Breath Analysis For Disease Detection

You may be breathing into a breathalyzer at your next checkup. The new "breathalyzer" technology is an advance in disease diagnosis. The technique is currently under development at the University of Wisconsin-Madison. It's a simple but very sensitive method used to distinguish normal and disease-state glucose metabolism. Breath testing is an exciting development in diagnostics because it is non-invasive and even more sensitive than the blood-based assays.

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The Science

Often, the process for disease detection is tedious, complicated, and many times leaves the patient and the doctor with ambiguous answers. Metabolomics is a new area of research that studies and characterizes the small molecules called metabolites found in an organism. Metabolomics allow scientists to look at genotype- phenotype and genotype-environment relationships by observing how a metabolome relates to the genotype of an organism, its physiology and its environment (what it eats or breaths). The relationship between a metabolome and its genotype or environment is critical information which can be used in many fields including pharmacology, drug trials and screenings. Here is a video with more information about this field.

Many diseases, including diabetes, cancer, and infections, alter the body's metabolism in a distinctive way. Metabolic changes can be detected by measuring the isotopic signature of carbon-containing metabolic byproducts in the blood or breath. The ratio of the isotopes in the blood or breath produces different patterns for a wide range of diseases. "Your body changes its fuel source. When we're healthy we use the food that we eat," senior author Fariba Assadi-Porter says. "When we get sick, the immune system takes over the body and starts tearing apart proteins to make antibodies and use them as an energy source." Scientists have advanced methods of tracing metabolic pathways that are disturbed from disease. When the body shifts from sugar to protein it engages different biochemical pathways and causes changes in the carbon isotope. The changes can be detected in exhaled carbon dioxide and analyzed for information on disease identification, development or recovery.

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The Study

The new study on metabolomics was published in the February 2012 issue of the journal Metabolism. Researchers from UWM studied mice with metabolic symptoms similar to those seen in women with polycystic ovary syndrome (PCOS). PCOS affects approximately 1 in 10 women by causing infertility, ovarian cysts, and metabolic dysfunction. Unfortunately the disease can only be diagnosed after puberty and only after ruling out many other diseases. The goal of this study was to use the change in isotope ratio due to metabolic changes to identify the earliest stages of a disease, which can be treated with diet and medication.

The mice were injected with glucose containing a single atom of the heavier isotope carbon-13. This isotope allowed scientists to trace which metabolic pathways were most active in sick or healthy mice. The change in ratio from carbon-12 to carbon-13 could be measured in minutes within the carbon dioxide exhaled by the mice.

Researchers were able to identify similar patterns using two independent assays. The study used nuclear magnetic resonance spectroscopy on blood serum and cavity ring-down spectroscopy on exhaled breath. These techniques were sensitive enough to detect a statistically significant difference between even small populations of healthy and sick mice. Currently, the cavity ring-down spectroscopy analysis uses a machine about the size of a shoebox, but a company called Isomark, LLC (co-founded by the researchers) is developing a hand-held "breathalyzer" that could be taken into rural or remote areas.

Take a Deep Breath

The new research shows that these biochemical changes can be detected much sooner than typical symptoms would appear- even within a few hours- offering hope of early disease detection and diagnosis. Another advantage of the breathalyzer is that it surveys the workings of the entire body with a single test and could provide almost immediate feedback on the effectiveness of treatments. "It's a cheaper, faster, and more sensitive method of diagnosis" says Porter.

There is currently a project underway called The Human Metabolome Project tasked with identifying and classifying every human metabolite, much like the classification of the human genome. Results have been promising and the more metabolites that are classified, the more scientists and doctors will be able to use the information to develop diagnostic tests for a wide range of diseases.

Resources

Metabolic "breathalyzer" reveals early signs of disease