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What Do Lung Function Tests Show?

Breathing Tests


Spirometry can show whether you have:

  • A blockage (obstruction) in your airways. This may be a sign of asthma, COPD (chronic obstructive pulmonary disease), or another obstructive lung disorder.
  • Smaller than normal lungs (restriction). This may be a sign of heart failure, pulmonary fibrosis (scarring of the lung tissue), or another restrictive lung disorder.

Lung Volume Measurement

These tests measure how much air your lungs can hold when you breathe in and how much air is left in your lungs when you breathe out. Abnormal test results may show that you have pulmonary fibrosis or a stiff or weak chest wall.

Lung Diffusion Capacity

This test can show a problem with oxygen moving from your lungs into your bloodstream. This might be a sign of loss of lung tissue, emphysema (a type of COPD), or problems with blood flow through the body's arteries.

Tests To Measure Oxygen Level

Pulse oximetry and arterial blood gas tests measure the oxygen level in your blood. These tests show how well your lungs are taking in oxygen and moving it into the bloodstream. A low level of oxygen in the blood might be a sign of a lung or heart disorder.

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Lung Function Tests Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Lung Function Tests, visit

September 17, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.