Diagnosis of COPD

Spirometry: The Primary Tool For Making a COPD Diagnosis

CT Scan
CT Scan of the Chest. Photo © istockphoto.com user Joel Johndro

After reading this article, your will have an opportunity to share about what you've learned since your initial diagnosis of COPD.

According to the Global Initiative for Obstructive Lung Disease (GOLD), a diagnosis of COPD should be considered in any patient who has shortness of breath, a long-term cough or sputum production and/or a history of exposure to COPD risk factors.

Spirometry: The Primary Diagnostic Tool in COPD

A spirometry test is required to make a clinical diagnosis of COPD.

Persistent airflow limitation, or COPD, is confirmed when test results show an FEV1/FVC of less than 0.70 after a patient uses a bronchodilator.

Additional Studies That Support a COPD Diagnosis

Although spirometry is the primary diagnostic tool in COPD, your doctor may perform any or all of the following investigational studies during her initial assessment to support a COPD diagnosis:

History and Physical

If your doctor suspects COPD, your assessment will start with a detailed look into your history. This should include reviewing:

  • your current and past exposure to risk factors such as smoking, secondhand smoke, air pollution and/or occupational exposure to dust, gasses, and chemicals.
  • your medical history, especially as it pertains to current respiratory disorders like asthma, allergies or sinusitis and/or respiratory illnesses during early childhood.
  • prior hospitalizations, especially if they were associated with respiratory illnesses.
  • if anyone in your family has ever had COPD or any other chronic lung disease.
  • if you have other existing medical conditions, such as heart disease or osteoporosis, which may further impact a diagnosis of COPD.
  • the pattern of your symptom development, including when your symptoms started and how long you waited before seeking medical attention.
  • the impact of the disease on your everyday life; for example if your symptoms have caused you to miss work, limit your regular activities or to feel depressed or anxious.

Your doctor should also perform a thorough physical examination that may include:

  • Taking your temperature, pulse, breaths per minute, pulse and blood pressure
  • Listening to your heart and lungs with a stethoscope
  • Examining your ears, nose, eyes and throat for signs of infection
  • Examining your fingers for signs of cyanosis and clubbing
  • Assessing for signs of swelling in your legs, ankles, and feet or other parts of your body
  • Evaluating the veins in your neck to assess for complications of COPD such as cor pulmonale

Additional Pulmonary Functions Tests (PFTs)

In addition to spirometry, there are two other pulmonary function tests important when evaluating lung function in COPD: lung diffusion tests and body plethysmography. These tests measure the diffusing capacity of the lungs for carbon monoxide and the volume of air in the lungs at different stages of breathing, respectively.

Chest X-ray

A chest x-ray alone does not establish a diagnosis of COPD. Your doctor may order one initially however, to rule out other reasons for your symptoms or to confirm the presence of an existing comorbid condition.

A chest x-ray may also be used periodically throughout your treatment to monitor your progress.

Computerized Tomography (CT) Scan

Although a CT is not routinely recommended when making a diagnosis of COPD, your doctor may order one when it’s indicated (infection is not resolving, change of symptoms, consideration for surgery etc.) While a chest X-ray shows larger areas of density in the lungs, a CT scan is more definitive, showing fine details that a chest X-ray does not. Sometimes, prior to a CT scan, material called contrast is injected into the vein. This allows your doctor to see the abnormalities in your lungs more clearly.

Complete Blood Count

A complete blood count (CBC) will alert your doctor to an infection as well as ​telling him, among other things, how much hemoglobin is present in your blood. Hemoglobin is the iron-containing pigment in your blood that carries the oxygen from your lungs to the rest of your body.

Arterial Blood Gases

In COPD, the amount of air that you breathe into and out of your lungs is impaired. Arterial blood gasses (ABGs) measure the oxygen and carbon dioxide levels in your blood and determine your body's pH and sodium bicarbonate levels. ABGs are important in forming a diagnosis of COPD as well as in determining the need for and adjusting the flow rate of oxygen therapy.

Pulse Oximetry

Pulse oximetry is a noninvasive method of measuring how well your tissues are being supplied with oxygen. A probe or sensor is normally attached to the finger, forehead, earlobe or bridge of the nose. Pulse oximetry can be continuous or intermittent. A measurement of 95% to 100% is considered normal. Along with ABGs, measuring your oxygen saturation level by way of pulse oximetry helps your doctor assess your need for oxygen therapy.

Alpha-1-Antitrypsin Deficiency Screening

If you live in an area where there is a high prevalence of Alpha-1-antitrypsin (AAT) deficiency, the World Health Organization recommends that you be tested for this disorder. AAT deficiency is a genetic condition that can lead to COPD. Being diagnosed at a relatively young age (less than 45 years old) should also alert doctors to the possibility that AAT deficiency is the underlying cause of your COPD. Treatment for COPD that is caused by AAT deficiency includes augmentation therapy.


The Global Initiative for Obstructive Lung Disease. Global Strategy for the Diagnosis, Management and Prevention of COPD. Updated 2011. Available from goldcopd.org.