Chronic obstructive pulmonary disease (COPD) is a chronic disease of the lungs that develops when a person has been exposed for a long period of time to lung irritants. Smoking is the main cause of COPD. Other causes include exposure to second-hand smoke, chemical fumes, air pollution, dust, or having the genetic disorder alpha-1-antitrypsin (AAT) deficiency.

How is COPD diagnosed?

Typically, COPD is diagnosed based on an evaluation of symptoms and a complete health history of the person. The doctor usually asks for specific tests to find out whether another condition (e.g., asthma or heart failure) is causing symptoms like wheezing, coughing, and shortness of breath.

Tests may include:

  • Lung function tests. The main test for COPD is spirometry, a painless tests in which the machine (spirometer) measures how much air you can blow into a mouthpiece in one second, and in six or more seconds. The advantage of this test is that it can detect COPD before symptoms are evident, and it can track the progression of the disease.
  • Arterial blood gas test. This test uses a blood sample to measure the oxygen level in the blood, which is an indication of how well the lungs are moving oxygen into the bloodstream and how well carbon dioxide (waste gas) is being removed. The results help to determine the severity of COPD and whether a person needs oxygen therapy (treatment that provides extra oxygen through nasal prongs, a mask, or breathing tube).
  • Chest X-ray and chest CT scan. Both tests create pictures of inside the chest (lungs, heart and blood vessels). A chest X-ray is taken by an X-ray machine, while you stand and hold your breath. In the chest CT scan, you lie still on a table that will slide into the scanner. The machine takes many detailed pictures, which a computer combines into a 3-D image. Sometimes a contrast dye may be injected in your veins before this test, to highlight certain areas inside your chest. Both tests are used to diagnose COPD or to determine whether another condition (e.g., asthma or heart failure) is causing the symptoms.
  • Laboratory tests. The genetic disorder known as AAT deficiency may also be a cause of COPD. AAT is a protein produced in the liver and protects lungs and liver from damage. In the lungs, the disorder can lead to emphysema (which involves damage to the air sacs, causing a poorer gas exchange in the lungs) and a condition frequently tied to COPD.


COPD News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.



American Lung Association

COPD Foundation

National Heart, Lung and Blood Institute