Hi and thanks for this query.
I am so sorry to hear about your battle with polycythemia
The normal value is set to reflect a normal blood level in the general population, This is often around 45. 46 sounds a reasonable value and i don't understand why they had to change it and more so because you were feeling good then.
What i will suggest is that you talk with your doctor and ask him upfront why it was changed and what were the reasons behind it, It could have been a simple machine error and not intentional. So before pushing further, make sure it was intentional. Also, propose they try the previous upper limit of 46 and see what the extra benefit are.
Hope you find this helpful. Feel free to return to s with more questions. I wish you well.
Dr. Ditah, MD