This is a big and complex subject and I have much more to do, but I have started a new Anaemia factsheet for you on the clinic site.
So far, I have linked to some of the blog posts on here for you as I’ve written quite a lot on the subject, put a link to the main anaemia test (anemia for our US cousins!) and added some useful info specifically about B12 anaemia/deficiency.
Hope it’s useful.