Pernicious Anaemia Society

B12 excess question


I'm hypothyroid and I was feeling tired all the time. So I started to supplement once a day, with 1200mcg of Jarrows Methyl B12 (5000mg tab quartered) a day for about 6 months as well as Jarrows B complex (120mcg Vit B12) as well.

I took a blood test (Myrios).

Vit B12 Result was 1004 pmol/L Range 141 - 489

serum Folate 42.3 nmol/L range 10.4 - 42.4

Is this too high? how long does it take to come down if needs too.


1 Reply

Relax, would not worry if I were you. I supplement B12 and monitor (serum) B12 by Myrios, recent results >1400 pmol/l. Feel just GREAT, no more fissured tongue, exhaustion, or 27 other symptoms I had at 167ng/l (180-800ng/l). Treatment was refused, even told "We have many patients with your levels." God help those people, for these GPs certainly won't, so the DIY route, for me, was mandatory

Divide your pmol/l result, and the given range, by 0.738 to get usual NHS ng/l.

When B12 injections are given for PA doctors do not aim for any particular range, just aim to raise the B12 level. Some PAs tested after injection have serum B12 levels of around 2000 ng/l, ng/l being the usual NHS measurement unit.

Any excess would be excreted by body via kidneys, I understand. Personally, from my experience and symptoms monitoring I am convinced we all have different levels of B12 at which we feel OK and I am also convinced the NHS top of range is much, much too low.

You might like to read "Could it be B12?" by Sally Pacholok and Jeffrey Stuart, and "Pernicious anaemia: the forgotten illness" by Martyn Hooper, (founder of the PA society) and the research by Professors David Smith and Hilda Refsum. Very illuminating.


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