taking your evaluation to a higher level is wise but remember there are many many reasons for a diminished lung capacity. a pulmonologist is the preferred expert in this area.
i have recently been told following some breathing tests that i have a lung capacity of 80%. i am 53 and worried. i can feel a draw for the last 5 years on my left side not painful just strange feeling with light wheeze sometimes. a little more breathless walking or being active and ecg showed ectopic beats which i was told are no harm however my medical consultant told me i have the age predicted lung capacity of a 69 year old woman and i got an awful shock. he is arranging for me to have repeat breathing tests and possibly a ct scan of the lungs.