title: Effect of hemodialysis and diet on the exhaled breath methanol concentration in patients with ESRD.
abstract: OBJECTIVE
  End-stage renal disease (ESRD) causes accumulation of nitrogenous waste products and acid-base, mineral, fluid, and electrolyte disorders, which are partially corrected by hemodialysis (HD). While the effects of ESRD and dialysis on body fluid composition are well known, the effects on composition of expired breath are uncertain. Methanol is produced from unabsorbable complex carbohydrates by the colonic microbiome. Dietary restrictions of fruits and vegetables aimed at limiting potassium intake lower the intake of dietary fibers; the reduced fiber intake can in turn reduce production of methanol and its appearance in the exhaled breath. In this study, we investigated the inter- and intradialytic changes in the breath methanol levels.
  
  
  METHODS
  Ten ESRD patients were studied during HD procedures at 3- and 2-day interdialytic intervals. On each occasion, 20 exhaled breath and room air samples were collected using evacuated canisters. Ten age-matched normal subjects served as controls. The samples were analyzed on a unique 6-column/detector gas chromatography system.
  
  
  RESULTS
  Seven ESRD patients consuming renal diet had lower methanol concentration (90 ± 29 ppbv) than the 3 patients consuming high-fiber diet (340 ± 48 ppbv, P ≤ .0006) and the 10 controls consuming unrestricted diets (202 ± 80 ppbv, P ≤ .001). HD significantly lowered breath methanol (60% ± 12%), paralleling the fall in serum urea concentration (70% ± 6%). The predialysis methanol concentration was slightly higher at 3-day than the 2-day interdialytic intervals.
  
  
  CONCLUSIONS
  Dietary restriction of fruits and vegetables lowers methanol production by the gut microbial flora in ESRD patients. Perhaps, methanol is a reliable breath biomarker to monitor individuals' daily fiber intake. Breath methanol is dramatically reduced by HD, reflecting its efficient removal.
authors.affiliation: Department of Chemistry, University of California, Irvine, California 92697, USA.
authors.forename: Hyun Ji Julie
authors.initials: HJ
authors.lastname: Lee
authors.forename: Madeleine V
authors.initials: MV
authors.lastname: Pahl
authors.forename: Nosratola D
authors.initials: ND
authors.lastname: Vaziri
authors.forename: Donald R
authors.initials: DR
authors.lastname: Blake
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D001806:Blood Urea Nitrogen; D001944:Breath Tests; D016022:Case-Control Studies; D004032:Diet; D045853:Exhalation; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000503:physiopathology*; D008297:Male; D000432:Methanol / Q000032:analysis*; D008875:Middle Aged; D006435:Renal Dialysis
chemical_list: D015415:Biomarkers; D000432:Methanol