Pernicious Anaemia Society
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B12 150 or 190 lower limit?

My B12 at 178 is way above the lower limit? Or is it?

Hi there. I asked the Doctor to check my B12 because of some symptoms I was having, eg tiredness, joint pain, mostly knees, and lower back, involuntary biting of tongue, and inside cheeks (really weird), and my mother and father were both diagnosed with Pernicious Anemia.

I have been to and fro ing with these symptoms and others for years never knowing anything about B12

I do eat fish, eggs fortified soya milk and eat well, but I am unable to eat gluten, or milk or milk products or oats or red meat without terrible gastric problems.

My b12 came back at 178 though I had been supplementing with a b complex tablet (which contained wheat) until a couple of weeks before the blood test. I stopped the tablets as the wheat began to start my gastric problems off again.

The Doctor (I live in Wales) said the lower limit was 150 upper 900, and my 178 was fine. Yet I have read that in England it is 190 - 900. As I had taken supplements he suggested I continue for 3 months and be retested.

I thought there was further tests that could be done to ascertain whether I had P A or not? Something to do with intrinsic factor?

I have since changed surgery and saw the nurse this morning, who said that if I thought my B12 was low at 178 I should move to England as here in Wales it is far above the lower limit!

I now have an appointment with a doctor for next week. Since my blood test 13 December 2017 I have been supplementing with a spray and sublingual b12 and felt better though it is a slow process.

Should I be having injections?

Your opinion would be very welcome.


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7 Replies

The normal range depends on the exact test procedure and therefore it depends on the lab that did the test. The test results give the expected normal range so arrange with your doctor to see your test results. You have the legal right to see them and (often for a small charge) have a copy.

Though at the same time B12 serum results are not the full picture and if you are at the lower end of the range your symptoms should be taken into account.

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there are also two units for measuring serum B12, ng/L and pmol/L - they have different ranges associated with them - pmol/L being lower and starting around 140, ng/L tends to start around 180.

regardless of that serum B12 isn't a gold standard test and normal range will miss 25% of people who are b12 deficient if taken as a single measure. symptoms are important but it also needs to be born in mind that although macrocytosis (larger rounder red blood cells is a classic symptom of B12 deficiency) it also isn't present in 25% of people first presenting with B12 deficiency.

tests to clarify if you have a B12 deficiency would be either homocysteine or MMA - they are also raised by other factors (folate deficiency in the case of homocysteine) so need to be done in a context that rules out other factors.

IFA is a test for PA as a specific cause of B12 deficiency - there are others but the symptoms of PA are the symptoms of the B12 deficiency it causes and IFA isn't a particularly good test for ruling out PA as the cause of a deficiency as it gives false negatives 40-60% of the time depending on the exact test method.

If you have problems with wheat - then would be good to get checked for coeliacs as this can also affect B12 absorption. You have to be taking gluten in your diet for this test to be worth doing.


Hi thank you for replying. I have had a celiac test twice! Both times after being totally off gluten ( not even malt vinegar on my chips) for longer than two years or more. Results were negative.

My b12 serum result was 178 ng/l the MCV was 89fL range 80-100 platelet count 169x10*9/L range 130-400x10*9/L total white cell count is 3.2x10*9/L range 4.00-11.00x10*9/L my serum folate was 17.4ug/l (I eat a lot of greens since being told I was beginning to show signs of macular degeneration by optician two years ago)

Again thank you all.


if you had been off gluten for two years then the result of the coeliacs test can't be taken as conclusive - a negative result is the result you would expect whether or not you were coeliacs

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I sort of knew that, but because a doctor hasn't seen a result saying I am celiac, they tend to not believe me when I say that I cannot eat gluten. One docter did offer a test again if I would eat gluten again, but I declined, and as he said, the only "cure" is to keep off gluten!

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If you're in UK,

NICE guidelines on Coleiac Disease (2015 version) suggest that a person with suspected Coeliac disease who doesn't want to start eating gluten again could be referred to a gastrointestinal specialist.

PAS website


PAS tel no +44 (0)1656 769717 answerphone

B12 Deficiency Info website

Link about What To Do Next if b12 deficiency is suspected

Blog posts about variations in B12 ref range across UK

B12 books I found useful

"What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Martyn Hooper is the chair of PAS (Pernicious Anaemia Society) based in Wales, UK.

"Living With Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper

Has several case studies.

" Could It Be B12?: An Epidemic of Misdiagnoses " by Sally Pacholok and JJ. Stuart (USA authors)

Very comprehensive with lots of case studies.

Lots more B12 info in pinned posts on this forum. I've written some very detailed replies recently. Might be worth searching on forum for them.

Have you had your Vitamin D levels checked?

Tests for Thyroid problems?

UK b12 documents/articles

BSH Cobalamin and Folate Guidelines

Flowchart from BSH Cobalamin and Folate Guidelines

Flowchart makes it clear that people who are symptomatic for B12 deficiency should have an IFA test and start initial B12 treatment whatever their B12 level.

BMJ B12 article

Emphasises need to treat symptomatic patients even if B12 level is normal range.



B12 Deficiency Symptoms

pernicious-anaemia-society.... (may need to be member)

Risk factors for PA and B12 Deficiency


Unhappy with treatment?

Letters to GPs about B12 deficiency

CAB NHS Complaints

HDA patient care trust

I am not medically trained.


Hi jointpain also ask to have your Folate level checked.


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