Navigate Up

Seniors Center - A-Z Index

#
Q
Y
Z

Print This Page

Lung diffusion testing

Lung diffusion testing measures how well the lungs exchange gases. This is an important part of lung testing , because the major function of the lungs is to allow oxygen to "diffuse" or pass into the blood from the lungs, and to allow carbon dioxide to "diffuse" from the blood into the lungs.

Alternative Names

Diffusing capacity; DLCO test

How the Test is Performed

You breathe in (inhale) air containing a very small amount of a tracer gas, such as carbon monoxide . You hold your breath for 10 seconds, then rapidly blow it out (exhale). The exhaled gas is tested to determine how much of the tracer gas was absorbed during the breath.

How to Prepare for the Test

  • Do not eat a heavy meal before the test.
  • Do not smoke for at least 4 - 6 hours before the test.
  • If you use a bronchodilator or inhaler medications, ask your health care provider whether or not you can use them before the test.

How the Test will Feel

The mouthpiece fits tightly around your mouth. Clips are put on your nose.

Why the Test is Performed

The test is used to diagnose certain lung diseases, and to monitor the status of people with established lung disease. Repeatedly measuring the diffusing capacity can help determine whether the disease is improving or getting worse.

Normal Results

Normal test results depend on a person's:

  • Age
  • Gender
  • Height
  • Hemoglobin (the protein in red blood cells that carries oxygen) level

What Abnormal Results Mean

Abnormal results mean that gases do not move normally across the lung tissues into the blood vessels of the lung. This may be due to lung diseases such as:

Risks

There are no significant risks.

Considerations

Other pulmonary function tests may be done together with this test.

References

Hegewald MJ, Crapo RO. Pulmonary function testing. In: Mason RJ, Broaddus VC, Martin TR, et al., eds. Murray and Nadel's Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Elsevier Saunders; 2010:chap 24.

Reynolds HY. Respiratory structure and function: mechanisms and testing. In: Goldman L, Schafter AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 85.

Updated: 12/3/2013

Denis Hadjiliadis, MD, Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.


©  UPMC | Affiliated with the University of Pittsburgh Schools of the Health Sciences
Supplemental content provided by A.D.A.M. Health Solutions. All rights reserved.

For help in finding a doctor or health service that suits your needs, call the UPMC Referral Service at 412-647-UPMC (8762) or 1-800-533-UPMC (8762). Select option 1.

UPMC is an equal opportunity employer. UPMC policy prohibits discrimination or harassment on the basis of race, color, religion, ancestry, national origin, age, sex, genetics, sexual orientation, marital status, familial status, disability, veteran status, or any other legally protected group status. Further, UPMC will continue to support and promote equal employment opportunity, human dignity, and racial, ethnic, and cultural diversity. This policy applies to admissions, employment, and access to and treatment in UPMC programs and activities. This commitment is made by UPMC in accordance with federal, state, and/or local laws and regulations.

Medical information made available on UPMC.com is not intended to be used as a substitute for professional medical advice, diagnosis, or treatment. You should not rely entirely on this information for your health care needs. Ask your own doctor or health care provider any specific medical questions that you have. Further, UPMC.com is not a tool to be used in the case of an emergency. If an emergency arises, you should seek appropriate emergency medical services.

For UPMC Mercy Patients: As a Catholic hospital, UPMC Mercy abides by the Ethical and Religious Directives for Catholic Health Care Services, as determined by the United States Conference of Catholic Bishops. As such, UPMC Mercy neither endorses nor provides medical practices and/or procedures that contradict the moral teachings of the Roman Catholic Church.

© UPMC
Pittsburgh, PA, USA UPMC.com