This is a huge step forward in getting B12 deficiency diagnosed and treated, although far from perfect. If you have any thought in your head that you might be B12 deficient please read this document with a fine toothcomb and bring to your GP.
DO NOT SUPPLEMENT FIRST!
Skip to Algorithm 1 for a diagnosis summary flowchart. Note that if you have symptoms and a normal serum B12, treatment should be commenced regardless, whilst second line tests are done - anti-IFAbs, Active B12, MMA, Homocysteine.
Also note that you can have negative anti-IFabs PA, a clinical response to treatment is enough reason to continue treatment FOR LIFE.
And even more important, even if there's absolutely no biological evidence of deficiency (i.e. ALL the tests are "normal") the doc has the option to continue treatment if there has been a good clinical response.
Hopefully now it becomes more clear why I am always saying please don't place any importance on the serum B12 test.
Have to pop out now, will read through the whole thing later and highlight anything else I think might help us.