Even in this age of high-tech tests, doctors can learn crucial information about a patient’s health just by smelling his/her breath. For example, breath that smells fruity may indicate the presence of acetone due to uncontrolled diabetes, while a fishy odor may be a red flag for kidney failure.
Latest development: Highly sensitive electronic sensors can now diagnose and monitor certain illnesses by testing for chemical compounds in the breath.
This breakthrough technology, which is still in its early stages of development, is based on the principle that biochemical changes in the body that are caused by illness produce a characteristic breath signature.
Breath analysis is already being used to diagnose and/or monitor common diseases, including stomach ulcers and asthma, and researchers are developing tests for such conditions as tuberculosis (TB) and lung cancer.
To learn more, Bottom Line/Health spoke with Cristina E. Davis, PhD, a professor at the University of California, Davis, and a leading specialist in chemical and biological sensing technologies…
Why is breath analysis considered an advance over the current tests that are used to diagnose diseases? One advantage is that breath analysis is completely noninvasive. You don’t have to tolerate a stick from a needle or even urinate into a cup. You simply breathe into a device. The accuracy of breath analysis is about the same as blood, urine and other types of medical tests.
Unlike tests that involve blood or other body fluids, breath testing can be performed and analyzed right in your doctor’s office instead of at a laboratory. You don’t have to wait for days (or weeks) to get lab results. Right now, you can get results from some tests in about 10 minutes. In the future, the information will most likely be available almost instantaneously.
I do not expect breath testing to replace other tests, but it will undoubtedly be combined with blood-work and other tests to gather more information.
How does breath analysis work? Every time you exhale, your breath carries thousands of different molecules. Many of these molecules are volatile organic compounds, substances that evaporate and potentially produce odors. These compounds can be detected with highly sensitive electronic sensors.
Some molecules in the breath are present only when you have a particular disease. With breath analysis, we can detect these molecules and also measure their concentrations. This information can be used both to diagnose a disease and to monitor some types of illness over time. Several tests are FDA-approved and sometimes covered by insurance.
Which breath tests can be used to diagnose medical conditions? Doctors are routinely using breath analysis to diagnose stomach ulcers and lactose intolerance.
Most stomach ulcers are caused by a bacterial infection. The organism, Helicobacter pylori (H. pylori), naturally breaks down urea, a chemical comprised of nitrogen and carbon, into carbon dioxide.
To diagnose this infection, the patient is given a capsule that contains urea with an isotope for detection. Then, the patient’s breath is tested for the presence of carbon dioxide—a positive result means that there is an H. pylori infection present, and antibiotic treatment is required. The test is repeated after treatment to make sure that the bacteria have been eradicated.
Lactose intolerance is diagnosed with a hydrogen breath test. Patients who have this condition can’t digest lactose, a sugar found in milk and other dairy foods, and experience gas, cramps and other digestive symptoms. To diagnose lactose intolerance, a patient consumes a lactose-containing solution. Then, the patient’s breath is tested every 15 minutes for two hours. High levels of hydrogen, produced by the fermentation of undigested lactose in the colon, could mean that the patient is lactose intolerant.
Are there any other breath tests now available? Yes. The Heartsbreath test is an important advance for patients who have received heart transplants. This test measures alkanes, substances that are elevated when there’s a risk for organ rejection in someone who has had a heart transplant.
Heartsbreath is used with a biopsy of the heart muscle to monitor signs of rejection. Signs of organ rejection are traditionally monitored by biopsy, imaging tests and blood tests.
How is breath analysis being used to monitor disease? Breath testing is now a key element in the treatment of asthma. Doctors can use levels of nitric oxide, a molecule that can be detected with a breath test, to determine whether medications and/or dosages need to be adjusted. Breath analysis, used with conventional asthma tests, such as spirometry and peak flow—both of which involve blowing into devices to measure airflow—gives a more complete picture of the lung inflammation that causes asthma symptoms.
Which breath tests are still in development? Tests to diagnose TB and lung cancer are being studied, and the results so far are quite promising. For example, the bacterium that causes TB produces a distinctive pattern of volatile organic compounds. One study found that breath testing can identify TB with about 80% accuracy. (The TB skin test, which takes 48 to 72 hours, often gives a false-negative result.)
Also, tests at the Cleveland Clinic have shown that breath analysis is about 81% accurate at detecting lung cancer. That’s comparable to the accuracy of a CT scan. The devices can also distinguish between different subtypes of lung cancer. Other tests are being developed for diabetes, kidney disease and colorectal cancer.
Breath analysis is one of the most exciting areas of medical research, with many new tests expected to be available in the next several years.