Pernicious Anaemia Society
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Update and Question about MMA and Homosysteine: Post B12 Injections. Advice Please

Oh help! Here I am again!

The comedy of errors continues apace...

As per previous posts, I thought I was staring to convert my GP who went off to 'find-out' if I could have every other day B12 injections (due to ongoing B12 deficiency / neuro symptoms / B12 above 2000). He was going to speak to a gastro and neuro and ring me the next day. Two weeks on and no phone call!

Started self injecting.

Finally managed to get him to call me back after numerous calls to the surgery and, to cut a long story short, he said, 'Oh, I must have forgot!!!' He went off to make a call and finally got back to me this morning, having spoke to an on call neuro registrar.

I've no idea what he told him but I suspect that whatever it was was an incomplete picture of what's been going on (inadequate treatment for four years). The outcome is that the neuro is 'reluctant' to advise every other day injections and wants, instead, to do MMA and Homosysteine levels (so they'll be ready for end of June appointment.

So, given that I've already been having B12 (last injected 1mg Methylcobalamin 2 days ago), I just want to check my understating of what I've been reading here. Am I right to think that these results will be skewed because of B12 injections?

And more Important, will the MMA and Homosysteine levels still be high if I have a functional B12 deficiency, despite treatment?

And is there any point in stopping self injections (test will be end of this week) - think I suspect what the answer to that will be!

What would you do, carry on injecting, or stop?

I'm thinking now that, with potentially skewed test results, all I'm going to end up with is another string of reasons why I can't have more B12!

Might have been nice if these tests were done before B12!

Excuse me, but this is so frustrating. Battling with medics is like trying to nail jelly to the wall or knit with spaghetti, and it's wearing me out!

Most days I rail at the astonishing level of incompetence...but then I stop and wonder... Some days I think I might just be going MAD!

To all of you who've been here for a on earth do you manage to keep your cool!

There, that's me done. Thanks for listening. Again. Grrrr...👹

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28 Replies

Sorry that it is all so frustrating.

MMA and homocysteine are guides to what is happening at the cell level so they will continue to be high if you have a functional deficiency but will have fallen with supplementation if you don't.

I'm not sure about the timescales for the MMA and homocysteine but I suspect that (unless there is a functional deficiency) the time-scales won't be sufficient for the B12 to have dropped again.

Personally I gave up on medics ... though taking enough B12 is also a way of making sure that I keep my cool.


Thanks Gambit. I suspect that functional deficiency is the problem so, keeping fingers crossed that MMA and Homosysteine will be high. But isn't it odd to Have to hope for abnormal tests just so that someone will 'believe' and treat you!

Think I'll soon be giving up on medics too! Just having a final push in the vain hope that it might encourage them to be better informed so that other people may be able to benefit. Might be a vain hope.

I love the idea of keeping cool with B12. Shame it can't be made into ice cream.

Thanks for your words. Take care.

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may be it can't be made into ice-cream (and not sure that it would be helpful given the absorption problems) but I do find that methyl occasionally gives me an 'ice-cream headache' :)

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Excuse me being dim but could you tell me what functional deficiency is.

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B12 deficiency is not about the levels of B12 in your blood - it is about what is actually going on with B12 at the cell level. It is quite possible to have high levels of B12 in serum and yet for none of it to be getting through to the cells where it is needed - this is functional B12 deficiency. Think there is some ambiguity and some would consider that being normal range and yet having clinical signs of deficiency is an example of functional deficiency - and that is certainly part of what tends to come out in some of the discussions and papers. However, I think it is more accurately related to conditions where serum levels aren't just normal but grey-range but actually relates to levels that are higher than the grey range and seems to be the result of an auto-immune response to high levels in serum that binds the B12 into the serum preventing it from getting to the cell level. One study in denmark implied that up to 40% of the population respond to high levels of B12 in serum in this way. It's main significance though is probably that there are some other conditions that can result in B12 in serum being high so, in the absence of supplementation, high levels of B12 in blood can be an early indicator of problems.


Is there a way of diagnosing functional b12 deficiency?

Yes. Here's a cut 'n' paste of part of an answer I just posted -

Functional B21 deficiency is where blood levels of B12 are high, but symptoms of deficiency are still present. This can be determined by a test for one, or both, of two chemicals in the blood - methylmalonic acid (MMA) of homocysteine.

These chemicals are used up in two of the reactions mediated by B12. If there's not enough B12 in the cell then they don't get used up and the blood levels increase. So a blood test that shows that one, or both, is abnormally high - while B12 levels are high - is a good indicator of a functional B12 deficiency.


Thank you :)

I'm new here so still dim myself! I can give you a very basic explanation, based on information gleaned from other people on this site.

Serum B12 tests that the doctor does will tell you the total amount of B12 sloshing around in you body.

But...some of it is active (the cells can make use of it) and some of it is inactive (your cells cannot make use of it).

So... the serum B12 test does not tell you how the B12 functions in the body at a cell level (i.e. how much your body is able to use from the active cells).

So, what is important here is how much B12 your body actively uses, or to put it another way, how the B12 functions at a cell level.

