Hi, I have not posted on here before, although I have on the thyroid site. My question is how long do I need to be off B12 supplements before I can be tested for PA. When tested in September my level was 270, my GP didnt seem very interested and said I could buy supplements over the counter if I wished. I bought Jarrow B12 off the internet and took them for a few months, my levels went up to 750. When I saw a different GP he said I should of been tested for PA, but as I had been supplementing they couldnt do the test. Its all very confusing. I would be grateful for any help.