Pernicious Anaemia Society
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Advice re next steps

Hi folks,

I'm debating different courses of action following recent blood tests, and would very much appreciate your experienced input, if you can spare the time, as to the best one.

I've had a range of symptoms (summary below), some for over a decade, but no abnormalities in blood & reflex investigations, so GPs have insisted that it must be psychological.

After receiving cognitive behavioural therapy, I stopped asking GPs to help me, & have been working on improving diet & fitness. But I'm still in constant excruciating pain & very tired each day. Concentration is all over the place & I’m forgetting words & how to spell, which is a problem because I earn my living by writing.

My most recent blood tests [22.02.17, FBC + thyroid function, requested because Mum was diagnosed with underactive thyroid & wanted to check mine is ok] showed:

Ferritin 158 ug/L [10 - 291ug/L]

Haemoglobin 140 g/L [115 - 165g/L]

Serum free T4 level 15.4 pmol/L [10 - 22pmol/L]

Serum TSH level 3.3 mU/L [0.1 - 4mU/L]

MCHC 332 g/L [320 - 360g/L]

MCV 97.7 fL [76 - 100fL]

MCH 32.4 pg [27 - 32pg]

So, all but MCH "in range". Both MCV & MCH have been right at the top of range for every FBC I have on record, and a trend line through the results shows them increasing. So I googled them, and consequently learnt about B12 deficiency on the NHS, PAS & British Journal of Haematology websites, along with some forum anecdotes from sufferers.

It felt rather like fireworks going off, because the descriptions of B12 deficiency very accurately match what I've been experiencing. [In the forum anecdotes, right down to odd little details like my right little finger being permanently numb, and not getting immunity from my measles vaccinations].

So I went back to GP.

She said would be v surprised if it's B12 because haemoglobin's ok, & got a bit miffed when I mentioned that BJH said symptoms more important than blood tests, but sent me for B12 & folate tests anyway.

These have come back today:

Serum B12 372 ng/L [180 - 910ng/L]

Serum folate 9.1 ug/L [> 5.4ug/L]

So, well within range, and the note says "no action required". The BJH best practice flowchart on here has me outside the reference range for another b12 check in a couple of months.

But several reliable sources online [ie., peer reviewed & not trying to sell me supplements or a book] say that <400ng/L can still cause symptoms.

My questions for you:

1) I've found sources online that say the serum B12 test should've been a fasting blood test, but I was told at the surgery that I didn't need to fast. Which is correct?

2) with your experience of UK GPs, would you recommend I either

hold off supplementation and asking for another b12 serum test in 1-2 months [NB: I feel pretty desperate because of the pain] and


supplement with sublingual high dosage just to see if it makes any difference to the symptoms, then returning to GP if it does, saying "look 'ere missus", and asking for more tests/injections


ask my nurse friend to teach me to inject, buying ampoules from Germany & seeing if that makes any difference


accept that I’m barking up the wrong tree with b12?

I am very fed up indeed with being in pain and unable to concentrate on work, and it’s very embarrassing/disheartening to keep asking the NHS for investigations when nothing looks abnormal to them; it's fair enough, since there’s nothing in their guidelines to say they should keep looking, based on tests so far. So it's deeply tempting to stop asking them, and self-treat. I suspect they'd prefer if I did that, too!

However, I don’t know what I’m doing re dosage, interactions, contraindications, what else I need to take with it, and how long I should treat before giving it up as a red herring. Self-treatment would also all be off-record - not ideal if anything goes wrong in the future. If it does work, it won't help other people who approaches the GP with similar symptoms. If it doesn’t, I’m back to square one, with a lot less money in the bank.

Whaddya think?!

Thank you very much.


[Summary of all main symptoms, regardless of what they might mean!