Some people with B12 deficiency / PA may have normal or high B12 levels but still have the symptoms of B12 deficiency: they are said to have Functional B12 Deficiency (their bodies are unable - for some reason - to actively use and absorb B12 at a cell level). So, the B 12 is in the blood, sloshing around but not doing a lot - being inactive!

This is what I suspect I have.

Two of the ways to test for this is with an MMA and Homocysteine blood test. Fbirder explains these tests in the post after mine. Just to give you a flavour... Both tests before any treatment with B12 will show high levels. These levels will come down once B12 treatment has commenced. cases where functional B12 deficiency is present, the levels of both MMA and Homosysteine will remain high.

These are the test I'm going for.

There is another test called an Active B12 test, which tests the function of active B12 at a cell level but there are, according to what I've read on this site, problems with the accuracy of this test.

Apologies for the complete lack of 'technical stuff'. There are others here who can give a much better explanation, who I'm sure will reply if they spot this. Also- it's only my basic understanding so far, so might not be as clear or as accurate as it could be!

If you put functional B12 deficiency in as a search term, I'm sure lots of lovely stuff will pop up.

Hope this helps a bit.


Oh...I've just spotted Gambit's reply. Much more authorative than my newbie attempt. 😀😀😀😀😀

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I noticed that you are injecting with methylcobalamin. Even if you do get the every other day injections you want they will be hydroxocobalamin. It seems that you have no choice to continue doing what you are doing and hope for the best. At the end of the day you can do your own injections if you need to and you will have promoted a bit of awareness!

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Thanks Pugdogs10. You're right. Also have rock bottom ferritin, calcium and vitamin D (currently supplementing with the, also vitamin K 2 and magnesium). Potassium okay, at the moment. My next mission is to persuade the surgery to blood test every so often to make sure that these levels are in the right area and remain stable. Also need to research more to see if there's anything else I should take or keep an eye on.

My goodness, it's complicated, isn't it!

I would have been very lost had it not been for this space!

Keep well


It s a nightmare and what chance have we when the doctors can t get it right. I ve been trying to explain things to my husband and bless him he does his best but to be honest this forum is the only place you can get any real understanding. Good luck with everything.


Couldn't agree more. Likewise with my husband. Since I've been 'here' I think I've got some of my spirit back - he was the one who noticed. I hadn't quite realised.

Going to go the the Leicester support group when that gets back on track, so really looking forward to meeting people in a similar position. Makes a world of difference.

And good luck to you too. I'll watch out for you posts. X


And more Important, will the MMA and Homosysteine levels still be high if I have a functional B12 deficiency, despite treatment?

If you have a functional deficiency then the levels of the two markers should be high despite treatment.

But why do you think you have a functional deficiency? Yes, you have some symptoms that are only improving slowly, if at all. But that may be because the damage caused so far is, unfortunately, permanent. Do you get other symptoms that come and go between jabs? Do you feel fatigued for the days before your jabs?

I've written a long summary of what I think about the two tests. Here's a brief precis...

If you want to show functional deficiency then you need to test for the markers while supplementing. If you stop supplements for a few months and then test - well, you're just testing to see if you have a B12 deficiency.

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Hello fbirder. Yes to both. Symptoms (multiple) have been consistently been returning about two / three weeks after 3 monthly injection and gradually get worse until jabbed again. Fatigued - sometimes to the point of not being able to even speak straight. Basically, I just cease to function.

Suspect it might be functional deficiency as serum B12 levels above 2000ug/l (240ugL - 700ug/L), but still symptomatic.

It took two years of treatment until B12 levels even crept into the bottom of the scale and I was never given the 'dose' for neurological involvement, so it may be that some of the damage is permenant.

However, ever the optimist, I am hoping that I've had enough to limp along but not enough to effect healing. trying to persuade medics to let me try every other day, just to see if I can get some improvement.

Got to be worth a shot (excuse the pun).

It's all so very complicated and I'm really new to this so... feel free to tell me if I'm entirely misguided...

I've read your seperate post...great thanks. Will keep on with supplements!



Your case sounds just like mine. I hope that you get an MMA test and that it does show a functional deficiency. Then you'll have some real ammo to persuade them that something needs to be done.


Oh dear...I wouldn't wish anybody to have a case like mine! Having an MMA and homocysteine on Wednesday so, fingers crossed. Some ammo would be great...but they'll still take some persuading, I think.

Thanks again fbirder.

Excuse me being dim but could you tell me what functional deficiency is.

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A functional B12 deficiency is when there's plenty of B12 in the blood, but there's not enough getting to the places where it's needed. There are probably loads of reasons why this might be so. One is that there could be a problem with the protein that carries the molecule into the cells - TC2.

Some people, like me, have mutations in the gene that makes this protein (the gene is called TCN2) which can cause various problems. Interestingly, one of them is associated with Idiopathic Pulmonary Fibrosis - which is what my Dad had when he died.


Foggyness, it's just appalling isn't it. It gives you no faith when they can just forget about you, then organise tests that could and should've been done at the beginning, words just fail, don't they. Sadly though after reading so many peoples stories and through my own experience, it seems to be happening pretty consistently.

