Hi Alan and welcome,
Norman Thomas, a PAS trustee, and I have been trying for the last several years to confirm that Japan really does have the reference range of 500 - 1300. It is printed in research articles, always with references to another research article. When we traced all of the research articles it went back to one such article that stated this with no supporting information.
Norman and I both have contacted the Japanese Government Department of Health with no success. To date, neither Norman nor I can find the research article or the actual study that gives their reference range as being 500 - 1300.
My opinion is that it is a myth based on the first research article that stated this without citing any study or supporting information. The article below appears to confirm this.
The article below is Japanese and they use a cut off point as being 200 pg/ml which is 147 pmol/L.
http://plaza.umin.ac.jp/j-jabs/31/ft.31.291.pdfRegards,
Pat
I am a support person for my daughter who was diagnosed with PA and Folate Anaemia in 1994, at the age of 27. Another daughter diagnosed with Hashimotos 2010 but she doesn't have PA.