Hi. A few weeks ago I started to develop neurological symptoms (nominal aphasia, balance problems, inability to concentrate/focus, short term memory problems etc.) on top of a whole range of other symptoms I have been experiencing for some time. These include pins and needles in my hands and feet which I have had for a number of years and now realise are also neurological symptoms.
I have autoimmune thyroiditis which is being treated with levothyroxine and have also been diagnosed with fibromyalgia. My GP has consistently put my symptoms down to these two other conditions but the onset of new symptoms prompted me to ask her to check my B12 levels as well as my thyroid function. The B12 result came back as 400pg/mL - no action required. (I had had a B12 test twice before - one came in at at 300 and one at 400). Having done some research, I decided to begin self-treating and have been a taking a high dose methylcobalamin sublingual spray for over a month now. There has been a significant improvement in all of the neurological symptoms except the paresthesias over the last month and I am generally feeling a bit better. My GP knows about all of this and seemed bemused given that my B12 level is 'in the normal range'! She was happy for me to continue self-treating and did not offer any further treatment or tests.
My question is what dosage of methylcobalamin should I be taking? I started with 1200mcg a day and have recently increased to 2000mcg a day. I am keen to get my B12 levels up to the top end of the normal range as there is evidence that this can help with absorption of levothyroxine and I am not happy with my TSH level which is currently 3.2 (too high for me but again in the so-called normal range) Also given that I do still have neurological symptoms as well as a range of other symptoms which could be attributed to B12 deficiency , should I be pressing for B12 injections instead as per the NICE/BNF guidelines?