title: Noninvasive measurement of plasma triglycerides and free fatty acids from exhaled breath.
abstract: BACKGROUND
  Although altered metabolism has long been known to affect human breath, generating clinically usable metabolic tests from exhaled compounds has proven challenging. If developed, a breath-based lipid test would greatly simplify management of diabetes and serious pathological conditions (e.g., obesity, familial hyperlipidemia, and coronary artery disease), in which systemic lipid levels are a critical risk factor for onset and development of future cardiovascular events.
  
  
  METHODS
  We, therefore, induced controlled fluctuations of plasma lipids (insulin-induced lipid suppression or intravenous infusion of Intralipid) during 4-h in vivo experiments on 23 healthy volunteers (12 males/11 females, 28.0 ± 0.3 years) to find correlations between exhaled volatile organic compounds and plasma lipids. In each subject, plasma triglycerides (TG) and free fatty acids (FFA) concentrations were both directly measured and calculated via individualized prediction equations based on the multiple linear regression analysis of a cluster of 4 gases. In the lipid infusion protocol, we also generated common prediction equations using a maximum of 10 gases.
  
  
  RESULTS
  This analysis yielded strong correlations between measured and predicted values during both lipid suppression (r = 0.97 for TG; r = 0.90 for FFA) and lipid infusion (r = 0.97 for TG; r = 0.94 for FFA) studies. In our most accurate common prediction model, measured and predicted TG and FFA values also displayed very strong statistical agreement (r = 0.86 and r = 0.81, respectively).
  
  
  CONCLUSIONS
  Our results demonstrate the feasibility of measuring plasma lipids through breath analysis. Optimization of this technology may ultimately lead to the development of portable breath analyzers for plasma lipids, replacing blood-based bioassays.
authors.affiliation: Department of Pharmacology, University of California, Irvine, Irvine, California 92697, USA. tminh@uci.edu
authors.forename: Timothy Do Chau
authors.initials: Tdo C
authors.lastname: Minh
authors.forename: Stacy R
authors.initials: SR
authors.lastname: Oliver
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Flores
authors.forename: Jerry
authors.initials: J
authors.lastname: Ngo
authors.forename: Simone
authors.initials: S
authors.lastname: Meinardi
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Carlson
authors.forename: Jason
authors.initials: J
authors.lastname: Midyett
authors.forename: F Sherwood
authors.initials: FS
authors.lastname: Rowland
authors.forename: Donald R
authors.initials: DR
authors.lastname: Blake
authors.forename: Pietro Renato
authors.initials: PR
authors.lastname: Galassetti
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods; D001944:Breath Tests; D002849:Chromatography, Gas / Q000379:methods; D045853:Exhalation / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000032:analysis* / Q000097:blood; D005240:Feasibility Studies; D005260:Female; D005544:Forecasting / Q000379:methods; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage; D008055:Lipids / Q000008:administration & dosage; D008297:Male; D009994:Osmolar Concentration; D014280:Triglycerides / Q000032:analysis* / Q000097:blood; D014894:Weights and Measures
chemical_list: D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids; D014280:Triglycerides