title: Limonene in exhaled breath is elevated in hepatic encephalopathy.
abstract: Breath samples were taken from 31 patients with liver disease and 30 controls in a clinical setting and proton transfer reaction quadrupole mass spectrometry (PTR-Quad-MS) used to measure the concentration of volatile organic compounds (VOCs). All patients had cirrhosis of various etiologies, with some also suffering from hepatocellular cancer (HCC) and/or hepatic encephalopathy (HE). Breath limonene was higher in patients with No-HCC than with HCC, median (lower/upper quartile) 14.2 (7.2/60.1) versus 3.6 (2.0/13.7) and 1.5 (1.1/2.3) nmol mol-1in controls. This may reflect disease severity, as those with No-HCC had significantly higher UKELD (United Kingdom model for End stage Liver Disease) scores. Patients with HE were categorized as having HE symptoms presently, having a history but no current symptoms and having neither history nor current symptoms. Breath limonene in these groups was median (lower/upper quartile) 46.0 (14.0/103), 4.2 (2.6/6.4) and 7.2 (2.0/19.1) nmol mol-1, respectively. The higher concentration of limonene in those with current symptoms of HE than with a history but no current symptoms cannot be explained by disease severity as their UKELD scores were not significantly different. Longitudinal data from two patients admitted to hospital with HE show a large intra-subject variation in breath limonene, median (range) 18 (10-44) and 42 (32-58) nmol mol-1.
authors.affiliation: School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK. Author to whom any correspondence should be addressed.
authors.forename: M E
authors.initials: ME
authors.lastname: O'Hara
authors.forename: R
authors.initials: R
authors.lastname: Fernández Del Río
authors.forename: A
authors.initials: A
authors.lastname: Holt
authors.forename: P
authors.initials: P
authors.lastname: Pemberton
authors.forename: T
authors.initials: T
authors.lastname: Shah
authors.forename: T
authors.initials: T
authors.lastname: Whitehouse
authors.forename: C A
authors.initials: CA
authors.lastname: Mayhew
mesh_terms: D000328:Adult; D000368:Aged; D001944:Breath Tests / Q000379:methods*; D053138:Cyclohexenes / Q000378:metabolism*; D045853:Exhalation; D005260:Female; D006501:Hepatic Encephalopathy / Q000175:diagnosis*; D006801:Humans; D000077222:Limonene; D008297:Male; D008875:Middle Aged; D013729:Terpenes / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000032:analysis / Q000378:metabolism*
chemical_list: D053138:Cyclohexenes; D013729:Terpenes; D055549:Volatile Organic Compounds; D000077222:Limonene