There are many ways in which cancer can cause fatigue. The growth of a tumor, in general, can be taxing for your body. Other symptoms of cancer such as shortness of breath, anemia, pain, or a decreased level of oxygen in your blood (hypoxia) can cause fatigue.
A pulmonary function test may take 30 to 60 minutes to complete. This will vary according to the amount of trials necessary for you to get repeatable test results.
Pulmonary function tests are done to: 1  Diagnose certain types of lung disease (such as asthma, bronchitis, and emphysema). 2  Find the cause of shortness of breath. 3  Measure whether exposure to chemicals at work affects lung function. 4  Check lung function before someone has surgery.ormal results are expressed as a percentage. A value is usually considered abnormal if it is less than 80% of your predicted value. Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.