Especially in the UK liver disease has risen sharply over the past few decades and is the third biggest cause of premature mortality. Patients do not often present with symptoms until the disease is advanced. Even then diagnosis is difficult and the symptoms are often general and can be mistaken for other pathologies. Breath gas analysis is a non-invasive method to collect information on the state of an individual by monitoring the concentration of the volatile organic compounds (VOCs) present in the exhaled breath, which are directly correlated to their concentrations in blood.
Patients with a diseased liver showed very high levels of limonene, a flavour compound that is predominantly found in citrus fruits, in their breath—higher than in a healthy person, reports Raquel Fernandez del Rio, the lead author of the paper reporting these findings in EBioMedicine. Limonene, which is metabolised by a healthy liver, is accumulated in patients with liver disease. This hypothesis is supported by further studies on a sub-group of those patients before and after liver transplantation. Once the transplanted liver starts to work, limonene is cleared from the body.
Lukas Märk of Ionicon, whose proton transfer reaction mass spectrometer was used for the analysis, commented on the study: “A direct link between a compound’s concentration in breath and a disease state is a promising basis for the development of a clinical test. The non-invasive character of a breath test is captivating, especially in comparison to invasive alternatives such as a biopsy. But breath analysis has even more to offer: the possibility to analyse breath in real-time delivers immediate results, with a high-throughput and no waiting for lab tests. The analyser employed in this study, an Ionicon PTR-MS, has become the reference method for real-time breath analysis. Moreover, Ionicon provides an optimised inlet system for breath analysis with proton transfer reaction mass spectrometry (PTR-MS). Safety of patients has become an increasing focus, and even devices for non-invasive breath analysis have to comply with international regulations. The Ionicon BET-med system has been certified for clinical use, which allows real-time breath analysis of patients with Ionicon PTR-TOFMS instruments”.