This video is well worth a watch. It's long but please watch the entire video. You may have to pause it come back to it.
Even though it focuses mostly on neurological issues, it applies to blood disorders. B12 deficiency is much more wide spread than we know and it is missed by doctors who rely on just the B12 serum test. The video gave a list of tests to assess B12:
Serum B12
HoloTranscobalamin
Homocysteine
Methylmalonic Acid (MMA)
Unsaturated B12 binding capacity
Some of the things you'll hear in this video are some of the same things people have posted on this site regarding their doctor's attitude to B12. And, it gives you a brief history as to why B12 testing has fallen by the wayside and why B12 deficiency is missed.
Even if this doesn't apply to your specific case, it is well worth watching. I'm sure most will know of someone who could benefit from this knowledge. The one thing that stood out for me was the problem of excess folate masking B12 deficiencies. Especially in pregnant women which can then lead to post pregnancy issues as well as problems for their infant.
http://www.youtube.com/watch?v=BvEiz...ature=youtu.be
Please take the time to watch for you may find some nugget of information that applies to you.