After receiving some very helpful replies on my previous thread, I've been reading around a lot on here, but something I haven't been able to clarify is what exactly the MMA test does and doesn't tell you. My understanding is that it's a more sensitive test to identify a B12 deficiency than total or active B12, but am I right in thinking that it doesn't help to distinguish whether the cause is pernicious anaemia or gastrointestinal absorption issues?
I understand the IFAB test is usually used to identify PA, but is not necessarily that reliable. So if the IFAB test was negative, how would you know whether the cause of a deficiency was due to PA or gastrointestinal issues?
Hope I'm making sense!
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fleurdelis01
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If you have a B12 deficiency, yet you consume plenty of B12 (i.e., you're not vegetarian/vegan) and you don't destroy any B12 you may consume (i.e., you do not abuse nitrous oxide) then you almost certainly have a n absorption problem.
If you have a problem absorbing B12, you have not been diagnosed with another GI problem (coeliac's Crohn's, etc), you are not taking certain drugs that can interfere with B12 absorption (PPIs and metformin), you do not have a fish tapeworm - then you almost certainly have PA.
This 'it isn't anything else so it must be PA' method of diagnosis doesn't sit well with some doctors. If you have one of them then ask them what is causing your deficiency. They will respond that it's 'probably PA'. Your response should be 'then we should probably treat it as PA'. Some might say 'we don't know'. Your response should be 'what is the difference in treatment between don't know and PA - and why?'.
I got a definite definition of PA without every having had a IF antibody test. When my idiot haematologist said I didn't have PA because I hadn't taken the test (not that I tested negative - he thought not having had the test ruled it out) I asked him what caused by undetectable B12, positive GPC antibodies, autoimmune gastritis and high gastrin. He conceded that I probably had PA.
So, on to MMA.
Methylmalonic acid is a chemical used up in one of the reactions mediated by B12. If you do not have enough B12 in your blood, then MMA will be high. A good sign of a B12 deficiency.
If you do have lots of B12 in your blood but, for some reason, it's not getting to the right place in the cells, or it's not being converted to the correct form of B12, then MMA is raised. That's a good sign of a functional B12 deficiency.
But there are other things that can raise MMA levels. Problems with liver and/or kidneys are the most common. So raised MMA isn't a definite sign of a B12 deficiency until other causes of the high levels are ruled out.
Note that high MMA can only indicate a deficiency, not what causes that deficiency. So it's not much good for diagnosing PA.
Ideally it wouldn't matter if your deficiency was diagnosed as PA, or 'probably PA', or 'AbNegPA', or 'something else that looks like PA'. Ideally all of those would be treated the same. But we do not live in an ideal world with ideal doctors. We have real world doctors, some of whom have an insatiable desire to stick people in boxes and to treat them depending on the label on the outside of the box.
Thank you so much for your detailed reply and clear explanations - this is so helpful.
My recent active B12 test was in range, but in the bottom 10%. I am experiencing a lot of the relevant symptoms including quite intense neurological symptoms.
It's worth mentioning that my folate was out of range, and I am aware that resolving this deficiency will help, but I am also concerned about my B12 levels.
I have been very ill for the past couple of years (diagnosed with CFS), but these symptoms have developed over the last few months - I wasn't getting the neuro symptoms or breathlessness previously. I am desperate to feel better, and concerned that these new symptoms are being lumped under the CFS diagnosis umbrella without properly exploring other possibilities. I also have hypothyroidism/hashimoto's so PA doesn't seem beyond possibility. So I am just trying to get myself clued up to advocate for myself.
I do have an IFAB test in a few weeks but am half expecting a negative/inconclusive result, so just trying to get myself prepared for the next steps. Based on what you've said, it sounds like asking/paying privately for an MMA test wouldn't necessarily add much value, and that I'd be better off pushing for a PA diagnosis and treatment based on my symptoms and the absorption issue argument. Would you agree with that?
Edited to add:
Not vegetarian or vegan and don't abuse NO or take a PPI or metformin. Have been tested for coeliac previously (negative), never explored Chrohn's or fish tapeworms as far as I'm aware.
