Hi Badra,
I'm not sure what you are trying to ask
Correct me if I am wrong; are you asking if you should take 250ml instead of 500ml per month?
Well, in any case, it all depends on you HB. If you require 500ml according to your weight and physique to keep the HB above 10g/dl, then there is no need to cut down transfusion unless you can tolerate low HB and your doctor advises it!!
Take care, Peace!