Exhaled Breath Provides Metabolic Fingerprint, May Be Helpful in Diagnosing Disease

Breath analyses may provide a "fingerprint" for individuals that can help diagnose certain diseases and other health problems.

According to a study in PLUS ONE, scientists suggest that there could be a better way for diagnosing certain health issues that would normally be detected through blood or urine, and as breath tests are non-invasive, the results are instantaneous and could prove even more convenient for various tests.

"I don't understand why breath hasn't been a widely used [means of] medical science diagnosis," said the study's lead author Renato Zenobi of the Swiss Federal Institute of Technology (ETH) in Zurich, according to the BBC.

"In traditional Chinese medicine, they feel your pulse, look at your tongue and smell your breath," he told BBC News. "There are trained dogs who can sniff cancer with a fairly good hit-rate - but the dog doesn't tell you what the compounds are."

Previous studies indicate that certain amounts of bacteria responsible for lung infections or even the presence of stomach cancer could be discerned in breath tests.

However, questions regarding whether each person's metabolic rate varied enough within an individual to act as a real and repeatable "breathprint" has yet to be determined.

"You need to show there is a core individual signal that is stable over time," Prof Zenobi said. "If it changes a lot during the course of the day or after you've had a coffee or smoked a cigarette, you can just forget about it."

Researchers used the breath samples of 11 volunteers across four time slots of nine working days. Samples were then run through a mass spectrometer-a device that measures all the masses of chemical compounds in breath.

Some, such as water vapour and carbon dioxide, were the same across all participants, but those that differed proved to be unique to individuals - and to stay the same for those individuals throughout the course of the experiments.

In the course of previous work, one of the collaborators' breath appeared to have one markedly different mass "peak" - which turned out to be connected to epilepsy medication he was taking.

When other patients on the same drug were tested, the same peak was found: a new metabolite of the drug that was subsequently published in the journal Chemical Communications.