One of the consequences of the medical scrutiny I've been subjected to this year is that very high levels of B12 have been detected in my blood. I understand that "normal" range is something like 100 - 400 ng/l and mine has consistently been up around 1550 - 1600 ! This can be a marker for blood disorders like leukemia, so I was packed off for a liver/spleen scan and my rheumatologist and his colleague haematologist were consulted. My other blood markers are normal and nobody seems overly concerned, apparently this is being considered a by-product of my inflammatory arthritis. I can find no other examples of this being the case, so would really be interested to hear of anyone else having the same issue.
Just for the record, we looked at my diet and eradicated everything that could have been a contributory factor. It made hardly any difference.