I was diagnosed with a ' functional b12 deficiency at tissue level' after having low Active b12 and high MMA (paid for test at St Thomas, Dr disagreed that b12 at 261 was causing a problem). I assumed the MMA will drop after getting b12 sorted, but reading this now I'm not so sure? Will try and find out more...

Hope you soon get some better results and the treatment you need...:)


Thanks Jojo54. Very much appreciated. Appalling just doesn't do it justice, does it! And so many of us! So sorry that you've experienced similar. And good for you, getting yourself 'sorted'. I'd love to know when doctors stopped looking at patients and started reading results!

Would love to hear if you find out anything else.

Thank you for your words and keep well.

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Hi foggyme (aka foggyness, sorry I got your name wrong last time! Just read this back before sending and realised I'd called you foggyness again, so corrected, oh to have a brain back!)

I contacted the hospital yesterday to ask about their definition of functional deficiency. I was told B12 is not used in the blood, it's only there for transportation and is used within the cells/ tissue to support the function of 2 enzymes. (Googled these and think they could be Methionine synthase and methylmalonyl-coAmutase, but I bet fbirder is really the man in the know to give more Info on this!)

The MMA tests to see if one of the enzymes are working properly. If it's not functioning properly because of insufficient b12 the level of MMA goes up. So functional deficiency is at the tissue level, as opposed to an abundance in the blood.

The function of the second enzyme can be tested by homocysteine. I didn't realise this and would have probably tried harder to get a private homocysteine test too.

If the injections are working then the MMA becomes lower. MMA starts to increase if a state is reached again when adequate b12 is unavailable.

I asked if it would be a good idea to test MMA prior to having an injection as a guide to see how often someone needs an injection and was given the above advice. I can also see it would be useful to have the test after having an injection to see if they are actually working as fbirder mentioned and lowering the MMA. Guess there are some people that this happens to, but have no idea what would happen next in regards for testing?

So I hope that helps with your question abit? I don't know if it takes MMA long to build up/ lower though, I could ask them that, so therefore if you decided to stop injecting before your test it could make a difference...will get back to you on that....

But it's all so difficult isn't it. I've read that some people can test low for MMA homocysteine, etc, but still improve with b12 injections, so I think there's an awful lot to be discovered in the future about this, don't you? The worst part, like you say that you feel you can be shooting yourself in the foot if these results read okay, and the Dr acknowledges them and not your symptoms, but that's if you can even get them to do the tests! My Dr never believed I had a problem with it when my level was 261, so it doesn't give me great hope in the future. He said I'd need a b12 test further down the line as it would be high at the mo, ( had to have folate tested and b12 was indeed >2000) but I still have symptoms and feeling pretty rotten, but am aware they can take time, so have no idea at this stage if monthly injections that I'm being allowed for little while are regular enough or not. Time will tell once I get to the 3-4 month stage I guess.

Are you seeing an improvement with your every other day injections? Really hope so.

Will read some of your other posts, should've done that first, that would have been more logical!

Take care...Jo

Hi Jojo5454. Thank you so much for the information and you're right, it is complicated. Very! I think I have lots of B12 sloshing around doing...not a lot! My level, like your's, is >2000. You must have worked a miracle to carry on getting jabs. Mine have been stopped (so I do them myself). All that B12 and I still feel quite terrible, to put a good spin on it!

I've had five every other day injections so far but little improvement, as yet (but, I did have one night of 8hrs undisturbed sleep. First time in years).

Really hope you start to pick up soon...isn't it awfully wearing just having to try to explain to others why we can't do anything! And then having to explain to ourselves that this might get day soon!

I've got two appointments coming up in June and July (gastro and neuro) and I'm going to go with a list of questions, which I'll put together from everything I find on this site.

Keep well and I'll post anything I find out.

P.s don't worry what you call me...foggyness is the state I live in almost permenantly. And I've been called worse.

Thanks again

Hello all, new to this and not sure if I'm on the right path, not long started B12 injections and wondering if these additional tests are available on the NHS before contacting my doctor to request. Thank you

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MMA and homocysteine are definitely available on the NHS. But your doctor will, almost certainly, ask why you feel they are required.

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Hi I've been getting b12 injections and levels over 2000. Symptoms improved a lot but got worse waiting for next jab.. now symptom are really bad again. If asked for folate (was 11.4 last Time tested) and ferritin (Dr says was 44 tested last sept) I also asked for MMA and homocysteine as I have before. Dr keeps refusing saying he can't order them a the lab won't allow it? They have to be ordered by a specialist. Is this correct I live in Salford Manchester if that makes a difference. Really struggling now and keep getting neuro sypmtoms (pins and needles not as bad as before), headaches, weakness, fatigue ECT.. . Any advice would be appreciated greatly. Drs are a nightmare! 😝😩

Lyndsay80. You've replied to a post that is two years old so the only person to see your reply will be me.

You'll obviously get more responses if the whole forum sees your question, so I suggest you put up a new post in the main forum so that all can see it and respond.

I don't have time for a proper response right now but will look out for your new post tomorrow and add a response there if I can add anything to whatever others have said.

Good luck 👍

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