When i was diagnosed with copd i had 23%. how is it posslbe that i now have 50%?

Possibilities...: It is possible that when you were first diagnosed, there was also a component of reversible bronchospasm present. Once that reversible component reversed, either on its own or with treatment, your lung function increased to the 50%. Another possibility is that you were still smoking at the time of the initial test and you have since quit, thus increasing your lung function! good news!