BACKGROUND: Dietary restriction together with alteration of the gastrointestinal tract results in major metabolic changes and significant weight loss in patients undergoing bariatric surgery. Current methods of measuring these changes are often inaccurate and lack a molecular basis. The objective of this study was to determine the role of exhaled ketones as non-invasive markers of nutritional status in patients undergoing surgical treatment of obesity. METHODS: Patients at different stages of treatment for obesity were recruited to this single-centre cross-sectional study. The sample time points were as follows: (i) at the time of initial attendance prior to dietary or surgical interventions, (ii) on the day of surgery following a low carbohydrate diet, and (iii) > 3 months after either Roux-en-Y gastric bypass or sleeve gastrectomy. The concentrations of ketones within breath samples were analysed by selected ion flow tube mass spectrometry. RESULTS: Forty patients were recruited into each of the three study groups. Exhaled acetone concentrations increased significantly following pre-operative diet (1396 ppb) and bariatric surgery (1693 ppb) compared to the start of treatment (410 ppb, P < 0.0001). In comparison, concentrations of heptanone (6.5 vs. 4.1 vs. 1.4 ppb, P = 0.021) and octanone (3.0 vs. 1.4 vs. 0.7 ppb, P = 0.021) decreased significantly after dieting and surgical intervention. Exhaled acetone (ρ - 0.264, P = 0.005) and octanone (ρ 0.215, P = 0.022) concentrations were observed to correlate with excess body weight at the time of sampling. Acetone and octanone also correlated with neutrophil and triglyceride levels (P < 0.05). CONCLUSION: Findings confirm breath ketones, particularly acetone, to be a potentially clinically useful method of non-invasive nutritional assessment in obese patients.

Department of Surgery and Cancer Imperial College London St Marys Hospital London UK

J Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences Prague Czech Republic

Research Institute for Science and Technology in Medicine University of Keele Keele UK

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Mass Spectrom Rev. 2005 Sep-Oct;24(5):661-700 PubMed

Physiol Meas. 2011 Aug;32(8):N23-31 PubMed

Obes Surg. 2009 Apr;19(4):461-6 PubMed

Physiol Meas. 2006 Apr;27(4):321-37 PubMed

Ann Thorac Surg. 2004 Dec;78(6):2139-45; discussion 2145 PubMed

Obesity (Silver Spring). 2007 Dec;15(12):2875-88 PubMed

Metabolism. 2000 Nov;49(11):1453-9 PubMed

Obesity (Silver Spring). 2015 Dec;23(12):2327-34 PubMed

Analyst. 2011 Aug 21;136(16):3233-7 PubMed

Int J Oral Sci. 2011 Jul;3(3):160-4 PubMed

Obes Surg. 2006 Mar;16(3):251-7 PubMed

Eur Respir J. 2012 Sep;40(3):706-13 PubMed

J Chromatogr. 1983 Mar 11;273(1):67-75 PubMed

Toxicol Appl Pharmacol. 1984 Feb;72(2):201-9 PubMed

Rapid Commun Mass Spectrom. 2003;17(23):2655-60 PubMed

J Breath Res. 2013 Sep;7(3):036005 PubMed

J Breath Res. 2013 Mar;7(1):017118 PubMed

Obes Surg. 2016 May;26(5):1041-7 PubMed

Am J Clin Nutr. 1974 Nov;27(11):1212-3 PubMed

Lancet. 1959 Dec 26;2(7113):1157-9 PubMed

Free Radic Biol Med. 2015 Aug;85:157-64 PubMed

Clin Chem. 1993 Jan;39(1):87-92 PubMed

Cochrane Database Syst Rev. 2014 Aug 08;(8):CD003641 PubMed

Analyst. 2015 Apr 21;140(8):2573-91 PubMed

Quantification of volatile metabolites in exhaled breath by selected ion flow tube mass spectrometry, SIFT-MS