I'm new here and I wanted to ask this community about what I need to ask the endocrinologist when I see him soon. I have been posting over on the Thyroid UK site. In brief, I had been on 150mg levothyroxine for 20 + years with no problems. I had flu in March/April 2016 which sparked a health crisis with neurological symptoms (peripheral neuropathy, pins and needles, burning sensations, headache, nerve pains, twitches in my legs etc). I hade a number of rapid changes of levothyroxine dosage. I have now been on 125mg for the last 4 weeks, bloods being done tomorrow.
I was getting worse and worse until I started supplementing 1000mg sublingual methylcobalamin + a B complex supplement on 2nd July. This had an immediate effect in reducing and eradicating some of the worst symptoms and I have made slow, steady progress to date. I have had quite a lot of nerve damage in my legs. I still get some nerve twitches but they are much reduced.
My GP says I don't have PA because my MCV was 'normal' (88.8 range 77-100). My serum B12 tested at 452ng/L. The widespread advice about supplementing B12 if below 500 informed my decision to start supplementing. I have since read the British Society for Haematology's 2014 Guidelines for the diagnosis and treatment of Cobalamin and Folate disorders, which recommends further tests and trial dosage of hydroxocobalamin when there is a 'strong clinical suspicion of cobalamin deficiency' based on symptoms in cases greater than 200ng/L .
I feel like I have been giving myself a replacement dose of B12 but have never received a 'treatment' dose that addresses the neurological symptoms. Are the intramuscular injections more effective than oral doses? Presumably oral supplementing wouldn't have worked if I had PA? Or could I have been absorbing the B12 via my mouth rather than in the gut? Presumably I should ask the endocrinologist to test for Intrinsic Factor antibodies to rule out PA? (Although I see from the guidelines that patients negative for the IF antibodies 'with no other causes of the deficiency, may still have pernicious anemia').
Any guidance very gratefully received.