MMA is sometimes used as a reliable secondary indicator of a B12 deficiency/ functional B12 deficiency. The test is quite expensive and so not usually offered at local hospital labs.
It does have to be quite high for consultants to take it seriously .
My MMA, despite regular injections and a B12 level that was then at >2000 ng/L, was raised and functional B12 deficiency diagnosed by GP, confirmed by lab. Renal impairment ruled out. Loading frequency of injections was restarted.
After having MMA checked five times by haematologists, consistently at 350-400 nmol/L (range: 0-280), I had a hydrogen breath test for SIBO (small intestine bacterial overgrowth) which was inconclusive: either indicating SIBO or IBS. SIBO can cause B12 deficiency because the bacteria feed off some of your vitamins, including B12.
Since I had been sent there originally to determine if my raised MMA was due to SIBO, my GP put me on a trial of antibiotics - to which I had an adverse reaction: vertigo and headache - but no improvement in my condition. So probably not SIBO (?)
So all of this has left me with no clear direction:
My GP believes raised MMA to be a rare condition- she recognised that I could have functional B12 deficiency, after injections started for B12 deficiency, because I got so much worse after loading injections finished and having to wait 3 months for another one. She had my MMA tested because of a similar case 10 years previously. She knows of no other case.
The consultants believe otherwise - that MMA would have to be several times higher for them to attribute this to functional B12 deficiency. It was decided that my raised MMA level was probably normal for me.
Having no other diagnosis to work on, Coeliac disease and SIBO having been ruled out and IBS (like CFS) being merely a set of symptoms NOT a diagnosis and in any case not considered my problem by GP or myself, I decided to self-inject every other day as functional B12 deficiency requires "frequent injections" (according to Turner and Talbot, 2009).
It has worked although it has taken a couple of years and I did have my doubts.
I'd simply run out of options and no-one who refuted my GP's original diagnosis could find an alternative, sensible or otherwise, for any of my symptoms together or separately.
I first went to the doctor in early 2015.
It is highly unlikely that PA will be diagnosed from an MMA test, but if it is high enough it could confirm B12 deficiency/ functional B12 deficiency as a secondary test. Only if renal problems and SIBO ruled out. Only if B12 deficiency already suspected.
Homocysteine level could be used as a third supporting test result if high enough - mine was normal.
IFab (anti-intrinsic factor antibody test) is usually used although as you say unreliable 40-60% of the time. A positive result however will be 95% reliable!
So what to do then ? Convince GP to give you a "best out of three" chance ?
Thanks for your reply. I'm sorry you have had such a difficult time getting a diagnosis and treatment. I am not holding out much hope for myself but am rather needle phobic so self injecting would be a real challenge for me!
Well if no-one seems to recognise B12 deficiency symptoms for what they actually are, there must be a specialist somewhere for each individual symptom. It takes time to get through that list.. If you do get all the way through the list and still have a problem, it's probably PA !
I would continue to hope. It only takes finding the right person and saying the right thing to get the right test done at the right time.
My problem with self-injection was not fear of needles, but not being able to get any professional help. I watched a Youtube video in the library (no computer at the time), then rushed home to do it before I forgot what I'd seen. Always better if you are relaxed, but how could I be, given that set of circumstances ? To be honest, I was a bit rubbish.
I have got better over time, but at my worst, I was inept, anxious, unable to make simple decisions and stick to them, or to concentrate, and memory was very unreliable ….. and that is not an ideal description of the person you would choose to inject you, is it?
It is B12 deficiency in a nutshell though - and the reason I knew I needed more injections - Catch 22.
Thank you for the encouragement, I appreciate it. I completely understand where you're coming from with regards to injection technique and feeling well enough to do it in the first place! If I end up going down this route I will def need to find someone to show me how to do it.
I'm so glad to hear that self-injecting has helped you get better.
A lot of people on here either know a nurse, have someone with medical training in the family, or have been taught what to do by the practice nurse or GP.
For those who haven't, there are youtube videos, which are less reliable and vary in advice : confusing. I chose the one with the most sensible pants and stuck to his technique, which worked for me, but a bit of a lottery. I asked a lot of questions on here, and got some really useful advice and tips, and encouragement from people I trust, before I went ahead.
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