Pernicious Anaemia Society
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Symptoms with high b12 serum

Does anyone still experience symptoms when their serum b12 is sitting at around 900pg/ml?

Mines been consistently high since I began supplimenting b12 sublingually but I still feel wiped out.

My last few blood tests have all shown my levels almost at the top of the range.

My consultant said he thinks the low b12 may of been a red herring.

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Yes. My serum levels are always above 6000. I keep thinking that my symptoms can't be due to B12, so I go without a jab. But after 10 days without I just cannot do anything.

My MMA and hCys are, on several occasions, normal.


That's reassuring as I'm about to start a trial of injections but after reading about causing functional issues by supplimenting I had concerns and the consultant threw a spanner by saying he felt b12 was a red herring.

I've felt bad since 2008 and incidentally my first low b12 test is 2012. In 2008 it was 287.

They've only just agreed to treat it.

I've supplemented since November but feel worse in many aspects although this all starts back in July with light aversion and migraine.

I'm crawling through Tesco and the noise levels are crippling.

I've never been like this until these last few months.


Hi Steap. Unfortunately, serum B12 levels (and the reference ranges used to measure those levels) cannot in any way be used as an indicator of the efficacy of treatment.

Once B12 treatment commences the testing of serum B12 levels is not recommended - unless checking for continued low levels - in which case more B12 is needed.

All the guidelines state this - but unfortunately many medics (as you know) are completely unaware of this.

I think we've had the neurologist B12 'red herring' discussion before - the neurologist (like your GP) is looking at your current serum B12 level - can't be a B12 problem - levels are okay. Wrong.

My neurologist (who knew little about B12 deficency) was of the same opinion.

If I recall rightly, you had a proven B12 deficency for four years, which your GP failed to treat, and because you've now taken supplements and can't replicate the required deficenct or low levels, your GP now refuses to consider that B12 was/is an issue. It appears that you neurologist is making the same mistake. Ridiculous.

The only way to assess the effectiveness of B12 treatment, once started, is symptom relief.

Symptom relief and neurological repair can take some time...but it's so difficult to predict because we're all different and so recover and repair at different rates. For those who have been deficent for some time (like you were) recover and repair can take longer. We hear on the forum of people who are still experiencing signs of recover after one year on intensive B12 treatment.

Like fbirder , my serum B12 levels are always high (the lab that does my bloods only measures up to 2000, and mine are always in excess of this) and to keep symptoms at bay, I need to inject every week (occasionally, more often than that).

And MMA and homocysteine normal, so no functional deficency 😄.


P.s. Just noticed your reply above - many people here report that symptoms do appear to get worse when treatment is started - it thought that this is due to the repair process - a bit like the signals suddenly being turned up and the brain having to get used to re-interpreting the new stronger signals...and that this settles down once the brain re-adjusts...but nobody knows for sure.

Grief...B12 deficiency is soooo tricky 😖😄

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The consultant was a gereral physician but he did write to a neurologist for an opinion. It's not about b12 though, it's about something on my spinal cord MRI.

I still don't know what that is yet because the Gp referred me to an orthopaedic surgeon for it and I've not seen him yet.

I also have no idea why he did that as it's on my cord not my bones.

It all does wonders for my anxiety levels.


Surgery just rang. I "don't need loading doses because I'm not clinically deficient", so I'll be getting one injection next Thursday morning then nothing else for a further three months.........

I don't know how I feel about that.

How do I test the theory

Will one injection get my levels up much higher than I've done with the sublinguals. Especially if they're instructing me not to take any additional b12.


fbirder do you have any experience of folate being above range in relation to b12.

My last test is the first time it's been like that but I've not been tested while supplimenting folic acid before.

My centrum has 200mcg in it which is a tiny amount and I've only been on it about four weeks.

Previously my folate was in range.

Interestingly my symptoms except fatigue all kick off last year after being on a vitamin spray that had folic acid in too.

I wonder if that tipped my folate over range too?? I'd stopped it for a while before going to the Gp and getting tests <grasping at straws


Hemotologist Chart Is 300-1000...But Other Specialist Are 300-2000 ...My Levels Are Up To 1400 From Low 300's In August 2016...I Still Have Some Symptom...It Takes Time For The Body To Repair...Though Some Neurological Damage May Be Permanent...B-12 Effects Our Neurologica, Gastroentro & Heart


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