I had one lung function test where my FEV1 was 46 and then another test where my FEV1 was 75? Isn't an FEV1 of 75 still considered to be mild COPD? I don't know if I took the first test right, but how can these values be so off? I also have a severely reduced FVC and a very low DLCO. I Had signs of hyperinflation of lungs, but my HRTC scan and Chest X-ray were both completely normal. I really don't know what to make of all of this. I have low oxygen levels at night. My oxygen levels are under 88 all night long. Could you have COPD and a completely normal HRCT scan and chest X-ray? I read somewhere that COPD can be missed on HRCT scan, especially low dose HRCT. Wouldn't hyperinflation show up on a basic X-ray? Also, my FEV1/FEV ration are elevated at 90. Maybe their machines were not calibrated properly? For now I'm going to stop using the inhalers and not even worry about it. My PCP says I do not have COPD because my lungs are clear, but the specialist says I do have it. What do you guys think?