Is my B12 too low at 353ng/l ?

Just been to GP for blood test results .I have Hashimotos, and had radioactive iodine done to destry my thyroid before full Levo replacement but since my dose was reduced from 125mcg to 100 mcg I now feeling increasingly very tired , cold hands, etc , or wondered if I was now underdosed, or anaemic. However since my haeoglobin result was 135gl could it be something to do with my Vit B 12 level which seems low at 353 ngl,( the parameters for Vit B 12 in the local lab are 200-940 ng/l.) Is it this that is causing my symptons as I understand that Vit B 12 is involved in T 3/ T4 metabolism. Should I be supplementing, with Vit B 12, and if so, by how much? Hope someone can shed some light!

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13 Replies

  • Vitamin B12 is important and like Vitamin D can be deficient. Your B12 is too low and you should aim towards the higher end of the range. You can supplement with B12 but it must be methylcobalamin and not cyanocobalamin. You can purchase from Amazon (link on right-hand column). Sublingual will go directly into your bloodstream which is preferable. The dose you take depends on you and on the bottle it will advise how many to take per day usually with food. Always take supplements four hours apart from thyroid gland medication.

  • The Pernicious Anemia Society is trying to get the reference range changed to being at least 500. They say 400-500- is suspicious. Anything under that should definitely be treated. You might find it helpful to look at that website and also there is a site called Vitamin B12 Deficiency and that also has some excellent resources as well as an assessment sheet of signs and symptoms with an action plan of what to do/

    If you are going to supplement with B12 subliminally you will also need to take a good complex vitamin B tablet as well -this is because the vitamins B's work best together -follate is also important for the uptake of vitamin B12 so check your follate levels.

    Lastly you might want to ask your doc to runs some further tests such as checking your 'intrinsic factor '-this is commonly low or absent in low B12 levels and without it you cannot absorb it through your tummy.

    Lastly as we age -women in partciular become less able to absorb b12 -especially over the age of not saying this is you......but I think it is the reason why I have a problem -and i am not over it must have started early for me!!! he he :) :)

  • I have just realised your GP has reduced your dose of levo. Why? Most probably it is due to your TSH alone. This is wrong. Adjustments shouldn't be necessary and that could be why you are also feeling not too good.

    Get a print-out from the surgery of your blood test and post with the ranges.

  • Hi All

    I am taking B complex which has B1,B2,B3 and 12? Should i continue.

  • What levels of each are in the complex? If your B12 is low or deficient it is unlikely there will be sufficient B12 in the complex to raise it.

  • Hi clutter Thank you. Instead of B3 it should be B6. However i have never been tested for B12 so it was just to boost myself which I feel awful. I bought this from Belgium its "Befact Forte" It doesn't have Lactose. I have appt on 28 I will ask for the test.

  • You need to stop supplementing 4-8 weeks prior to testing for the B12 serum test.

  • Wow Clutter! is this really necessary? I won't be able to stop supplements for 4-8 weeks for my b12, I am too weak without them. I can only go without for a week maximum.

    Do you know how many days/ weeks to stop supplementing iron, b 12, vit d and folate before blood test for iron , vit d and folate?

  • If you can only last a week it sounds like you either don't store b12, you don't have any B12 stores or you can't use the stores.

  • It may be that you have pernicious amaemia and need injections. Sounds like it will be really rough to stop supplementing :(

  • My last b12 level was over 600, I don't think that I am severely deficient, swallowing tons of supplements for me It's the way of making up the energy that is missing from inadequate thyroid hormones level, I don't do well with thyroid meds. Thank you for reply Carolyn

  • If you continue supplementing it won't give an accurate result. Your serum result may show good in range due to the supplementation. You can't OD on B12 so it doesn't matter if it shows high in range. Just tell the phlebotomist to note on the form that you are supplementing.

    I think you need to stop taking iron about a week before testing. Not sure it matters for vitD and folate but don't take them until after your test.

  • Hi Clutter

    Thanks for that info. really helpful.

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