B12 Functional deficiency: Hi - Please... - Pernicious Anaemi...

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B12 Functional deficiency

Riseup01 profile image

Hi - Please can anyone shed some light on B12 Functional deficiency.

My levels are mostly high (around 1400 - 1500), I still have fatigue and weakness. Could this be because of something else.

47 Replies

Normal B12 range ( 300- 900)

Have you been having injections or any other kind of supplementation? And have you been given a diagnosis?

I was on injections (every 2 month) but was also "off and on" on Oral. Currently I was only on Oral which is keeping my B12 level high

.. My levels are still high but still I am struggling with little exertion... I am also getting chest pains though my ECG came out normal.

Not sure what is wrong

Retteacher profile image
Retteacher in reply to Riseup01

Are you getting breathless after little exertion? I think that you should talk to your doctor about your chest pains, as a simple ECG is not sufficient to exclude heart problems. Fbirder's experience is similar to my own, in that MMA and Homocysteine are presently reported as in the normal range. However, the Mayo Clinic have just published a paper declaring that all the B12 tests can be unreliable. I believe this is especially so when a patient is receiving B12 supplements. The Dutch Haemotologist who spoke at the recent PA Society meeting reiterated this and said you had to be off supplements for 6 months to allow these tests to give a baseline 'proper reading '- not something that is recommended.

My own GP is resisting giving the B12 injections and it is only after six months of heart tests that he is grudgingly accepting that something else may be wrong. My husband thinks that my treatment for hypothyroidism is now wrong as well as this gives many similar symptoms. Don't be alarmed, but see your doctor again to exclude all possibilities.

Riseup01 profile image
Riseup01 in reply to Retteacher

Thanks for sharing your views and experience.

ECG has been done twice, it is fine. More heart tests are schedule for coming Monday.

My GP thinks it's anxiety, don't know what's wrong.

I am damn confused with B12.

I think my body is getting adjusted basis the B12 levels.. Seems my new normal is over 2000 ( just my theory)

Riseup01 profile image
Riseup01 in reply to Riseup01

I have done Echo and TMT and both came out normal. Though I was struggling with exertion not sure how I managed the Treadmill.

The whole battery of blood test (iron, folate, CBC etc) also came normal.

My Dr told me there is something wrong with your mind ( he litterly said that).

He said .. don't take any B12 now.. your levels are already above..

Do you have a link for the Mayo Clinic paper on B12?

Thanks, Sita

It is a paper published in June 2019 in the Mayo Clinic Proc.:Inn.Qual.Out. Vol. 3(2) 200-214. I don't know how to set up a link but it can be googled for free. The authors are actually from the Netherlands.

Thanks very much!


"Mayo Clinic have just published a paper declaring that all the B12 tests can be unreliable"

Do you have a link to this paper? Thanks...I think many on forum would find it useful.

Hi, the paper is 'The many faces of Cobalamin (Vitamin B12) Deficiency' published in June 2019 in 'Mayo Clinic .Proceedings: Inn.Qual.Out. Vol 3(2)pp200-214. The authors are actually from the University of Groningen, Netherlands rather than the Mayo Clinic itself. I am not sure how to create a link but it can be googled for free. There are several interesting comments within it. Best wishes

Martin_12 profile image
Martin_12 in reply to Retteacher

Hi Retteacher

I am also interested in the Mayo Clinic article declaring that all the B12 tests can be unreliable. Do you have a link to it?

Many thanks.

Retteacher profile image
Retteacher in reply to Martin_12

The paper is published in the 'Mayo Clinic Proc: Inn.Qual.Out Vol. 3(2) pp 200-214 June 2019. The authors are from the University of Groningen, the Netherlands. There are several interesting comments about the lack of knowledge regarding the sensitivity of the MMA and Homocysteine markers and how they can be normal in symptomatic patients.

Thank Retteacher and Martin_12

I'm hoping I'll get some insight into why I was symptomatic for B12 deficiency for many years with virtually every test normal range.

