Not exactly Thyroid related, but I was interested to read this in Dr Malcolm Kendrick's blog on how B12 ranges were arrived at:
"The agreed Vitamin B12 levels, for example, were based on seven people, over sixty years ago, and remain unchanged to this day. All seven had pernicious anaemia (caused by vitamin B12 deficiency)."
Unfortunately that where today's GPs, endocrinologists take their lead from!
Ptetty shocking. That is why symptoms are more important than ranges - but hey that would not suit Big Pharma. It would also demand good diagnostic skills at GP level 😊
this came up recently on PAS forum.
Personally very sceptical about the claim. The subcommittee that looks at setting RDA for the EFSA (European Food Standards Agency) reviews the recommendations every few year in an open invitation for evidence - the last review was in 2015.
Whilst I haven't actually been able to find the outcome of the last review on the website, or the document that put together the original recommendations this document - p45-46 discusses nutritional requirements relating to B12 in normal population and the various absorption problems that can occur
Strange B12 Ranges
ferritin dropping but b12 over range
B12 range - Dutch B12 deficiency organisation
B12 1359ng/L (normal range 197 -770)
Folate below range, low B12, second Covid vaccine on Monday
