of another so the three must always be in balance.

Symptoms of a folate deficiency can include:

symptoms related to anaemia

reduced sense of taste


numbness and tingling in the feet and hands

muscle weakness


Folic acid works closely with vitamin B12 in making red blood cells and helps iron function properly in the body.

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

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Hi, thanks for your reply. I am actually low in folate too but haven't been prescribed anything for it as I cannot take anything orally. Do you know what my options are for that?

Kind regards


I'm sorry I cannot find any reference to injectable Folate (Vitamin B9) under the U.K. NHS.

It is available in the United States, for example:


As I said before, I am not medically trained so it's best you speak with your doctor about this.

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Hi Chippy82,

There’s a charity set up by a retired doctor B12d.org who try to help patients suffering with symptoms but are struggling to get anywhere with their own gp. The doctor is retired but if you contact them via their website he will call you back. I had a call back the same day and they helped me start to self inject. My symptoms hadn’t progressed as far as yours sound but I had become immobile very quickly. As soon as I started on the shots I was moving about again within a couple of days. They were really helpful and supportive.

I would push your go to refer you to a neurologist as well, to cover all bases they should be doing a scan to rule out ms for sure..

I hope you see a change soon..



Hi, thanks for your reply. I have many doctors including neurologists who initially thought I had ms... then mito as i have diagnosed nerve damage and nervous system failure but it was put down to unknown origin and I've now been written off by drs who say they can't do anymore for me. I'm under palliative care team, local hospice and wheelchair to Bed bound and maintained nutritionally through a hickman line as my digestive system is also completely paralysed. I am staying positive that even after all this time I may still get some improvement. I contacted Dr Chandy yesterday and be was extremely helpful. Thanks again


It sounds like you have chronic b12 deficiency. Go to b12d website but for quickness start daily injections of hydroxocobalamin get the Needle from medisave b12 from mycare.de. Go on b12d and it will tell you lots. I have been injecting myself for 6months but I still have a long way to go.

The NHS won't help u they give 1 injection /month who are they kidding

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Hi, thanks for your reply. I just looked at the website you recommended for the b12 and it was cheaper than the one I just ordered from so will be using that site in future. My doctor has not been helpful in the slightest and didn't listen to me at all when asking for higher dosage, just wanted the hospice to put me on yet more strong pain relief even though I'm on fentanyl and morphine ivs which i hope to reduce eventually not become addicted to yet more strong opiates! I hope it isn't too late to reverse some of the damage, I'm remaining positive. There is some hope as i was just slowly dying until now, where I now have hope which is something in havent felt in a long time. If you dont mind me asking..... when yoj first started b12 did you feel much worse? If so... how long until it settled. Thanks again


Oh good grief! These doctors are less than useless. What could be the harm in giving a hospice patient b12 injections every other day until no further improvment as per guidelines? It is not toxic and so inexpensive and has helped countless patients.

I would demand every other day injections (per guidelines) and tell them i was going to self treat if they refused and threaten to sue them if they continued to refuse every other day injection until ni further improvment. This can be for months or years even.

122 is very low!!! Do not let them tell you otherwise!

I would point out that you have macrocytosis and the fact they let you get to this point is unacceptable. I would explain the your folate is also low and as medical professionals they had better figure out how to get your folate levels up so that the b12 can actually work.

Thank god you have found this forum as it sounds as if they had essentially given up.

Vitamin D is commonly low in those with absorbtion issues and lack of D causes pain. You will need magnesium to utilize D but hopefully they are giving you magnesium in your parenteral nutrition.

Please ask your kids, if they are adults, to sign up to this forum so they are knowledgeable about all the issues a b12 deficiency causes and they can advocate for you instead of you having to do it yourself, especially when you need to be as low stressed as possible.

Hugs for you in your time of need.


I am only 35 so my kids are young. I have very low vit d and use a daily spray, have osteoporosis. My magnesium and potassium drop quite a bit due to regular vomiting with my condition so although I get those in my tpn I still have issues keeping levels up. I am going to self treat as I'm not letting their ignorance prevent any possible chance of recovery.

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