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Pernicious Anaemia Society
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High MCV but acceptable B12 serum levels

Hi Everyone

I haven't posted here before and only on the Thyroid forum. I have posted my recent results for blood count and for B12. I am not sure why my MCV and MCH are always high or over range? I had severe megoblastic anaemia in my 20's (now late 40's). I only drink socially and very lightly. I don't eat much meat but have lots of dairy, eggs and green veg. My folate is 19.9 ! My B12 was 399 mg/L on 10 March. Sorry I can't seem to post two sets of results here but preciously my MCH and MCV were also high (and high in every blood test)

I would be very grateful if anyone can comment. I do get a lot of breathlessness, weak and painful muscles and fatigue. I also have unmedicated autoimmune disease and positive ANA antibodies.

Many thanks for any comments!

9 Replies


The exclamation mark next to where it says Full Blood Count - FBC suggests that the lab felt some of the results were significant.

MCH 34.6 (ref range 27 -32 pg)

MCV 98.8 (ref range 80 - 100 fL)

MCH is above the range and MCV is close to top of the range.

High MCV and high MCH can be associated with B12 deficiency and Folate deficiency.

Low iron can lead to small red blood cells(microcytosis). Low B12 and/or low folate can lead to enlarged red blood cells (macrocytosis). A person with both low iron and low B12/low folate may appear to have a normal MCV because the effects of low iron on red blood cells can mask those of low B12/low folate.




"I had severe megoblastic anaemia in my 20's (now late 40's)"

What did Gps think caused megablastic anaemia in your 20s? Did you receive any treatment for it?

One of the possible causes of megablastic anaemia is PA (Pernicious Anaemia). PA requires lifelong B12 treatment. There are other possible causes of megablastic anaemia.

PAS (Pernicious Anaemia Society)


PAS tel no +44 (0)1656 769 717

Have you ever got copies of your medical records?

I get copies of all my blood test results. I learnt to do this after being told everything was fine/normal and then finding abnormal or borderline results on the copies.




Who gets PA and B12 deficiency?




Other b12 info

1) Pinned posts on this forum. I found it helpful to read fbirder 's summary of mainly UK B12 documents. link to summary in third pinned post.

2) BMJ B12 article


3) BSH Cobalamin and Folate Guidelines


UK document giving guidance on diagnosis and treatment of B12 deficiency. I read whole document and gave a copy to my GPs.

Flowchart from BSH Cobalamin and Folate guidelines


Flowchart above makes it clear that in UK, people who are symptomatic for B12 deficiency should have an IFA Intrinsic Factor Antibody test and start initial B12 treatment. This applies whether B12 is low or within range.

Also mentions that it is possible to have Antibody Negative PA (PA where IFA test result is negative).

Lists of B12 Deficiency Symptoms

pernicious-anaemia-society.... see PAS checklist

I gave a copy of PAS checklist to my GPs with all my symptoms ticked.



4) B12 Deficiency Info website

Lots of B12 info plus an interesting blog about B12 issues.


5) Martyn Hooper's blog about PA and B12 issues


6) Book "What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper. Martyn Hooper is the chair of the PAS. Book is up to date with current UK B12 guidelines. I gave a copy to my GPs.

He has written two other books about PA and B12 Deficiency. I also found his book "Living with Pernicious Anaemia and Vitamin B12 Deficiency" helpful because I could recognise aspects of my experience in some of the case histories. It was like reading about myself...made me cry...

7) Book "Could It Be B12; An Epidemic of MIsdiagnoses" by Sally Pacholok and JJ. Stuart (USA authors)

Very comprehensive book about B12 deficiency with lots of case studies.

8) B12d.org


9) UK B12 treatment


Info also in BSH Cobalamin and folate guidelines about a quarter through document.

"My folate is 19.9 ! My B12 was 399 mg/L on 10 March"

I was highly symptomatic for B12 deficiency with results in the 300s and 400s.

Unhappy with treatment?

Link about writing letters to GP about B12 deficiency. Point 5 is about being symptomatic with normal range results.




HDA patient care trust

UK charity that offers free second opinions on medical diagnoses and treatment.


I am not medically trained, just someone who has spent years trying to find the reasons for ill health.

1 like

Thank you so much Sleepybunny for all this amazing information and advice. I am sitting here reading this bit feeling so weak, short of breath and battling mouth ulcers again. I forgot to say that a few years ago my ferritin dropped to 3 and I struggle to maintain a decent level over 11 or 12 most of the time. After a year is Ferrous Fumerate is has reached the grand figure of 29 ! I will definitely investigate the B12 further. I was never given a reason for the megoblastic anaemia but I was quite thin then, drinking at uni so I think they put it down to that. I was so ill and my skin turned yellow and I could barely move! It was awful. Thanks so much once again 😊!


Hi Elsa,

I'd urge you contact the PAS soon.

PAS tel no +44 (0)1656 769 717

There is an answerphone so messages can be left, may take a few days to get a response.

Untreated or inadequately treated B12 deficiency can lead to permanent neurological damage.

"I was never given a reason for the megoblastic anaemia"

Did they carry out an IFA test (Intrinsic Factor Antibody)?