I think it documents that this happens. I am not sure anyone knows why , although even low levels of supplementation can interfere with the test levels. I think this review points out to doctors the limitations of the 'best diagnostic test protocol. It could well provide the basis for a clinical newsletter from the Pernicious Anaemia Society. I am not sure that it will convince intransigent GPs because it is based on case studies, but it ought to raise doubts in their minds. My husband is going to use it to rattle several Consultants cages who don't seem to realise that their tests have very real sensitivity problems - listen to the patients, treat the symptoms not the lab test values. The table reporting symptom relief after six months of treatment is very interesting.

This paper was cited by Dr Auwerda, Consultant Haematologist from Amsterdam when he spoke at the PA Society meeting in Cardiff earlier this month. He sees 1000 patients a year and reported his own evidence of the limitations of the lab tests. He says that you would have to be off all supplements for 6 months to get unaffected results. His treatment results are very good. 50% of his patients have all their symptoms resolved and another 39.6% have some of their symptoms resolved with B12 injections.

I hope that you find it helpful. My husband is extremely pleased with it, for asking all the right questions.

Martin_12 profile image
Martin_12 in reply to Martin_12

Thanks Retteacher. Here's the link:


A functional deficiency is when you have lots of B12 in the blood, but it is not getting into the cells to do its job. To determine the latter you need to have tests for methylmalonic acid and homocysteine. These are chemicals used up in two of the reactions mediated by B12. If it's not getting into right places in the cells then one, or both, of these will have raised levels.

Having said that, my MMA and hCys are both low but I still fatigue very easily. Cooking Xmas lunch yesterday got my energy levels low enough so that carrying three lots of presents from one room to the other had me gasping for breath for 5 minutes.

I'm sure there's something about B12 that we don't yet understand.

Riseup01 profile image
Riseup01 in reply to fbirder

Thanks for your advise fbirder

Gambit62 profile image

Nobody knows exactly how functional B12 deficiency occurs. It just seems to be a response that affects the efficiency with which B12 is transferred from your blood to your cells. As it is affecting the efficiency that means that raising/keeping B12 levels higher means that enough can get through. There are a lot of processes that go on in cells that use B12 and depending on genetic variations some may run more efficiently and others less - which may be why high MMA and high homocysteine aren't always there.

Thanks for your advise Gambit

Have you had Ferritin - Folate - VitD tested ? If Ferritin is low then ask for a full Iron Profile.

Low iron = Low oxygen = fatigue... in simplistic terms ..

Riseup01 profile image
Riseup01 in reply to Marz

Iron and folate all came out normal! All heart related test also came out normal.. Back to square one.

Marz profile image
Marz in reply to Riseup01

Normal/fine/ok are opinions and mean you are within a broad range. When we are unwell it is where we are in the range than can be important and make a difference. Do you have the results with ranges ?

Riseup01 profile image
Riseup01 in reply to Marz

Yeah Sure .. Here you go

.. Iron 121 ( range 65 - 175)

Total Iron Binding Capacity 365 (250 - 425)

Transferrin Saturation 31.43 ( 20-50)

Ferritin 70.50 (22- 322)

Vitamin D - 76.12 ( 75 - 250)

Folate - 12.89 ( >5.38)

Marz profile image
Marz in reply to Riseup01

Looking good ! VitD may be better with a boost - especially now it's winter. Am assuming thyroid has been correctly tested ?

Riseup01 profile image
Riseup01 in reply to Marz

Yes, it's fine.

T3 Total - 1.08 ( 0.60 - 1.81)

T4 Total - 5.50 (5.01 - 12.45)

TSH 2.28 (0.35 - 5.50)

I will take the supplement for Vitamin D soon :).. otherwise it all starts with its own set of problems

Riseup01 profile image
Riseup01 in reply to Marz

Just to add, I also have an undiagnosed auto immune disorder or disorders, I don't know ;)

Marz profile image
Marz in reply to Riseup01

Yes auto-immune issues can be a problem. I have Crohns and Hashimotos ! So tests to rule out Hashimotos are for the anti-bodies Anti-TPO & Anti-Tg.

