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Tests are performed in order to diagnose lung diseases, determine their causes (where possible), and evaluate their severity. Many doctors will order blood gasses to evaluate oxygen and carbon dioxide levels, lung or pulmonary function tests (PFTs) to help diagnose and monitor lung function, and chest X-rays and/or CT (computed tomography) scans to look at lung structure. Other testing is performed to help diagnose specific conditions.

Laboratory tests

Lung function tests (pulmonary function tests, PFT)
A few of the more common tests are listed below. 

  • Spirometry – measures the amount and rate of air exhalation as a patient blows out through a tube. It is performed to evaluate narrowed or obstructed airways.
  • Air flow with a peak flow meter – measures the rate of exhalation. Patients with asthma can use this at home to help monitor their condition.
  • Lung volume – measures the quantity of air a person takes into their lungs and how much is left in the lungs after exhalation. It helps evaluate the elasticity of the lungs, the movement of the rib cage and the strength of the muscles associated with respiration.
  • Diffusing capacity measurement – assesses the transfer of oxygen from the lung air sacs to the bloodstream by evaluating how much carbon monoxide is absorbed when a small quantity is inhaled (not enough to harm).

Imaging studies

  • Chest X-ray – looks at the lung structure and chest cavity
  • CT (computed tomography) scan – enables a more detailed evaluation of the lung structure
  • MRI (magnetic resonance imaging) – provides detailed pictures of the organs and vessels in the chest
  • Ultrasound – detects fluid between the pleural membranes
  • Nuclear lung scanning – helps detect pulmonary embolism and, rarely, is used to evaluate the effectiveness of lung cancer treatment
  • Positron emission tomography (PET) scans – helps diagnose lung cancer

Other tests

  • Electrocardiogram (ECG) – looks at heart rhythm, to determine if heart disease may be affecting breathing
  • Sleep studies – help determine whether a person is breathing normally during sleep and are usually performed at special sleep centres

Last Review Date: November 6, 2017