If you get a complete set of medical records there may be something from this part of your medical history in the records..will cost about £50.

Some UK GP surgeries have online access to a summary record but this is only a summary and may not have all the medical info wanted.

I have learnt that in order to get answers people often have to be pro-active and polite but assertive which is a tall order if you have brain that doesn't work properly.

I believe that if I had accepted what my GPs had said eg it's not B12 despite me having numerous typical symptoms and some blood results suggestive of B12 deficiency, I would probably be showing signs of dementia and severe neurological damage. I learnt a hard life lesson in that sometimes the only person who is going to help is yourself.

I hope you have someone kind and supportive who can accompany you to appts. Even better if they have read up about B12 deficiency as sadly some GPs are not as well -informed as they could be about B12 deficiency.

Mouth ulcers, change in skin colour, fatigue, breathlessness, muscle pain, weakness can be found on lists of B12 deficiency symptoms. These symptoms can occur in other medical conditions as well.

B12 deficiency can sometimes be misdiagnosed as another condition..see list below.


What to do next if you suspect B12 deficiency?


There are other conditions that may have similar symptoms. You mention positive ANA antibodies.

Has GP excluded conditions such as ...

Thyroid problems?


Coeliac disease?




Hughes syndrome?


Good luck with getting answers.

1 like

Thank you so much Sleepybunny. I will definitely get my medical records and ring the PAS (thank you for those contact details). I have Hashimotos (antibodies over 1,000). I have been specifically tested for Lupus and Sjorgens and thank goodness tested negative. No reason for my raised ANA and probably thyroid! I will definitely push for a follow up appt with the GP and get tested for that intrinsic antibody. I have had thyrotoxicosis a few months after my daughter was born. She is now 21. You have really inspired me to take this further and not continue to live with all these awful symptoms. Thank you so much!

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More on Hughes Syndrome

It's also called antiphospholipid syndrome (APS) and I think informally called sticky blood syndrome.



More on lupus.

With positive ANA results did you have other screening tests for lupus?


Coeliac disease

It can lead to B12 deficiency as it can affect the gut and therefore lead to absorption difficulties.

It is possible to have Coeliac disease even if basic Coeliac antibody test is negative, people who have IgA (an immunoglobulin) deficiency may need alternative tests for Coeliac disease.....see link in post above.

Medical Records

I believe the only reason for a GP to refuse access to medical records/blood test results etc is if they feel that to give a person access could cause them harm.

If you find anything in records that you feel is incorrect, my understanding is that they don't have to remove it but you can ask for your own note to be inserted in the records.

It can be very illuminating to see what has been written in the past.

In my opinion it's a lot more difficult to get hold of records from hospitals. It may involve a lot of form filling and a visit to hospital records office.

"definitely push for a follow up appt with the GP and get tested for that intrinsic antibody"

Are you currently taking any B12 supplements? Taking B12 supplements without a diagnosis of B12 deficiency can make it extremely difficult to get a diagnosis.


1 like

Hi Sleepybunny. Thank you so much for your further advice. I have had a number of celiac tests but all came back negative although the latter ones were all done when I was gluten free so fairly useless! I also had a gastroscope when my ferritin dropped to 3 and they tested for celiac. However years earlier a naturopath using a vega machine found gluten intolerance. I have also had specific Lupus testing earlier this year due to raised ANA but it came back negative. Last year I had a suspected adrenal tumour from urine samples, super ventricular tachycardia and a body scan but a CT scan didn't show anything. I am a bit of a medical disaster with a childhood of orthopaedic surgery to lengthen my leg! I will definitely look up Hughes syndrome and really push the GP to investigate further. You have been so helpful as I have felt so alone with my symptoms and although my family are supportive they can't take away my awful symptoms! That's good that you pursued your health so successfully and can now pass on your knowledge ! Thank you.


"with a childhood of orthopaedic surgery"

If you've had surgery recently or more than once in your life you might be interested in this link about nitrous oxide. Nitrous oxide is in "gas and air" mix which is sometimes used in anaesthesia.

Nitrous oxide can inactivate B12 in body.


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Thank you Sleepybunny. I had 5 operations by the time I was 16 and spent a year in hospital when I was 10 having my leg lengthening (and 3 anaesthetics) and constant infection where my pins were. I basically barely ate any food and lived on antibiotics. I have also had several ops in my adult life. I was always sickly as a child and it seemed unusual to get such sever e megoblastic anaemia in my early 20's. I recently started the B12 Boost spray on my tongue but will stop that after a week so that I can be accurately tested. Thank you so much and I will also look into the Lupus aspect!


"I recently started the B12 Boost spray on my tongue but will stop that after a week so that I can be accurately tested."

Any B12 supplementation prior to tests may affect results.



There's a chapter in the "Could it Be B12" book where they discuss the effects of nitrous oxide.

Heart rending stories...In my case I believe part of my problems were due to long exposure to nitrous oxide during a difficult labour.

I was so naive and uninformed and did not understand that long exposure to nitrous oxide could have serious affects. I'd have tried to do without pain relief if Ihad known.

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