I think you have had the Total T4 and Total T3 tested rather than the Free - which is the amount available to reach your cells. Both results are on the floor.

When taking VitD I am wondering what you take? VitD is fat soluble and needs the co-factors Magnesium and VitK2-MK7 ...

Riseup01 profile image
Riseup01 in reply to Marz

I just take vitamin D supplement 63000 IU weekly.

I take multivitamin which has Magnesium but not with Vitamin D

Marz profile image
Marz in reply to Riseup01

As a rule multi-vits are not so beneficial as taking the supplements you need ... Does your multi-vit contain iron or calcium ? - if so then they will bind to other ingredients and negate their action.

Not all magnesium is well absorbed and some better than others.

When taking such a huge dose of VitD you will be increasing the uptake of calcium from foods. You do not want this hanging around in the arteries or soft tissues so it is important to take the K2-Mk7 mentioned above to direct calcium into bones and teeth.

I mentioned thyroid anti-bodies - you didn't respond.

Which brand of VitD are you taking and which Multi- Vit ?

Riseup01 profile image
Riseup01 in reply to Marz

Thanks for sharing your insight!

My multivitamin doesn't have iron and calcium, somebody told me both are not good (in their own way).

I don't take any K2 or Mk7.. that's a good suggestion, I can consider it.

I don't know I still feel breath less at times specially when I lay down on bed.. ( Google will sell you "heart failure" for these symptoms, I but do believe I have some kind of sleep apnea too..

I haven't done any thyroid antibody test yet. I thought as my thyroid tests are normal, I don't need any...

At times I think, I am thinking too much about my problems 😉

Marz profile image
Marz in reply to Riseup01

Your thyroid test results are for the Total T4 and Total T3. The Free T4 and Free T3 are better tests as they indicate the amount of thyroid hormone available to reach the cells where it is needed.

My thyroid test results for TSH - FT4 - FT3 were all in range back in 2005 but anti- bodies were high and Hashimotos was diagnosed ... and I began my journey.

You can click onto my username above and read my Bio - only takes a couple of mins 🤔 I am not medically trained but have had to learn so much along the way ..

Riseup01 profile image
Riseup01 in reply to Marz

Thanks Marzi! I will go for anti thyroid test as well next week.. anything which points to correct diagnosis will help.

Just went through your bio.. what a journey

.. may be you can suggest some yoga links to me to go through.. heard it works fine


Marz profile image
Marz in reply to Riseup01

These are the tests - FT4 - FT3 - TSH and Anti-TPO & Anti- Tg are the anti-bodies.

It may be better to take the B Complex in the morning as some of the B's can be stimulating.

When taking such a high quantity of D it is important to also take Magnesium and K2-MK7. When your loading doses of VitD have finished I would re-test as you may need a maintenance dose. I lived in the sun for 15 years but still needed to supplement.



Yoga is a very personal journey - you are in the right country to experience great practices. Look for Hatha classes/books/videos ..

Ray Long has a great website and books - an orthapaedic surgeon and yogi - I have several of his books.

Riseup01 profile image
Riseup01 in reply to Marz

Hey thanks again for your advise Marz,

I will look for Vitamin D combination with Mag and Vitamin K.

Also I will try for suggested thyroid test shortly.

I am seriously considering some kind of effective Yoga and will explore suggested links..And I also believe our body has innate ability to heal itself..

As you have rightly mentioned, in this part of world there are multiple Yoga practices, sometimes choices creates confusion :).

By the way, what maintenance dose you follow for B12..

Marz profile image
Marz in reply to Riseup01

I inject B12 weekly ...

Riseup01 profile image
Riseup01 in reply to Marz

Okay - i have tried methylcobal shots, while earlier they went smooth but now they give me some side effect (at times i get a minor autoimmune flare), hence I switched to Oral B12.

Once a week, do you also have a functional deficiency ..

Do you take Cyno or methyl?

