My special needs son had an appointment with a new Endo this morning and hopefully this could be a good relationship. We were talking about my son's level of B12 and I mentioned that someone on this forum had said that there was evidence that T4 was not converted to T3 unless your B12 was over 500. He said he would be interested to see this information as he had not been informed of this, and would I please send him this with a quote as to where it came from. I have been looking for the past couple of hours and cannot find who sent in this information. Can anyone help me and possibly give me a website for this. Also, if anyone has any other information that I could slip in, that would be good as I think he is fairly amenable to new information. He did concede that B12 was very important to conversion. We also talked about prescription drug depletion and I will also enclose the list posted by hamster yesterday - thank you hamster. Janet.