Can you have early emphysema  with a normal ("unremarkable")pulmonary
function test?
The lungs are hyperinflated. The person has Marfan's disease and is a smoker.

Marfan's syndrome pulmonary manifestations include subpleural blebs,
which are pockets of abnormal
lung tissue that characterize emphysema. In Marfans it is a local
process usually in the apices of the lungs. This may develop abruptly
into a more serious life threatening pneumothorax,a rupture of these
blebs.In tobacco-related emphysema, it's a more diffuse  destruction
of the lungs. Though it takes decades to develop abnormal pulmonary
function tests in smokers , your friend might be wise to quit smoking
now. A CT scan of the chest would be the best test at this time. A
referral to a lung specialist is also recommended after the CT.

Hi jjs,

Pulmonary emphysema is defined as a lung disease characterized by
"abnormal enlargement of the air spaces distal to the terminal,
nonrespiratory bronchiole, accompanied by destructive changes of the
alveolar walls". These lung parenchymal changes are pathognomonic for
emphysema. Detection of such changes during life, however, is
difficult as these findings are MICROSCOPIC changes.

Generally, the diagnosis of emphysema is based on indirect features,
such as clinical examination, pulmonary function tests, and subjective
visual evaluation of computed tomography (CT) scans. These tests are
of limited value in assessing mild to moderate emphysema.

In view of these, "unremarkable" or "normal" test report does NOT rule
out emphysema and the person should be advised to quit smoking, all
the more so in view of Marfan's syndrome.

Hope this is what u r looking for.