Early Emphysema in Smokers Detected by Blood Test

A blood test that could detect early signs of emphysema before symptoms occur would warn smokers about the impending development of this untreatable disease.

The new test measures particles that are shed by capillaries that surround alveoli in lungs. These particles are debris shed by ongoing injury to the alveoli that eventually results in devastation of the sacs and the "Swiss cheese" appearance of the lungs.

The study team was lead by Dr. Ronald G. Crystal, chairman and professor of genetic medicine and the Bruce Webster Professor of Internal Medicine at Weill Cornell Medical College and chief of the Division of Pulmonary and Critical Care Medicine at NewYork-Presbyterian Hospital/Weill Cornell Medical Center (New York, NY, USA). Prof. Crystal and his colleagues reasoned that as capillaries surrounding the air sacs are being injured, the debris would be carried out by the blood supply and could potentially be quantified as a disease biomarker. So they looked for evidence of endothelial microparticles (EMP).

They studied three groups of people: healthy nonsmokers, healthy smokers, and smokers with early evidence of lung destruction. All study participants underwent two pulmonary function tests--spirometry, which measures the volume and speed of air as it is inhaled and exhaled from the lungs, and DLCO, the only lung function test available today that can detect emphysema in patients. It uses a machine that measures the ability of gases to diffuse across the alveolar-capillary membrane. EMPs were assessed for a specific enzyme that occurs primarily in pulmonary vessels.

There was a 95% positive correlation between elevated EMPs in the blood and an abnormal DLCO test result, meaning that the blood test detected nearly all verified cases of early emphysema in participants.

DLCO, which must be administered by a pulmonologist, is most often used to confirm a suspicion of emphysema. By contrast, the EMP blood test is designed to be a simple, low-cost screening tool that can pick up development of emphysema in individuals who show no signs of the disorder.

Further studies of the EMP test in larger groups of participants are being carried out in order to validate the initial findings.

The findings were published in the March 11, 2011, online edition of the American Journal of Respiratory and Critical Care Medicine.

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NewYork-Presbyterian Hospital/Weill Cornell Medical Center