Constant: muscle & joint pain, burning sensation (particularly feet to mid thigh, hands to mid bicep, spine & neck; pins & needles (feet, hands, face, tip of nose); muscle spasms (thighs, back, face); weakness (esp arms & hands - carrying plates is a problem); exhaustion; breathlessness; confusion, forgetfulness (intent, names, words, what the hell I was saying mid-sentence); poor concentration; dermatitis; back-to-back ENT & chest infections; trouble tasting/smelling; thinning hair; trouble losing weight (I manage 5 miles total gentle walking a week, so may just be more calories in than out). Frequent: tinnitus & whooshing sounds; palpitations & audible heartbeat; headaches & migraines; blurring vision, lights in vision; dizziness & unsteadiness (esp when going down stairs, dressing); diarrhoea & sudden urgency, bowel pain (lower left - has been ultrasounded with nothing untoward seen). History of depression, now well managed via CBT & meditation. ]

4 Replies

amount of B12 in your blood is only part of the story with B12 - because B12 deficiency isn't about what is happening in your blood but what is happening at the cell level. For reasons that aren't fully understood but probably have a lot to do with genetics people vary a lot in how B12 behaves in their blood and how this relates to the amount available at the cell level so ...

serum B12 isn't a good test to use as a single measure for B12 deficiency. Using it as a single measure will result in missing 25% of people who are B12 deficient (and picking up 5% of people who aren't - but as they wouldn't have symptoms so wouldn't have asked for the test the risks on that are slightly lower).

The anaemia caused by B12 (and folate) deficiencies results in larger rounder red blood cells - and your MCV aond MCHC are on the high side indicating that this could be going on.

Although many medics seem to be of the impression that macrocytosis has to be present for B12 deficiency to be going on at least 30% of people with B12 deficiency will present with other problems first. These problems will be caused by the effect of not having enough B12 for processes that aren't related to production of blood cells such as maintaining the lining around nerve cells, mediating in the release of energy in cells and recycling neurotransmitters. BCSH guidelines recommend treatment based on symptoms rather than blood test results (serum B12 and/or full blood count) if there is a discrepancy between the two - to avoid the risk of irreversible nerve damage if a B12 deficiency is left untreated for too long.

An iron deficiency will result in lower haemoglobin but this isn't going to be the case with B12 deficiency - the anaemia caused by B12 and folate causes problems by affecting the efficiency with which oxygen can be absorbed and released by the cells - to do with the fact that cells have a much lower surface area/volume than healthy normal shaped cells.

Not aware of anything that would indicate that B12 should be a fasting blood test. Some labs do recommend folate is done as a fasting test but not sure that that is entirely necessary either - however, there is a much stronger relation to food intake and amounts in your blood with folate than there is with B12 because folate isn't stored anywhere in the body but B12 is stored in the liver.

There are a couple of other markers that can be used to investigate a suspected B12 deficiency where other indicators are ambiguous - these rely upon looking for evidence of that cells don't have enough B12 - eg raised levels of MMA and homocysteine because the body doesn't have enough B12 for the processes that recycle them into useful building blocks to work properly. They aren't front line tests because they can also be raised by other factors but it might be worth trying for MMA.

Your B12 levels are a bit of a way off the bottom of the range but that doesn't mean that B12 couldn't be a problem. Symptoms are really important in evaluating a potential B12 deficiency but can also be problematic because they overlap with other conditions such as thyroid, vit D deficiency and diabetes ... and it is quite common to have more than one thing going on.

I would definitely recommend holding off on supplementation until you really have exhausted every possibility of getting a diagnosis - in part because if you have an absorption problem it helps to know what caused it (eg PA, Coeliacs, Crohn's, gastric surgery affecting the ileum, h pylori infection, and a whole raft of drug interactions). Some causes can actually be treated - eg h pylori - but others will need injections for life) as there can be other consequences of the different problems so good to know which ones you need to look out for.

Another reasons for avoiding supplementation without diagnosis is the possibility of starting a functional B12 deficiency (some people respond to high levels of B12 in their blood by trying to shut down the mechanism that transports B12 from blood to cell leaving cells deficient) - ironically the best treatment for that is raising B12 levels even more but that means you get trapped into having to supplement at stupid levels.

Suggest that you right to your GP drawing attention to the limitations of the tests and BCSH guidance in respect of the importance of evaluating symptoms and also listing the symptoms you have - use the materials in the pinned posts - and then arrange an appointment to speak to them - you could also make them aware of this site



Thank you very much!


"Another reasons for avoiding supplementation without diagnosis is the possibility of starting a functional B12 deficiency (some people respond to high levels of B12 in their blood by trying to shut down the mechanism that transports B12 from blood to cell leaving cells deficient) - ironically the best treatment for that is raising B12 levels even more but that means you get trapped into having to supplement at stupid levels."

What is your source for this information?


These are some links on functional B12 deficiency:


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