Marz profile image
Marz in reply to Riseup01

I inject Hydroxocobalamin. I am without a Terminal Ileum due to lots of gut surgery and was not told of the consequences. Then the Peripheral Neuropathy kicked in - sigh !

Riseup01 profile image
Riseup01 in reply to Marz

It's really hard to find Hydro ..as methyl is so prevalent here..

At times I think whatever is happening right now is because of B12 but then I looks at my levels (1100-1200),

I mean I can't have such severe symptoms at these levels ..

Though I know I have to check for other things ..

Marz profile image
Marz in reply to Riseup01

Ruling out other conditions is key. B12 and thyroid issues have many overlapping symptoms. Look at the list in the link below.



"I was on injections (every 2 month) but was also "off and on" on Oral. Currently I was only on Oral which is keeping my B12 level high"

There are some forum members who cannot manage on the recommended levels of treatment and have injections weekly , daily or even twice daily.

I'm curious at to why you are only currently on oral. Did your doctors stop your injections?

If you have an gut absorption problem eg PA (Pernicious Anaemia), Coeliac and there are other gut issues that lead to b12 absorption problems then my understanding is that most countries recommend B12 jabs.

I'm in UK, and here the recommended treatment is B12 injections.

Next link is to a detailed reply I wrote on another thread with lots of links to b12 info eg books, b12 websites, UK B12 guidelines etc. Some of the info may be UK specific.


I am not medically trained.

Thanks for sharing your insight! I wonder if I inject every day I may become Superman.

This B12 deficiency is really becoming a mystery.

I stopped injection because oral was working for me in terms of raising levels..

I am one of those that require daily B12 injections, at my last blood test, where I’d been on this regime for about 8-10 weeks, my levels were only sitting around 1800. My endocrinologist was surprised as she expected them to be much higher. She said I clearly have a functional B12 deficiency although I’ve not been tested for it specifically.

I’m still getting very breathless, even sitting up when I’m in bed can leave me breathless for a good few minutes and sometimes it can happen when I’m just sat watching tv!!

I have tried missing a day to try and go every other day, but it didn’t work, by teatime of the second day, I was out cold and slept for almost 19hours!!!

Get tested for the other things that Marz has advised and don’t forget to provide reference ranges when you get results. Good luck

Shelley x

Riseup01 profile image
Riseup01 in reply to LuluCops

Thanks for sharing your experience! Well - I have heard it takes minimum 2-3 months for B12 to actually start working with RBCs or getting synthesed in blood.. one of the reason why it takes longer to recover..

Do you know why B12 doesn't stay in your blood for long ( any diagnosis) ? Is this functional deficiency, I thought it is about having high B12 in blood but still struggling with it's symptoms, may be my understanding is wrong..

fbirder profile image
fbirder in reply to Riseup01

It takes a few weeks before the macrocytosis caused by a B12 deficiency is effectively rectified. Normally it takes about three months to completely recycle all the red blood cells. But when B12 levels pick up then the body goes into a spurt of production of good cells.

B12 does stay in your blood, for quite a while. Obviously, the amount in the blood has little bearing on symptoms in some people. There must be other factors involved. Factors that are, currently, unknown.

Riseup01 profile image
Riseup01 in reply to fbirder

My experience from whatever I have read online and on this forum makes me think that all Functional deficiencies are linked to some kind of autoimmune disorder (in addition to PA)

Simpler dietry B12 deficiencies are much easy to treat ( as we all know) ..

Though, I mean, I am no medical expert.

You're assuming your symptoms are related to B12 deficiency. It could be your sex-hormones (estradiol or testosterone), adrenal hormones (cortisol and DHEA), or thyroid hormones are low. Very low levels of any of these, especially cortisol and thyroid, could cause many of the fatigue symptoms you describe. You should check these. Did you check your ferritin-could also be iron deficiency. Symptoms and signs of the hormonal deficiencies above are somewhat unique to the hormone, so look these up (e.g. thyroid deficiency symptoms).

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