Most people with emphysema are diagnosed after age 45 years, although if you have a faulty gene, you may be diagnosed earlier. Your doctor can diagnose emphysema by talking to you, examining you and doing a breathing test called spirometry, which measures how well your lungs work. They may also arrange: blood tests a chest x-ray a blood test from an artery to check your oxygen levels further breathing tests, called lung function tests a CT scan of your lungs an ECG (electrocardiogram) or echocardiogram to look at your heart