MONDAY, Feb. 25 (HealthDay News) -- A special technique that uses laser light to sample a person's breath can detect molecules that may be markers for a number of diseases, a U.S. study says.

This approach, called cavity-enhanced direct optical frequency comb spectroscopy, may one day help doctors screen patients for diseases such as asthma, cancer, kidney failure and diabetes, according to the team of scientists at JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado at Boulder.

"This technique can give a broad picture of many different molecules in the breath all at once," lead researcher Jun Ye said in a prepared statement.

Optical frequency comb spectroscopy was developed in the 1990s. This study describes the potential use of the technology in detecting disease.

Each breath exhaled by a person contains more than a thousand different molecules, some of which may be indicators of disease. For example, excess levels of methylamine may indicate liver or kidney disease, ammonia may be a sign of renal failure, elevated acetone levels may indicate diabetes, and nitric oxide levels can be used to diagnose asthma.

In this study, Ye and colleagues used the technique to analyze the breaths of several volunteers. They exhaled into an optical cavity (a space between two mirrors) and a pulsed laser light was then aimed into the optical cavity. The laser light bounced back and forth between the mirrors, covering a distance of several kilometers by the time it exited the optical cavity. During this time, the laser light struck all the molecules within the cavity.

The technology was able to detect a wide range of molecules, the scientists said. The findings, published in the current issue of Optics Express, suggest this technique, which still needs to be evaluated in clinical trials, may offer a low-cost, rapid and noninvasive method of health screening, the researchers said.

More information

The American Association for Clinical Chemistry has more about health screening tests.

SOURCE: Optical Society of America, news release, Feb. 18, 2008